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Proposal Number: 10200053

Title: Summing Flares from EV Lac

PI Name: Claude Canizares

We propose to study the spectral and temporal behavior of flares from the active M-dwarf EV Lac. We will apply three powerful techniques: high-resolution spectroscopic diagnostics to infer flaring loop conditions (temperature, density, dynamics); measurement of flare scale heights from Fe K fluorescence; and state-of-the-art hydrodynamic flare models. The high rate of short flares, the X-ray signature of high density, and the evidence for opacity in X-ray resonance lines make EV Lac an ideal target. A deep flare exposure obtained by summing short events will provide one of the best high-resolution spectra possible for constraining physical models of M-dwarf coronae and flares with detail which can only be achieved through high resolution X-ray spectroscopy.

Proposal Number: 10200070

Title: Revealing the Origin of Hard X-rays in the Remarkable O4-O4 Binary Star System in M17: GTO component

PI Name: Gordon Garmire

The central massive stars in the closest Galactic Giant HII Region M17 are a pair of O4 stars separated by $1.8^{\prime\prime}$. A Chandra Large Project has revealed that both of these O4 stars are extraordinary X-ray sources, showing hard spectra and rapid variability typical of the luminous blue variable $\eta$ Carinae but almost unknown for normal O stars. Using He-like lines resolved by the HETG, we will diagnose whether this remarkable X-ray emission comes from magnetically-channeled wind shocks in single stars or from colliding-wind binaries; if the latter is the case, this pair of early O stars is really a system of four massive stars and constrains models of massive star formation. This is the GTO component of a combined GO/GTO observation (GO PI Marc Gagn\'e).

Proposal Number: 10200077

Title: G29.96-0.02: The enigma of ultra-compact HII regions

PI Name: Gordon Garmire

Young massive stars have strong stellar winds which sweep up and clear their environment. This is a key factor in stopping the star formation process and disrupting their nascent molecular clouds. We propose Chandra observations of the prototypical ultracompact HII (UCHII) region, G29.96-0.02. The proposed observations will provide direct evidence for this wind-cloud interaction. This target with its cometary morphology, low obscuration, and well-studied flow pattern in the surrounding gas, is optimal for X-ray study of the shocked wind plasma. Measuring the X-ray luminosity, spectrum and morphology of G29.96-0.02 will provide critical quantitative insights into the complex astrophysics of UCHIIs which cannot be acquired at long wavelengths.

Proposal Number: 10200079

Title: Search for triggered star formation in the type A bright rimmed cloud 34

PI Name: Gordon Garmire

Bright rimmed clouds (BRCs) near OB stars are excellent laboratories for the study of triggered star formation (TSF) due to the radiation driven implosion (RDI) mechanism. Type A BRCs are clouds at their earliest evolutionary stages and, according to the current theoretical modeling, are not expected to exhibit RDI TSF yet. Employing the Chandra's ability to effectively discern young stellar populations from unrelated old field objects we propose to observe the nearby Type A bright rimmed cloud BRC 34 and test predictions of RDI modelling. BRC 34 will also complement our large GO project on BRCs with the aim to study the RDI star formation efficiency in the Galaxy.

Proposal Number: 10200110

Title: Search for X-ray emission from magnetic chemically peculiar roAp stars

PI Name: Beate Stelzer

Whether intermediate-mass stars can generate X-ray emission is a long-standing problem. A shallow convective envelope is present, but in constrast to late-type dynamo-active stars their magnetic fields are geometrically simple and stable. Commonly any observed X-ray emission from intermediate-mass stars is ascribed to unresolved late-type companions. The rapidly osciallating Ap stars (roAp) are a class of cool, pulsating, chemically peculiar magnetic stars that are known to be single. Therefore, they are prime targets for the search for coronae in the presence of large-scale organized fields. For an explanation of the recent evidence of Promethium, all isotopes of which decay within two decades, flares seem to be the most plausible production mechanism.

Proposal Number: 10200113

Title: Imaging X-Ray Microjets from T Tauri Stars

PI Name: Manuel Guedel

Although many classical T Tauri stars (CTTS) drive bipolar jets, very little is known about the high-energy aspects of these outflows. Recently, two X-ray jets have been discovered from the microjet-driving T Tauri star DG Tau. Both jets are very soft X-ray sources and coincide with the optically visible, much cooler atomic jets. Although faint X-ray sources have also been identified for a few protostellar Herbig-Haro flows, CTTS offer the advantage of an unobscured view down to the star. A spectral anomaly reported for several microjet-driving CTTS (the presence of a strong, constant soft component) suggests that X-ray jets may be common in these objects. We aim at verifying this hypothesis. X-ray jets are potentially important for disk ionization, heating, and chemical processing.

Proposal Number: 10200170

Title: G333.6-0.2: An Embedded Giant HII Region in a Proto-OB Association

PI Name: Leisa Townsley

High-resolution X-ray observations of young massive stars and their surrounding clusters are yielding new insights into the star formation process. We wish to study many facets of massive star formation with a 60-ks ACIS-I observation of G333.6-0.2, a nearby Giant HII Region (GHR) formed very recently, along with two other very young GHRs, in the giant molecular cloud (GMC) G333. We will study embedded massive stars, their surrounding compact cluster of pre-main sequence stars, and the wider context of star formation and GMC evolution in G333, which may be an OB association in the making. We expect to identify hundreds of cluster members and perhaps diffuse X-rays tracing wind-shocked plasma filling G333.6-0.2's large-scale bipolar bubble.

Proposal Number: 10200216

Title: X-ray emission from the magnetic star alpha ^2 Canum Venaticorum ?

PI Name: J rgen Schmitt

We propose a 15 ksec pilot study with Chandra ACIS-S of the visual binary system alpha^2 CVn (= HR~4915 and HR~4914). With an angular separation of $\sim$ 21.3 arcsec this system can be easily resolved with {\it Chandra}. X-ray emission from alpha^2 CVn has been detected with the Einstein Observatory IPC and in the ROSAT RASS data, however, the angular resolution of these data is insufficient to attribute the detected X-ray emission to the F0 component HR~4914 or the A0spe component HR~4915. Since HR~4915 has a measured magnetic field of a few kG, the correct attribution of the detected X-ray emission has far reaching consequences. With the proposed 15 ksec ACIS-S pilot study at the binary HR~4914/4915 we can provide the feasibility of a possible grating observation.

Proposal Number: 10200260

Title: Activity and Rotation in the Zero Age Main Sequence cluster h Per

PI Name: Giuseppina Micela

We will explore the relation between the X-ray luminosity and rotational period in the young open cluster h Per. The age of this cluster (13 Myr) is crucial for the subsequent evolution of the stellar activity and rotation, being at the transition between the PMS and the ZAMS, when a star has reached its maximum rotational velocity. At that age both fast and slow rotators may co-exist, each group having dynamos and coronae following different regimes. h Per with its age and richness is an ideal target for these studies, hosting a very rich sample of coeval stars. We will also take advantage of the rotational periods recently derived with the program Monitor that is able to determine also relatively long rotational periods, allowing us to study at the same time slow and fast rotators.

Proposal Number: 10200267

Title: Berkeley 87: A Young Cluster Embedded in a Supersonic Wolf-Rayet Wind

PI Name: Stephen Skinner

The young open cluster Berkeley 87 in Cygnus (age 1 - 2 Myr; d = 950 kpc) is the only galactic cluster known to harbor a rare oxygen-type Wolf-Rayet star (WR 142). This WO-type star is in a highly-evolved pre-supernova state and its supersonic wind (v = 5500 km/s) is producing dissipative shock waves, as traced by diffuse optical CIV emission. Berk 87 shows clear signs of high-mass star formation including OH masers and compact HII regions. We propose to observe Berk 87 with ACIS-I. This observation will test theories of X-ray production in massive stars and determine if diffuse X-rays from the shocked WR wind are present.

Proposal Number: 10200270

Title: Unusual X-ray Emission from the Rapidly Accreting Young Star FU Orionis

PI Name: Stephen Skinner

FU Orionis objects are a class of very young low-mass stars that have undergone dramatic optical outbursts attributed to an increase in the disk accretion rate onto the star. The intense energy release from these outbursts will vaporize solid material in the terrestrial planet zone and may thus profoundly influence planet formation. We propose to observe the prototype of the class, FU Ori, with ACIS. It is rapidly accreting, has a powerful wind, and is known to have an unusual double absorption X-ray spectrum from a previous XMM observation. Chandra will provide the higher spatial resolution image and improved CCD spectrum needed to clarify the source morphology and origin of the unusual X-ray emission.

Proposal Number: 10200277

Title: ToO Studies with CXO of Pre-Main Sequence Stars Undergoing Optical Outbursts

PI Name: David Weintraub

Dramatic optical outbursts, which signal the onset of rapid and dramatic accretion onto pre-main sequence stars through their disks, cannot be predicted; however, our previous CXO campaign to study the outburst source V1647 Ori demonstrates that studies of such stars made with CXO beginning immediately after outburst can dramatically increase our knowledge about how and why such stars undergo outbursts and accrete mass. We therefore propose a ToO campaign to observe any such star discovered during Cycle 10. We will use ACIS-I to carry out three imaging spectroscopy observations of 20 ks, 20 ks, and 30 ks duration and spaced by intervals of three months, beginning immediately after discovery and continuing through the end of Cycle 10.

Proposal Number: 10200283

Title: IM Lup comes to age: A turnover from accretion to coronae?

PI Name: Hans Guenther

We propose to obtain a Chandra/HETGS spectrum of IM Lup with an exposure of 150 ks. IM Lup is the only known X-ray bright transition object between the classical T Tauri star phase and the weak-lined T Tauri phase. IM Lup shows an IR excess, but its Halpha equivalent width is small, indicating very low accretion rates. The Chandra spectrum will provide important information on the accretion process during the last stages of disk dispersal and therefore the latest possible time for planet growth. We will study the abundance pattern, trace the plasma density in He-like triplets, enhance the observational findings with accretion shock simulations and relate our results to the long-standing problem of disk dispersal and angular momentum evolution in young stars.

Proposal Number: 10200304

Title: The Cycles of Alpha Centauri

PI Name: Thomas Ayres

Alpha Centauri (G2V + K1V) is the nearest system of Sun-like stars; the primary long regarded a solar twin. The binary has been a popular target for previous X-ray missions, although the shrinking orbit now is resolvable only by Chandra. The 25 year X-ray record has revealed striking long term changes in the Alpha Cen coronae, including a deep X-ray minimum of the primary spotted by XMM in 2004-05. A recent LETGS pointing showed that the G star had become quite deficient in >2 MK emissions, but the softer 1 MK spectrum was little changed. Two additional 10 ks HRC-I snapshots in 2009 will continue this remarkable coronal narrative. We also propose key HST FUV spectra of the pair, to constrain emission measures and probe subcoronal dynamics.

Proposal Number: 10200353

Title: Using a Cool B Supergiant to Probe the Deepest X-Ray Emitting Layers of a Dense Stellar Wind

PI Name: Wayne Waldron

We are requesting a 234 ks HETGS observation of the early B supergiant Kappa Ori (B0.5Ia). Among the OB supergiants, Kappa Ori is one of the brightest, but it has not been observed at high spectral resolution. The wind properties of this star as compared to other OB stars will allow us to probe stellar wind distributed X-ray source models from a different perspective and allow us to address the serious issues pertaining to the origin of OB stellar X-ray emission. Models suggest that all f/i derived radii will be distributed at much deeper wind depths than previously determined allowing us to study the X-ray emission properties near the base of the wind. In addition, the first direct measurement of an OB stellar X-ray electron density may be possible.

Proposal Number: 10200414

Title: Collisionless plasma dynamics in WR140 near the 2009 eclipse and periastron

PI Name: Andrew Pollock

In January 2009, the two most extraordinary high-mass colliding-wind binary systems, eta Car and WR140, will both go through the periastron passages of their respective 5.5 and 7.9 year orbits. The preceding weeks are the most favorable for observing the rapid rise to X-ray maximum and learning fundamental lessons about shocks, hot plasmas and mass-loss in the upper HR diagram. Two HETGS spectra of WR140 before periastron and one after will capture its response to the changing physical conditions that follow the well-defined orbital geometry, offering unique information about the dynamics, dissipation and relaxation of collisionless shocks. The proposals on WR140 and eta Car will take advantage of opportunities for X-ray specroscopy that might nt arise again.

Proposal Number: 10200468

Title: Exploring the Stable Coronae of LP349-25 through X-ray and Radio Emission

PI Name: Rachel Osten

The observed correlation between X-ray and radio luminosities for active stars suggests a common coronal energy reservoir from which both processes (particle acceleration for radio emission and plasma heating for X-ray emission) draw. There is a discrepancy of four orders of magnitude in L_X/L_R for very low mass stars compared to active stars, but radio variability from a different emission mechanism may complicate the interpretation. We propose to obtain X-ray and radio observations of a radio-bright close binary, LP349-25, to explore the L_X/L_R relationship for this object with apparently constant radio emission.

Proposal Number: 10200496

Title: Anomalous Adara: The Spatial and Spectral Properties of Extended X-Ray Emission

PI Name: david huenemoerder

We propose to obtain a 10ks ACIS image and spectrum of Adara (epsilon CMa) to characterize an unusual and unexplained spatially extended emission feature in this astrophysically important object. This supposedly non-variable B2 II star shows extended emission in the LETGS zero order and in the spatial dimension of the dispersed spectrum. The LETGS spectrum shows an unusual and broad (10 A) excess centered on 30 A (0.4 keV). The spectral excess was not present in XMM/RGS spectra taken 5 years earlier. Since Adara is noted for its absence of variability, its very low line-of-sight column density, and high EUV flux, it is considered to be a standard for B2 supergiant atmospheric and wind studies. Something has changed. ACIS data are necessary to understand this unprecedented feature.

Proposal Number: 10200509

Title: Testing the Colliding Wind Paradigm: X-rays from the Wolf-Rayet Binary System WR 147

PI Name: Svetozar Zhekov

We propose a deep HETG exposure of the Wolf-Rayet binary system WR 147. The excellent gratings and zero-order data will be used to put tight constraints on the validity of the colliding stellar wind (CSW) mechanism assumed responsible for the X-rays from this object. The detection of broad emission lines with profiles and centroids in agreement with synthetic colliding wind spectra, along with confirmation of the spatially extended X-ray emission reported from the previous short HRC-I exposure, would support the colliding wind picture. On the other hand, narrow (or unresolved) unshifted emission lines would require an interpretation other than CSW. Thus, this study will be the most rigorous test of the CSW paradigm in a WN+OB binary so far.

Proposal Number: 10200574

Title: V2129 Oph: a close look at a CTTS

PI Name: Ettore Flaccomio

We propose to obtain a high resolution X-ray spectrum of the CTT star V2129 Oph in the \rho Ophiuchi star forming cloud. The 200 ks Chandra observation is part of a larger program that includes optical Doppler and Zeeman-Doppler mapping of the stellar photosphere and magnetic field and a simultaneous monitoring of accretion signatures. V2129 Oph is one of the two CTTS for which a magnetogram has been published. Our primary objective is to derive the differential emission measure and the density of the cool plasma at the accretion shock, directly testing the prediction of a published coronal and accretion model, revised with new maps of the magnetic field.

Proposal Number: 10200596

Title: X-RAY AND FUV PHOTO-IONIZATION/-EXCITATION OF TRANSITIONAL DISKS AROUND THE PMS STARS HD135344B and Lk Halpha 330

PI Name: Alexander Brown

Transitional disks have transformed most of the dust and gas in their inner regions into planetesimals or larger solid bodies. They are a rare, short-lived phase of PMS disk evolution and provide important physical insights and modeling constraints on disk and protoplanetary system evolution. We propose to observe two intermediate mass stars with transitional disks, HD135344B and Lk Halpha 330, using ACIS-S on Chandra and the COS FUV spectrograph on HST. We will use these spectra to determine the coronal, transition region, and upper chromospheric emission measure distribution, covering temperatures from 10,000 K to 10 MK, and then calculate the full X-ray/EUV/FUV radiation field for use in modeling its photoexcitation/photoionization effects on the disk structure.

Proposal Number: 10200618

Title: Testing Shock Dynamics in Eta Carinae with HETGS After the 2009 Periastron Passage

PI Name: Michael Corcoran

We propose 2 HETGS observation after the X-ray minimum/periastron passage of Eta Car in Jan. 2009. These observations will take place just after the end of the "high absorption" interval, and just before the wind-blown "bubble" around the companion star breaks through the wind of Eta Car. The X-ray line profiles will be used with previously awarded HETGS observations before the minimum and synthetic line profile models and 3-D wind models and compared to the variations during the 2003.5 minimum to constrain fundamental properties of the flow like the size of the emitting region.

Proposal Number: 10200738

Title: Evolution of Young Stars in the Large Massive Cluster Cep OB3b

PI Name: Thomas Allen

We propose deep ASIC-I imaging of the CepOB3b cluster, a large (> 1000 member), 5 Myr old cluster, 700 pc from the Sun. Spitzer observations have mapped the full extent of CepOB3b, showing two distinct sub-clusters. We will target each sub-clusters to identify the young stars without disks and determine the X-ray properties of the stars. These observations will probe the properties of a young cluster and its constituent stars at a poorly studied evolutionary age, thereby complementing the COUP survey of the 2 Myr old Orion Nebula Cluster. We will study the dynamical evolution of clusters emerging from their parental clouds, the evolution of stellar coronae, the affect of circumstellar disks on the X-ray emission, and the role of X-rays in creating inner holes in disks.

Proposal Number: 10200757

Title: The true nature of HD 110432: the most extreme gamma Cas analog

PI Name: Jose Torrejon

We propose to use the high resolution capabilities of Chandra gratings to study the nature of the Be/X-ray source 1H1249-637=HD 110432, the most extreme of the known gamma Cas analogs. Two hypotheses have been put forward to explain the origin of the X-ray emission in these objects: a) accretion onto a compact object and b) emission from the star+disk interaction through stellar magnetic fields. Both of these challenge profoundly our current understanding of the structure of massive stars and/or how binary systems evolve. HD110432 displays extreme conditions within its class: the hottest plasma (> 20 keV), the hardest spectrum, an enormous circumstellar disk and a close to edge-on inclination.

Proposal Number: 10200787

Title: The Origin of Hard X-rays in M17's Remarkable O4-O4 Binary

PI Name: Marc Gagne

At 2 kpc M17 is the nearest giant HII region, with 10,000 stars younger than 1 Myr and a prominent X-ray champagne flow. At the heart of M17 are CEN 1A and 1B, a visual pair of O4 stars separated by only 1.8". A long series of ACIS observations show that each O4 star is a very hard time variable X-ray source. We suggest that one or both O4 stars are themselves colliding wind shock binaries or, alternatively, that one or both have strong magnetic fields. We propose to obtain time-resolved, spatially resolved HEG/MEG spectra of both stars to measure He-like line ratios and line profiles to directly test these two models. This roll-constrained 150-ks GO proposal is tied to a 25-ks GTO proposal (PI: Garmire) for the same target.

Proposal Number: 10200804

Title: Constraining the Effects of High Energy Photons on Proto-Planetary Disk Chemistry and Evolution

PI Name: Gregory Herczeg

We propose to conduct a multi-wavelength monitoring campaign of two classical T Tauri stars (TW Hya and GM Aur) that possess transitional disks, produce variable [Ne II] emission, generate substantial X-ray emission, and are still actively accreting. Leveraging the variable nature of X-rays, [Ne II] emission, and the mass accretion rates of these sources, we will search for a correlations in these data to provide the first direct observational evidence of the role X-rays and EUV photons play in driving disk chemistry and the evolution of proto-planetary disks. We request three independent observations of each source over the next year supported by ground-based observations with the mid-IR spectrograph MICHELLE on Gemini North and the R-C optical spectrograph on SMARTS at CTIO.

Proposal Number: 10200840

Title: CORONAL AND TRANSITION REGION HEATING DUE TO MAGNETIC ACTIVITY ON METAL-POOR DWARF STARS

PI Name: Alexander Brown

How does low metallicity affect the heating and resultant temperature structure of the chromospheres/transition regions/coronae of old solar-like dwarf stars? Our ACIS-S observations of 7 Gyr old Arcturus Moving Group (AMG) dwarfs show very little conventional coronal (> 1 MK) plasma and suggest that these stars have insufficient magnetic energy input to power a solar-like corona. However, they do have chomospheres and transition regions similar to the minimum activity Quiet Sun. It this typical or an aberration of the AMG? We propose a 35 ksec ACIS-S observation of the nearest (9.2 pc), truely metal-poor ([Fe/H] = -1.4) dwarf star that is known to have definite magnetic dynamo activity (activity cycles, active region modulation) -- HD103095 -- to investigate this question further.

Proposal Number: 10200900

Title: Direct X-ray measurements of the expansion of planetary nebulae

PI Name: Young YU

We propose the first direct measurements of the proper motion of X-ray-emitting regions within planetary nebulae (PNs), via new Chandra observations of the PNs NGC 7027 and BD +303639. In the case of NGC 7027, measurement of the speeds of X-ray-emitting jets will provide a straightforward and unique test of simple jet shock models and unparalleled insight into the evident rapid structural evolution of this seminal young PN. In the case of BD+303639, confirmation of our tentative result that its X-ray ``hot bubble'' is expanding at about 200 km/s would represent a milestone in our understanding of the wind interactions that shape PNs.

Proposal Number: 10200901

Title: X-ray Monitoring of Eta Car in 2009: Unveiling the Deep X-ray Minimum

PI Name: Kenji Hamaguchi

X-ray observations of Eta Car near the 2003 periastron passage confirmed that the X-ray emission primarily arises from wind-wind collision (WWC) in a binary system, but raised fundamental questions about the cause of the 3 month-long minimum. The current promising mechanism is either an eclipse of the WWC plasma by primary winds or a fading of the WWC activity due to an increase in gas density, which relates to the mass loss mechanism which influences the evolution of massive stars. To test these scenarios, we propose key, targeted high signal-to noise observations of the faintest phase missed in 2003 to track both the flux and spectral variations. We request joint observations of Eta Car with Chandra and XMM-Newton around the 2009 minimum.

Proposal Number: 10200921

Title: AO-10 Calibration Observations to Monitor the Spatial Variations in the HRC-I Gain

PI Name: CXC Calibration

We continue to monitor the small scale gain variations in the HRC-I with raster scans of ArLac.

Proposal Number: 10200922

Title: AO-10 Calibration Observations of Capella

PI Name: CXC Calibration

We continue to monitor the dispersion relation of the gratings with annual observations of Capella.

Proposal Number: 10200923

Title: AO-10 Calibration Observations to Monitor the Spatial Variations in the HRC-S Gain

PI Name: CXC Calibration

We continue to monitor the small scale gain variations in the HRC-S with raster scans of ArLac.

Proposal Number: 10200926

Title: AO-10 Calibration Observations of HZ43

PI Name: CXC Calibration

We continue to monitor the low energy response of the HRC with observations of HZ43.

Proposal Number: 10200930

Title: AO-10 Measurements of the optical/UV Transmission of the HRC Filters.

PI Name: CXC Calibration

We continue to monitor the optical/UV transmission of the HRC filters with observations of Vega.

Proposal Number: 10300001

Title: Resolving short supersoft source states of optical novae in the core of M31

PI Name: Wolfgang Pietsch

We propose to continue the monitoring of the M31 core with 5x23ks XMM EPIC and 5x20ks Chandra HRC-I observations equally distributed from Nov 2008 to mid Feb 2009 to determine additional lightcurves for short SSS states of optical novae. SSS states with <100 d duration indicate accreting massive white dwarfs. They are proposed as SN Ia progenitors and determining their frequency is very important. We will correlate detected sources with novae from optical monitoring. With a nova rate in the field of ~25/yr and SSS states lasting from weeks to years we will follow light curves of many novae. Durations of the nova SSS state will allow us to constrain envelope and whitedwarf masses. We will also monitor time variability of ~200 M31 centre X-ray sources (mostly XRBs).

Proposal Number: 10300026

Title: Resolving short supersoft source states of optical novae in the core of M31

PI Name: Peter Predehl

We propose to continue our monitoring of the M31 core by 2x20ks Chandra HRC I observations mid and end Feb 2009 to determine the light curves of the short SSS states of optical novae. SSS states with $<$100 d duration indicate accreting massive white dwarfs (WD). They are proposed as SN Ia progenitors and determining their frequency is very important. The detected sources will be correlated with optical nova positions from monitoring programs covering the same area. With a nova rate in the field of ~25/yr and SSS states lasting from weeks to years we will simultaneously follow light curves of many novae. The durations of the nova SSS state will allow us to constrain the envelope and WD masses. We will also monitor time variability of ~200 M31 centre X-ray sources (mostly XRBs).

Proposal Number: 10300323

Title: Chandra Observation of a New Galactic Globular Cluster -- FSR 584

PI Name: David Pooley

We propose a 20 ksec ACIS-S3 observation of the star cluster FSR 584, which was recently discovered in 2MASS data and argued to be a globular cluster. This heavily obscured object lies nearly in the Galactic plane at only 1.4 kpc, making it the closest globular cluster. A relatively short observation will allow us to take a census of the X-ray emitting objects in this cluster (with Lx > 4x10^30 ergs/sec), such as quiescent low-mass X-ray binaries, cataclysmic variables, millisecond radio pulsars, and chromospherically active main-sequence binaries. As our work with another recently discovered globular cluster in the plane (GLIMPSE-C01) has shown, Chandra data can be used to help rule out the alternative for this object, namely, an old open cluster.

Proposal Number: 10300356

Title: CP Puppis, a template for the secular evolution of novae

PI Name: Marina Orio

We propose a Chandra HETG observation of the extraordinary quiescent nova CP Puppis, to follow up on our XMM-Newton study. The HETG spectrum will provide a tighter constraint on the cooling flow model fit, which we have used to infer the white dwarf mass and the mass accretion rate in this nova, testing the theory of nova outbursts. Chandra will allow us to spatially resolve the nova shell, and to understand whether the O VII triplet originates in the shell or whether photoionization is important. We will perform sensitive diagnostics using a wide range of lines. CP Puppis offers a unique possibility to prove the dependence of the thermonuclear burning evolution on the physical parameters of the system.

Proposal Number: 10300452

Title: RS Ophiuchi: First X-ray Jet from a Nova

PI Name: Jennifer Sokoloski

A highly collimated outflow from a nova has been imaged for the first time, both in the radio, and in the X-rays with Chandra. With its high velocity and its synchrotron radio lobes, this outflow from the symbiotic star RS Ophiuchi pushes the exploration of non-relativistic jets into a new regime. The production of a collimated jet within a few days of outburst also challenges the assumption that in a nova the blastwave sweeps away the accretion disk. We propose a second Chandra image of the evolving jet from RS Ophiuchi to determine the properties of this new type of jet, the conditions that led to its production, and the nature of the accretion disk that must have survived the nova explosion. This work has implications for our fundamental understanding of both jets and novae.

Proposal Number: 10300531

Title: Grating spectroscopy of a bright nova in outburst

PI Name: Thomas Nelson

We propose a TOO program to obtain LETG spectroscopy of a classical or recurrent nova in outburst, if it is observed to turn into a luminous supersoft X-ray source with Swift. In the rare case that a nova has unusually luminous hard X-ray flux in the initial stages, we also propose to obtain a HETG spectrum of the ejected shell. Our aims are: a) to constrain the mass, temperature and chemical composition of the white dwarf by analyzing the spectrum, b) to correlate spectral and temporal variablility during the nuclear burning phase, and c) to use the HETG to explore wind mass loss in a recurrent nova. The proposed study is important not only for nova/CV theory, but for understanding supernova Ia progenitors.

Proposal Number: 10300566

Title: The Nature of the Soft Component in the Symbiotic Star CH Cygni

PI Name: Koji Mukai

The symbiotic star CH Cyg consists of an M giant and a white dwarf, and displays a two-component X-ray spectrum. The absorbed hard X-ray component is likely due to accretion onto the white dwarf. The unabsorbed soft X-ray component is thought to be either due to colliding winds or due to photoionization of the M giant wind by the hard component. We propose to obtain a high signal-to-noise grating spectrum of CH Cyg to resolve the origin of its soft component. Once we know its origin, we can begin to probe the environment around the white dwarf using the detailed spectral shape of the soft component. We propose this as a slow TOO, to be triggered when we know that CH Cyg is X-ray bright.

Proposal Number: 10300586

Title: PlaN-B: The hyperactive coronae of interacting companions in planetary nebulae

PI Name: Orsola De Marco

With this proposal we seek to obtain ACIS-S spectra of two central stars of planetary nebula, known to have post-common envelope central stars with main sequence companions. We expect these companions to have been spun up during the common envelope and to have X-ray bright cornoae as a result. These detections will establish the X-rays as a way of detecting M-type main sequence companions to central stars, which are hard to detect with other methods. The Lx and Tx will be compared to prediction from models and will be used to carry out a first determination of the amount of mass and angular momentum accreted during the common envelope.

Proposal Number: 10300600

Title: Uncovering the interacting binary population in NGC 6681

PI Name: Andrea Dieball

We propose to carry out 70 ksec X-ray imaging of the globular cluster NGC 6681 with Chandra. This cluster was extensively observed in the FUV with HST, yielding the deepest FUV survey of a globular cluster to date. Our X-ray observations will allow us to (i) find X-ray counterparts to the white dwarf - main sequence star binaries in our ultra-deep FUV survey, thus identifying and confirming the cataclysmic variables amongst them; (ii) detect the X-ray faintest interacting binaries (IBs) in this cluster; (iii) classify all X-ray sources based on their X-ray, FUV and optical properties; (iv) and finally, using all the information obtained, test models for IB formation and evolution and verify the empirical results emerging from previous work on other clusters.

Proposal Number: 10300704

Title: Understanding the Current Dynamical States of Globular Clusters

PI Name: David Pooley

We appear to be on the verge of a major paradigm shift in our understanding of the current dynamical states of Galactic globular clusters. Fregeau (2008) brought together two recent theoretical breakthroughs as well as an observational breakthrough made possible by Chandra -- that a globular cluster's X-ray source population scales with its dynamical encounter frequency -- to persuasively argue that we have misunderstood the dynamical states of Galactic globular clusters. The observational evidence hinges on Chandra results from clusters which are classified as "core collapsed," of which there are only a handful of observations. I propose a nearly complete census with Chandra of the rest of the "core collapsed" globular clusters.

Proposal Number: 10300769

Title: Searching for Millisecond Pulsars in Extremely Low-Mass White Dwarf Binaries

PI Name: Craig Heinke

Several extremely low-mass white dwarfs, with masses below 0.24 solar masses, have recently been discovered in large surveys. These white dwarfs cannot be formed through the evolution of single stars, and several are known as companions of millisecond radio pulsars. We propose a search for X-ray emission from six relatively bright extremely low-mass white dwarfs to distinguish between neutron star vs. white dwarf companions. New millisecond pulsars with companions amenable to spectroscopy are of great interest, while ruling out neutron star companions will put constraints on common envelope models for double white dwarf evolution.

Proposal Number: 10400006

Title: Weighing the ULX in M82 via QPO-Spectral Correlations from Simultaneous Chandra and XMM-Newton Observations

PI Name: Hua Feng

The ultraluminous X-ray source (ULX) X41.4+60 in M82 is one of the best intermediate-mass black hole candidates. It shows luminosities 500 times the Eddington limit of a neutron star and quasi-periodic oscillations (QPOs) at frequencies lower than typical in stellar-mass black holes. It is the only ULX from which QPOs have been detected that is in a hard state and, thus, provides a unique opportunity to determine if the QPO frequency is correlated with spectral state as in stellar-mass black holes. We propose simultaneous Chandra and XMM observations to determine the relation between QPO frequency and spectral properties for X41.4+60. This may lead to constraints on the compact object mass.

Proposal Number: 10400008

Title: INVESTIGATING NEW INTEGRAL SOURCES WITH CHANDRA

PI Name: Adamantia Paizis

We propose to trigger a maximum of 2 Chandra medium (4-12 days) ToO observations on new sources discovered by the INTEGRAL Observatory. We ask for 20 ksec per observation, using HETGS. The scientific aim is to determine the source position with sub-arcsecond accuracy that only Chandra can provide, enabling multi-wavelength follow-up observations (also coordinated within the proposing team), and to obtain the high resolution HETGS X-Ray spectrum, essential to determine the nature of the new source. With this proposal we aim to continue the successful INTEGRAL-Chandra monitoring program started since Chandra AO5.

Proposal Number: 10400009

Title: High Resolution Spectroscopy of a Black Hole Transient

PI Name: Jon Miller

We propose to continue our ongoing study of Galactic black hole transients in outburst in a streamlined form, via two (2) 30 ksec HETGS observations. This program has revealed relativistic Fe K disk lines, warm-absorber-like disk winds, and now a possible anti-correlation between winds and jets. Observations of a new transient outburst will permit a black hole spin constraint, and test connections between disks, winds, and jets as a function of accretion rate. We will support this program with a global multi-wavelength network of observatories.

Proposal Number: 10400046

Title: Chandra follow-up of weak persistent sources found in INTEGRAL maps

PI Name: Jelle Kaastra

We propose to obtain a 1 ksec exposure of up to 2 newly found unclassified INTEGRAL sources which are weak persistent X-ray sources (we exclude from this proposal the bright new transients discovered by INTEGRAL). The unique Chandra positional capabilities will allow for an optical follow-up study. Follow-up observations are of paramount importance for the classification of the sources (e.g. as HMXBs/LMXBs, pulsars (and pulsar wind nebula) or in a few rare cases as AXP/SGR or INS).

Proposal Number: 10400048

Title: Chandra follow-up of weak persistent sources

PI Name: Jelle Kaastra

We propose to obtain short exposures of a sample of unclassified sources which are likely weak persistent X-ray binaries. The unique Chandra positional capabilities will allow for an optical follow-up study. Follow-up observations are of paramount importance for the classification of the sources (e.g. as HMXBs/LMXBs, pulsars or in a few rare cases as AXP or DIM). The ACIS sensitivity for hard sources is best while pile-up is no major concern for source localization.

Proposal Number: 10400049

Title: Chandra LETG observation of an ultra-compact X-ray binary candidate

PI Name: Jelle Kaastra

We propose to obtain a long exposure of the Ultra-compact X-ray binary in Terzan 2.

Proposal Number: 10400067

Title: Observe Z sources at High Mass Accretion Rates

PI Name: Claude Canizares

We propose to test a new interpretation that links mass accretion rate to observed spectral changes in Z-sources in a diffwrent way than previously though. Integral part of the test is to catch Z-source on the horizontal branch (HB). There are a few sources where RXTE and previous observatories established a fairly accurate record of how often they appear on a specific spectral branch. 4 observations for 8 ks each has a 50% chance to observe GX 5-1 on the HB.

Proposal Number: 10400071

Title: Chandra Observations of the Low Mass X-ray Binary 4U 1556-60

PI Name: Claude Canizares

4U 1556-60 is a LMXB in a 9.1 hour orbit, that has been identified (based upon its X-ray colors) as an atoll source, although no bursts have been identified to secure its classification as a neutron star. Spectrally, models that consist of an accretion disk plus a Compton corona, or models that consist of a black body (e.g., neutron star surface emission) plus a hard, but very exponentially cutoff tail, both seem to fit BeppoSAX data equally well. Here we propose to view this system, for nearly one full binary orbit, with the Chandra HETG. We hope to better gauge whether the bulk of the soft emission is coming from a neutron star surface, or the atmosphere of a Comptonized accretion disk.

Proposal Number: 10400163

Title: X-Ray Jets in Microquasars

PI Name: Stephane Corbel

We propose Target of Opportunity (ToO) observations for detailed studies of X-ray jets from microquasars. We describe our discovery of radio/X-ray jets in two microquasars, why X-ray jets are probably much more common than previously thought, and transient X-ray jets offer an exciting new way to probe the physics of relativistic jets from black holes. The proposed ToO observations are optimized to discover and study (flux evolution, morphology, SED, proper motion, ...) of new X-ray jets from microquasars, triggered by their detection as radio lobes. This will have implications not only for the study of jets from Galactic X-ray binaries, but also for our understanding of relativistic jets from active galactic nuclei (AGN).

Proposal Number: 10400165

Title: Transient LMXBs in Globular Clusters: More Numerous Than We Thought?

PI Name: David Pooley

Since the discovery of globular cluster LMXBs in the 1970s, it was assumed that there was only one bright LMXB per cluster. Deep Chandra observations of several globular clusters have revealed that they contain numerous quiescent LMXB systems, any of which could go into outburst. Our observations will determine whether new outbursts from transient LMXBs in NGC 6440, Terzan 5, and Terzan 1 are from the same sources that were previously seen in outburst.

Proposal Number: 10400218

Title: ToO observations of the microquasar GRS 1915+105 in quiescence

PI Name: Paolo Soleri

We propose two Chandra observations (40 ks each) to detect the microquasar GRS 1915+105 in quiescence, should its current 16-year-long outburst end during the 10th Chandra observing cycle. This system has never been observed in quiescence: its properties suggest that its quiescent X-ray flux would be rather high (~ 10^34 erg/s), allowing a measurement of the spectrum and a test of models for quiescent emission in black-hole binaries. In addition, it will be possible to detect a fossil jet similar to that detected in the black hole candidate 4U 1755-33.

Proposal Number: 10400234

Title: Precise Localization of Neutron Star Soft X-Ray Transients

PI Name: Deepto Chakrabarty

We propose to observe four neutron star soft X-ray transients (NS SXTs) in outburst to obtain accurate source positions, continuing a successful multi-cycle program in place since Cycle 6. These positions will allow reobservation of this sources in the X-ray, optical, and infrared bands in order to study their quiescent emission. This program will increase the number of known SXTs with good positions, providing a more uniform sample for future work. We will only trigger our program for sources in crowded or obscured fields where a position from another instrument (e.g., Swift) is not sufficiently constraining.

Proposal Number: 10400238

Title: ToO observation of a bright Galactic transient discovered by GLAST and Swift

PI Name: Isabelle Grenier

We propose a TOO observation of one bright Galactic transient detected by the GLAST large area telescope, and followed by a Swift-XRT detection. Our goal is to determine the nature of an event similar to the intense, non-blazar, transient that EGRET has detected near the Galactic plane once in its lifetime. The lack of a radio-loud blazar counterpart and of a spacially coincident X-ray binary indicates either a new manifestation of a non-blazar active galaxy lying behind the Milky Way, capable of producing massive gamma-ray flares, or a new facet of Galactic compact objects. A significant XRT detection of an X-ray counterpart will trigger the proposed 30 ks Chandra observation to locate precisely this counterpart, to constrain the X-ray decay time, and to measure the source spectrum.

Proposal Number: 10400252

Title: Chandra observations of newly discovered, nearby, globular clusters in the Galaxy

PI Name: EDWARD CACKETT

We propose short, 10 ksec Chandra observations of two recently discovered nearby (~1.5 kpc) globular clusters FSR 1767 and FSR 584. We will determine their X-ray source population and confirm their globular cluster nature. As they are the two closest globular clusters to the Sun, their proximity gives us an unprecedented look. If we discover any quiescent low-mass X-ray binaries, they will be some of the very closest known to us, enabling a study of their properties in unrivaled detail, especially because of the known distance and reddening.

Proposal Number: 10400273

Title: Understanding the nature of high inclination low mass X-ray binaries: broad-band and line spectra from A1744-361

PI Name: Tod Strohmayer

We propose to observe the transient, dipping neutron star low mass X-ray binary (LMXB) system A1744-361 during an outburst with the CHANDRA HETGS, and contemporaneously with RXTE. This will be the first observation of A1744-361 with a high resolution spectral instrument. With these observations we will: 1) search for narrow absorption lines for the first time from A1744-361; 2) measure the profile of its broad iron emission line; 3) unambiguously determine the binary orbital period and source position; 4) search for kHz QPOs and burst oscillations. These studies will allow us to further understand the ionized plasma in the immediate environs of A1744-361, and dippers in general. These goals rely on the unique capabilities of CHANDRA (high spectral and angular resolution) and RXTE.

Proposal Number: 10400329

Title: Crustal cooling in the neutron star KS 1731-260

PI Name: EDWARD CACKETT

We propose a 60 ksec observation of the quasi-persistent neutron-star low-mass X-ray transient KS~1731-260 in quiescence. The long outbursts of this source heated the neutron star crust out of thermal equilibrium with the core. We have tracked the cooling of the neutron star crust in this object since it went into quiescence. Empirical fits to the data are not yet conclusive as to whether cooling has ceased or may continue. Furthermore, recent theoretical work motivated by our observations predict that the cooling may continue if the neutrino emissivity in the core is high. Our proposed observation will determine whether cooling has continued further constraining models for the neutron star crust and core, and will test whether residual accretion is important.

Proposal Number: 10400350

Title: X-ray Column Density Towards The Low Mass X-ray Binary 4U 1608-522

PI Name: Feryal Ozel

We request a 25~ks observation of the low-mass X-ray binary 4U 1608-522 with Chandra HETG in order to measure the interstellar extinction towards the source using absorption edges in its spectrum. The measurement of the column density is critical for two reasons. First, we will employ the independent grating measurement when fitting continuum X-ray spectra of the source to determine the temperature of the neutron star surface. Second, we will employ the extinction measurement to determine the distance to the source using a technique that makes use of red clump stars in the field of view of the source, which we have already extracted from the 2MASS archival data. The ultimate goal is to determine the mass and radius of the neutron star in this binary to a high accuracy.

Proposal Number: 10400384

Title: Following a black hole candidate X-ray transient to quiescence

PI Name: Peter Jonker

There is increasing evidence that the quiescent state of BH X-ray binaries is different from the canonical hard state. Our recent Chandra campaigns on BH transient decays suggest that the spectral hardening in the hard state decay stops. This transition has so far not been resolved with enough SN to fully quantify it, but there are strong indications that the spectrum softens during the subsequent decay. We also find evidence that the decay rate varies between sources. Both the decay and spectral evolution can provide important constraints for jet-dominated and ADAF models. We now request 4 instead of 6 simultaneous Chandra/VLA TOO observations. The early part of the decay can be covered with approved Swift ToO and existing radio proposals.

Proposal Number: 10400393

Title: Looking at the quiescence of the unique system GRB 070610/Swift J195509.6+261406

PI Name: Nanda Rea

We propose for a 68ks ACIS-S observation aimed at determining the nature of the unique system GRB 070610/Swift J195509.6+261406. This very peculiar system, discovered as a long gamma-ray burst (GRB 070610), is most likely a low mass X-ray binary (LMXB) hosting either a neutron star (NS) or a black hole (BH). This is the only LMXB associated with a typical long-duration GRB. The discovery of this source challenges the current picture of long GRBs being all due to cosmological objects. Very deep X-ray observations of this system in its quiescent state are needed in order to disentangle the nature of the system, in particular of its compact object, and then study the expected rate of GRBs with LMXB origin.

Proposal Number: 10400405

Title: Crust cooling of bright neutron star transients with long recurrence times

PI Name: Nathalie Degenaar

We propose a series of three Chandra ToO observations of a bright neutron star X-ray transient with a long recurrence time (many years), as soon as the system returns to quiescence following its accretion outburst. Monitoring the thermal relaxation of the accretion-heated neutron star as it cools down in quiescence, allows us to probe various properties of the neutron star crust and core. By comparing these with results of transients that undergo accretion episodes of years to decades, we aim at probing possible physical differences induced by widely different outburst durations. In addition, we will test the recent theoretical conjecture that additional heating occurs in the outer layers of the neutron star crust.

Proposal Number: 10400425

Title: Photospheric radius-expansion bursts at high spectral resolution

PI Name: Duncan Galloway

It has been predicted that strong (a few hundred~eV EW) photoionisation edges might be present in the X-ray spectra at the peak of photospheric radius-expansion thermonuclear bursts. We propose to search for such features in bursts from sources uniquely known to exhibit frequent radius-expansion bursts. These observations will result in detection of up to 30 thermonuclear bursts, also providing a high signal-to-noise low-flux state spectrum, as well as allowing a detailed comparison of recurrence time and energetics with numerical ignition models. Detection of discrete features from the burst spectra may lead to highly-sought constraints on the compactness and hence the neutron-star equation of state.

Proposal Number: 10400447

Title: Crust Cooling of HETE J1900.1-2455 and Swift J1626.6-5156

PI Name: Nathalie Degenaar

We propose Chandra ToO observations of the two neutron star quasi-persistent X-ray binaries HETE J1900.1-2455 and Swift J1626.6-5156 in quiescence. Currently, both sources exhibit an outburst phase that started about 2.5 years ago. By studying the thermal relaxation of the neutron star crust following such a prolonged accretion episode, we can deduce stellar parameters such as the thermal conductivity and distribution of heating sources in the crust, as well as the neutrino emission mechanism operating in the core. Our targets are the only two quasi-persistent X-ray binaries that are known to exhibit X-ray pulsations and have high inferred magnetic fields. We want to explore the observational effects of strong magnetic fields on the thermal evolution of transiently accreting neutron stars.

Proposal Number: 10400448

Title: Bright edge-on LMXB transients to map ionized disk atmospheres

PI Name: Laurence Boirin

With the discovery of Fe XXV and Fe XXVI lines in several binaries viewed close to the disk plane, XMM and Chandra have revealed the existence of a highly-ionized atmosphere above the accretion disk. We have further demonstrated that the spectral changes during dips from dipping LMXBs, both in the lines and in the continuum could be explained by a decrease in the ionization level of this plasma. We want to investigate the presence of such a highly ionized plasma in four other binaries viewed close to the disk plane should these currently quiet transient sources turn on. We wish to constrain the plasma properties (location in binary, stationary or outflow) as a function of binary parameters (inclination, period) and luminosity.

Proposal Number: 10400459

Title: Deep search for the pulsars powering the TeV emission of LS I 61+303 and LS 5039

PI Name: Nanda Rea

We propose to observe with Chandsra ACIS in Continuous Clocking mode the two TeV emitters High Mass X-ray binaries LS I 61+303 and LS 5039, for 95 and 71ks, respectively. Aim of these Chandra observations is to address the long-standing puzzle on the nature of the compact objects hosted by these two TeV binaries, searching with unprecedented sensitivity for X-ray pulsations from these putative young rotational powered pulsars. As a nice by product we will also study the one-dimensional X-ray angular distribution searching (or, in the case of LS I 61+303, confirming with higher significance) for extended X-ray emission.

Proposal Number: 10400463

Title: Taking the temperature of the superburster 4U 1608-522 after an outburst

PI Name: Laurens Keek

Superbursts are rare thermonuclear flashes from accreting neutron stars. One condition for ignition is a sufficiently high temperature of the neutron star crust, which is heated during accretion. Most superbursts take place when the neutron star was accreting continuously above 10% of the Eddington limit for more then 10 years. In 2005 a superburst was observed from the transient system 4U 1608-522, when accretion started 55 days earlier. Crustal heating models predict a significantly lower temperature than the superburst models require. If the superburst models are correct in their prediction of a high temperature, crustal cooling is observable after an accretion outburst. We propose to observe 4U 1608-522 two times for 30 ks triggered after an outburst, to measure the cooling rate.

Proposal Number: 10400480

Title: Quasi-persistent neutron-star X-ray binaries in quiescence

PI Name: Rudy Wijnands

We propose to observe the next (quasi-)persistent neutron-star low-mass X-ray binary that turns off and becomes quiescent. This will provide an excellent opportunity to study the effects of prolonged accretion on the neutron-star properties (i.e., crust and core and thus the properties of ultra-dense matter) and the quiescent properties of low-mass X-ray binaries. Two follow-up observations taken several months later will provide important information about the time evolution of the quiescent properties. In particular, if indeed the quiescent X-rays are emitted by the crust, we will be able to study its evolution in time,thus setting strong constraints on the crust cooling models and the exact structure of the crust.

Proposal Number: 10400502

Title: ToO Observations of New Galactic Gamma-ray Transients Discovered with GLAST

PI Name: Dirk Pandel

The EGRET instrument on board CGRO discovered a unique transient event near the Galactic plane. The nature of this gamma-ray transient could never be established, and no clear counterpart at other wavelengths could be identified. The transient appears to represent a currently unknown class of gamma-ray emitting objects in the Galaxy. The GLAST gamma-ray observatory is expected to discover many new transient gamma-ray sources. Here we propose ToO observations of bright gamma-ray transients discovered by GLAST in the Galactic plane that are not associated with known blazars. The Chandra observations will enable us to precisely locate the transients for multi-wavelength follow-up observations, to determine their X-ray to gamma-ray flux ratio, and to measure their X-ray spectrum.

Proposal Number: 10400562

Title: Precise Chandra position determinations of compact binary candidates-faint persistent INTEGRAL sources in the bulge

PI Name: Mikhail Revnivtsev

Deep observations of the Galactic Center/Galactic bulge region with the INTEGRAL satellite have provided a statisticaly well-defined sample of faint persistent sources, the majority of which may be X-ray binaries with extremely low mass optical companions feeding the compact object via Roche lobe overflow. The optical emission of these low mass binary system should be extremely faint. Therefore, to make secure associations of an optical object with these X-ray sources, we require very accurate astrometric positions. We propose to obtain ``snapshot'' observations of a sample of such sources with the CHANDRA Observatory to obtain the best possible astrometric positions which will allow us to pursue follow up optical studies of this extremely rare class of objects. (Abridged)

Proposal Number: 10400572

Title: Variability in Quiescent Neutron Star Binaries in Dense Globular Clusters

PI Name: Craig Heinke

We propose to re-observe four rich globular clusters (Terzan 5, NGC 6388, NGC 6266, and NGC 6440), which have been previously observed by Chandra and found to contain 5 or more quiescent neutron star binaries with L_X>10^32 ergs/s. Our goal is to measure the years-timescale spectral and luminosity variability of the quiescent neutron star X-ray binaries seen in these clusters. Detecting variability in the thermal component of quiescent X-ray binaries would prove that accretion continues into quiescence, and that the thermal component can be produced by accretion. This study surveys seventeen quiescent X-ray binaries with sufficient sensitivity to draw strong conclusions about low-level accretion and the nature of the thermal component.

Proposal Number: 10400588

Title: Validating Neutron Star Radius Measurements

PI Name: Deepto Chakrabarty

Spectral analysis of non radius-expansion X-ray bursts and transient neutron star in quiescence were both used to estimate the NSs radii for different sources. The validities of the methods need to be verified by performing the radius measurements on the same source with different methods respectively. Transient type-I X-ray bursters are excellent candidates for testing the consistency between the methods, since they were detected in both bursts and quiescence. Out of 3 candidates: Cen X-4, Aql X-1 and 4U 1608-52, 4U 1608-52 turns out to be the best one due to the lack of archival RXTE burst data for Cen X-4 and the previous reported significant luminosity and temperature variability for Aql X-1 in quiescence. Therefore, we propose a 20 ks Chandra/ACIS-S observation of 4U 1608-52.

Proposal Number: 10400599

Title: The brightest unidentified Galactic sources of the new H.E.S.S. survey

PI Name: Omar Tibolla

In a survey of the Galactic plane performed in 2007, the High Energy Stereoscopic System(H.E.S.S.) discovered many new sources and most of them are still unidentified. We propose to use the Chandra X-ray Observatory to perform follow-up observations on two of the brightest newly discovered sources, HESS J1507-622 and HESS J1741-302, to identify the possible X-ray counterparts. Both sources have no clear positional counterparts: HESS J1507-622 does not show any counterpart at all, whereas an offset PWN is one of the possible explanations for HESS J1741-302. The aim is to obtain morphological and spectral information on the possible counterparts in order to understand the emission mechanisms of these 2 sources: the predicted X-ray flux is sufficient for detailed studies of these objects.

Proposal Number: 10400649

Title: Completing the Galactic Bulge Survey: categorising the plethora of faint X-ray sources in the Galactic Bulge

PI Name: Peter Jonker

We propose to image an area of 6x1 degrees centered on the Galactic Center at |b|=1.5 degrees: the Galactic Bulge Survey. 50% of this area will be observed in AO9. We here propose to complete the survey. These regions have been selected because of their lower extinction and crowding in the optical and near-infrared than in the Galactic Center area, while still having a high density of X-ray sources. We will detect a plethora of faint X-ray sources that will constrain binary evolution models by way of a number count and by identifying predicted X-ray binary types that so far have eluded identification. We expect to find (quiescent) eclipsing neutron star and black hole LMXBs. These are important for neutron star and black hole mass measurements.

Proposal Number: 10400745

Title: Hot on the Trail of Circinus X-1: The first X-ray jet from an accreting neutron star

PI Name: Sebastian Heinz

We propose to observe the pc-scale X-ray jet of the accreting neutron star Circinus X-1 during the source's current ultra-deep minimum state to obtain a high-fidelity image of the jet and determine the emission mechanism and spectral parameters of the jet. This will allow us to measure the jet power and to probe the physics of jet formation in neutron stars, and to investigate the interaction of powerful, ultra-relativistic jets from microquasars with the ISM. Reaching our science goals will require a 100ksec ACIS-S target-of-opportunity observation.

Proposal Number: 10400827

Title: The cooling neutron star in the super-Eddington accretor XTE J1701-462

PI Name: Jeroen Homan

Observing the cooling of neutron stars that are reheated by accretion provides new insights into neutron star structure. A detailed and efficient study of this cooling requires the use of Chandra. Here we propose to continue our ongoing monitoring campaign of the neutron star binary XTE J1701-462, a unique system that accreted at super- and near Eddington luminosities for more than 1.5 years before recently returning to quiescence. Our goal is to study the cooling of the surprisingly hot neutron star and also the evolution of the enigmatic non-thermal spectral component in unprecedented detail. Our ongoing strategy of frequent observations (every ~2.5 months) is necessary to test the most recent cooling models. We therefore request five ACIS-S observations for a total of 323 ks.

Proposal Number: 10400907

Title: Extended emission of microquasar LS 5039

PI Name: Gordon Garmire

Previous ACIS observations of LS 5039 have provided evidence of extended emission which consists of variable and possibly moving knots and a more compact asymmetric structure near the microquasar. However, the observations were either very short or the source was imaged very far off-axis. The poor statistics and the very broad off-axis PSF make it difficult to distinguish between intrinsically extended emission and emission produced by unresolved point sources. In a deeper, on-axis observation we will resolve these ambiguities, understand the nature of the variable knots, measure their motion, and study the asymmetric extended emission in the vicinity of LS 5039. This will help to understand the nature of LS 5039 and the mechanisms responsible for its high-energy emission.

Proposal Number: 10500002

Title: Measuring the Magnetic Fields of Central Compact Objects in Supernova Remnants

PI Name: Jules Halpern

X-ray timing studies of two X-ray pulsars in SNRs have detected no braking of their rotation, implying upper limits of 3E11 G on their surface dipole fields, well below those of ordinary young pulsars. We proposed that weak B-fields related to slow natal spin may be the physical basis of the class of Central Compact Objects (CCOs), including the unseen pulsar in SN 1987A. This proposal leverages existing timing data on CCO pulsars to determine if they are spinning down and, if so, to measure their magnetic fields by obtaining coherent timing solutions linking all previous data. Fields as small as 1E10 G can be measured in this way. Alternatively, accretion of supernova debris through a fallback disk may be occurring, which would be detectable as torque noise.

Proposal Number: 10500017

Title: Chandra Observation of the Southeast Rim of G347.3-0.5

PI Name: Stephen Murray

We propose an ACIS-I observation of the southeast shell of G347.3-0.5 in order to search for sharp nonthermal filaments and to establish a baseline for future expansion measurements.

Proposal Number: 10500031

Title: Search for a Period in the Cas-A CCO

PI Name: Stephen Murray

Looking for pulsation's from the Cas-A CCO

Proposal Number: 10500032

Title: Obtaining spatial and spectral information of a point source in RCW 86

PI Name: Jelle Kaastra

ROSAT found an unresolved source in the supernova remnant RCW 86, which may be the putative neutron star. However, the positional accuracy obtained with ROSAT and XMM-Newton are insufficient to see whether this source has an optical counter part (in which case it is likely to be a star or background source, rather than a neutron star). The source is located off center toward the SW of the remnant. The remnant is bright in the SW, so the source may be closer to the explosion center than expected based on the geometrical center. Chandra observed RCW 86 several times, but the point source was always outside the field of view. In one pointing on the SW, the source fell just in between the ACIS-I ACIS-S chip gaps. Here we propose to observe for a 2000 s in order to obtain an accurate position.

Proposal Number: 10500047

Title: Monitoring the spectral evolution of RXJ0720-3125 and determining its nature

PI Name: Jelle Kaastra

RX J0720.4-3125 belongs to a group of radio-quiet isolated neutron stars, whose spectra are characterized by a blackbody spectrum plus one or more broad absorption features. It is unique in that its blackbody temperature, and the depth of the absorption feature is variable. The cause for this spectral evolution is unclear, but one proposed model is free precession of a neutron star with two hot spots. Observing in this Chandra cycle will complete the coverage of a putative precession cycle with a period of~7-8 yr. This puts the precession hypothesis to the ultimate test.

Proposal Number: 10500050

Title: Observation of the central compact Object in RX J0852.0-4622

PI Name: Peter Predehl

We propose Chandra observations of the central compact object in RX J0852.0-4622.

Proposal Number: 10500065

Title: 2nd Epoch High Resolution Spectra of Cassiopeia A: Plasma Evolution and Doppler Mapping

PI Name: Claude Canizares

We propose to study the evolution of physical conditions in the bright X-ray ejecta of Cassiopeia A using a 2nd HETGS observation. Based on ACIS observations and plasma evolution models we expect to observe variations in the H- and He-like emission lines of Si and S. This will form an 8-year baseline to the 1st HETGS observation in 2001. We will also use these new data in conjunction with the 1st data set to map the 3-dimensional structure of the dynamically important X-ray ejecta.

Proposal Number: 10500072

Title: Galactic Supernova Remnant G340.6+0.3

PI Name: Gordon Garmire

We propose a 70 ks Chandra observation of SNR G340.6+0.3. This SNR shows distinctive X-ray line structures between N and S shells. Particularly, in the N region, strongly enhanced X-ray lines from highly ionized S, Ar, and Ca suggest ejecta-dominated emission, reminiscent of Cas A. The proposed Chandra observation is essential to reveal the nature of X-ray emission and the origin of this SNR.

Proposal Number: 10500078

Title: Long GRB Jet Breaks

PI Name: Gordon Garmire

In the standard fireball model for GRB afterglows, the jet opening angle can be determined from the achromatic jet break time by measuring the light curve until this break occurs. Swift XRT observations have shown that jet breaks are not observed in the first several days or weeks of a typical X-ray afterglow. This has important implications for the derived energetics of the GRB itself that cannot be resolved without a more complete sample of observed jet breaks. We propose to follow 4 carefully chosen long GRB afterglows with late-time Chandra observations in order to search for jet breaks occurring after the Swift observations end.

Proposal Number: 10500093

Title: Snap-shot survey of compact, radio-bright SNRs

PI Name: Gordon Garmire

We propose to observe a set of radio-bright remnants (SNRs) previously unobserved in X-rays. The SNRs have flat, non-thermal spectra suggesting efficient particle acceleration at the shock front. We also expect to find new pulsars or neutron stars within these remnants. These makes the selected SNRs good candidates for future TeV and GeV detections. The selected SNRs are also compact enough to be imaged within the ACIS-I field of view.

Proposal Number: 10500237

Title: Rediscovering the Young Ejecta-Dominated Supernova Remnant G350.1-0.3

PI Name: Patrick Slane

G350.1-0.3 is a small-diameter radio source whose complex morphology left it unclassified for years. Recent XMM observations make it clear that this is a young, bright ejecta-dominated SNR with an associated compact object. X-ray spectra reveal spatial variations in the ejecta abundances and ionization states, but the XMM resolution is insufficient to probe the emission on scales that are most relevant for investigating the ejecta structure. The poorly-measured position of the compact object also results in multiple candidate IR counterparts. We propose a Chandra observation of G350.1-0.3 to provide spectra of the ejecta on small spatial scales, to search for nonthermal filaments that are generally produced in young SNRs, and to obtain a high-precision position for the compact object.

Proposal Number: 10500274

Title: Chandra/Spitzer ToO Observations of a short-duration gamma-ray burst

PI Name: Kevin Hurley

We propose to observe a short GRB afterglow for 60 ks with Chandra, in conjunction with Spitzer observations. This is a continuation of a Spitzer/Chandra proposal which was accepted for Spitzer cycles AO-3 and AO-4, but never activated due to lack of a suitable burst. We have been granted Spitzer AO-5 ToO time until the cryogen runs out (2009 April 22), and are requesting Chandra time to support these observations. This is a multi-wavelength approach to the problem of understanding the short GRBs, involving two great observatories, as well as numerous ground-based facilities. By measuring the broad-band spectrum of the afterglow at several epochs, we can distinguish between the models proposed for the short bursts.

Proposal Number: 10500295

Title: Are all black widows alike?

PI Name: Vyacheslav Zavlin

We propose a Chandra observation of the eclipsing millisecond pulsar J2051-0827 in a 8.6 ks orbital period binary system with a low-mass companion. Optical observations have shown that this system is another example, in addition to PSR B1957+20, of a ``black widow pulsar'', whose relativistic pulsar wind ablates the stellar companion and creates an intrabinary shock. Studying the spectrum and light curve of the X-ray emission from the shocked relativistic wind provides an opportunity to elucidate the properties of the wind and understand the nature of this important class of millisecond pulsars.

Proposal Number: 10500298

Title: ToO Observations of Soft Gamma Repeaters

PI Name: Chryssa Kouveliotou

Soft Gamma Repeaters are rare sources of transient burst emission, probably magnetars (i.e. strongly magnetized neutron stars). Each of the SGRs has a persistent X-ray counterpart and some show coherent pulsations. During burst active phases, these counterparts undergo changes in their energy spectrum and pulse properties. Measuring the effects of burst activity are diagnostic of the burst mechanism and SGRs in general. In the event of detection of substantial burst activity from an SGR, we propose to make Chandra ToO observations of any of the four known sources, SGR 1900+14, SGR 1806-20, SGR 1627-41, SGR 0526-66, the two SGR candidates SGR 1801-23 and SGR 2013+34, as well as any newly discovered SGR source.

Proposal Number: 10500327

Title: An Extensive Study of the Youngest Galactic Supernova Remnant G1.9+0.3

PI Name: Stephen Reynolds

We have recently discovered that the smallest Galactic supernova remnant (SNR) in angular size, G1.9+0.3, is the youngest (known) Galactic SNR, with an age of about 100 years. The X-ray spectrum is lineless, well described by synchrotron emission with the highest rolloff frequency ever reported for a SNR. We propose a 500 ks Large Project observation of this unique object, which fills in a gap between SN 1987A (21 yr old) and Cas A (about 330). We wish to study detailed morphology, to compare with the 3 other Galactic synchrotron- dominated SNRs; spectra, to search for spatial variations and thermal emission; and variability, using this study for the first epoch. This object has enormous potential for the study of SNR hydrodynamics and strong-shock physics.

Proposal Number: 10500344

Title: New Pulsar Identifications of TeV Gamma-ray Sources

PI Name: Jules Halpern

Pulsar wind nebulae are the fastest growing class of Galactic TeV gamma-ray source as many unidentified HESS sources come to be identified with X-ray faint or "offset" PWNe. We propose to search for pulsations from new "TeV selected" pulsars seen in Chandra and XMM images of HESS sources. Determining pulsar ages and spin-down luminosities is important for testing models in which the TeV source is powered not by the supernova shell, but by inverse Compton scattering from high-energy PWNe electrons. Both the luminosity and the spatial extent of the TeV emission should depend on these basic pulsar spin parameters, as would the possible offset of the TeV nebula from the pulsar. These trends can be established by extending the observed sample.

Proposal Number: 10500347

Title: Searching for extragalactic soft gamma-ray repeaters

PI Name: Eran Ofek

The available observational evidence suggests that SGRs are highly magnetized (~10^14 G), young neutron stars. The best path to revealing the origin, evolution and formation channels of SGRs, is a detailed environmental study of a large sample of such objects. Unfortunately, current research of these objects is limited by the small number of known SGRs. We are planing to use GLAST/GBM in concert with Swift/XRT to identify SGR giant flares in nearby galaxies. However, in order to get arcsecond-accuracy locations of these events, which are needed for an environmental study, we ask for Chandra ToO of up to 2 events for which we will detect X-ray afterglows using Swift/XRT.

Proposal Number: 10500400

Title: Rapid Observations of Short Gamma-Ray Bursts: Accurate Positions Hold the Key to the Progenitor Population

PI Name: Edo Berger

Only 1/4 of all short GRBs are localized to sub-arcsecond accuracy, required for unambiguous host and redshift identifications, determination of the burst environment (disk, bulge, halo, IGM), and assessment of natal kicks. These properties determine the identity and ages of the progenitors, and the GRB explosion properties. Thus, much of our knowledge depends on a handful of events, which are moreover biased to high density environments by virtue of optical/UV/radio detections. Here we propose to double the fraction of events with sub-arcsecond positions, and overcome the density bias, using rapid Chandra observations of bursts with only Swift/XRT positions (3-6"). Swift data will guarantee Chandra detections at <4 days, and follow-up work will delineate the burst/host properties.

Proposal Number: 10500426

Title: PSRJ1832+0029: a unique target for pulsar emission physics

PI Name: Duncan Lorimer

We have discovered very unusual behavior in PSR J1832+0029, a 533-ms radio pulsar which switches between on and off states on timescales of several hundred days. Remarkably, the pulsar's spin-down rate almost doubles when the radio emission is on. This is even more dramatic than observed for PSR B1931+24 for which no satisfactory theory presently exists. Unlike PSR B1931+24, J1832+0029 is nearby (1.3 kpc) and an excellent target for X-ray detection. Here we request a 20 ks ACIS TOO to study the X-ray emission of PSR J1832+0029 in its off state, triggered by radio monitoring. Together with our recent GO observation, this TOO will help distinguish between radio emission quenching mechanisms that are either intrinsic to the pulsar or caused by accretion from an orbiting companion.

Proposal Number: 10500434

Title: Chandra Observations of New X-ray Supernovae

PI Name: David Pooley

We propose to continue our X-ray studies of Type II and Type Ib/c supernovae (SNe). The Swift satellite has ushered in a new era of studying SNe in the X-rays, obtaining densely sampled X-ray lightcurves for the first time. However, its spatial resolution is often not good enough to separate a SN from nearby sources. We propose short Chandra observations to alleviate this. These observations will assess the X-ray environment of newly discovered Swift SNe to determine any possible source confusion or contamination of the SN flux. Our strategy makes the best use of the capabilities of each observatory.

Proposal Number: 10500437

Title: The Spin and Magnetic Moment of the Neutron Star in Cassiopeia A

PI Name: Deepto Chakrabarty

How do the spin and magnetic moment of a neutron star relate to the properties of its massive progenitor and the supernova explosion? The best opportunity to study this question is the Cas A point source, the youngest known (300 yr) Galactic compact object. Its spectrum is unlike the classical Crab pulsar's, but is instead similar to both the more strongly magnetic "magnetars" and more weakly magnetic young pulsars. Much has been inferred about its progenitor and the supernova explosion from detailed studies of the supernova remnant. We propose to obtain a 500 ks HRC-S observation of the Cas A central point source, combining 350 ks of GO time and 150 ks of GTO time, in order to search for coherent pulsations down to the practical sensitivity limit of any current X-ray mission.

Proposal Number: 10500440

Title: Imaging the binary plerion

PI Name: George Pavlov

The radio pulsar B1259-63 is in an eccentric binary (e=0.87, P=3.4 yr) with a high-mass Be companion. Being dependent on binary orbital phase, the X-ray emission of this system is believed to be generated in a bow-shock pulsar wind nebula (PWN) formed by colliding winds from the pulsar and the companion. However, this very compact PWN has never been resolved in previous low-resolution observations. Imaging the B1259-63 PWN with the ACIS detector, we expect to detect a PWN tail, similar to those commonly observed behind solitary pulsars moving in the ISM with supersonic speeds, and a pulsar jet. Studying the properties of this unusual PWN will help to understand the nature of stellar and pulsar winds and their interaction.

Proposal Number: 10500481

Title: Prompt Study of Burst-Selected Outbursts from AXPs

PI Name: Gian Luca Israel

The discovery of transient AXPs has opened a new perspective in the field confirming that a relatively large number of members of this class has not been discovered yet, and suggesting that others would manifest themself in the future through outbursts. This proposal is aimed at gathering new insights on the physics of AXPs through the study of the very initial phases (within 10days) of their outbursts. In particular, we are proposing to select outbursts from known or still unknown magnetar candidates, to study them through fast-response (within hours) pointed observations and, therefore, to sample the still poorly explored phases of rapid timing/spectral variability just after the onset.

Proposal Number: 10500491

Title: An In-Depth Study of the Nearest Gamma-Ray Bursts

PI Name: Alicia Soderberg

Just a decade ago, astronomers thought stellar core-collapse was primarily a spherical process. Gamma-ray bursts, with collimated jets (powered by a central engine) and at the same time a spherical explosion (supernova) have upset this paradigm. Empirically there appears to be a wide range in the energy of the explosion. This opens up the possibility that "jet-driven" explosions are common in for all supernovae. Here we propose an in-depth study of the nearest gamma-ray bursts. Our synergistic multi-wavelength effort (radio, optical, Swift/XRT and proposed CXO) are designed to extract the true energy of these explosions.

Proposal Number: 10500533

Title: A Deep Chandra Observation of Supernova Remnant N49 in the LMC

PI Name: SANGWOOK PARK

N49 is a bright supernova remnant (SNR) in the Large Magellanic Cloud (LMC) showing complex substructures in X-rays, and thus is an excellent laboratory for the detailed study of the shock evolution in a clumpy environment. On the other hand, the origin (core-collapse vs thermonuclear explosion) of this SNR is unknown. Chandra ACIS observations provide a unique opportunity to study the metal-rich ejecta and shocked ISM, which will be useful to reveal the SNR origin and to study the detailed shock evolution process over a wide range of thermal states. Thus, we propose a 120 ks ACIS observation of SNR N49.

Proposal Number: 10500606

Title: X-ray emission from the double neutron star binary J1537+1155: Powered by the pulsar wind?

PI Name: Oleg Kargaltsev

We have discovered X-ray emission from the double neutron binary (DNSB) J1537+1155 in a 37 ks observation with Chandra. We found that the spectrum and the luminosity of J1537 are very similar to those of the famous double pulsar binary J0737-3039 (the only other DNSB detected in X-rays). However, unlike J0737, in J1537, whose orbit is more eccentric, we found evidence for variability with orbital phase, at a 3 sigma level. If confirmed, such variability proves that a substantial fraction of X-ray emission in DNSB can be produced via the interaction between the pulsar wind and the companion NS. We propose a follow-up 38 ks (one binary orbit) observation to verify the putative variability and test various models for X-ray emission of DNSBs.

Proposal Number: 10500627

Title: Time Variability of Synchrotron X-ray Emission in SNR RX J1713.7-3946

PI Name: Yasunobu Uchiyama

A recent detection of synchrotron X-ray variability in SNR RX J1713.7-3946 indicates that the interstellar magnetic field can be largely amplified at the expanding shock of a young SNR through magnetohydrodynamic waves generated by cosmic-rays themselves. Here we propose the follow-up Chandra ACIS-I observations of the northwestern shell of RX J1713.7-3946, with 3 x 30 ks monitoring observations, each spaced by 3-4 months. By tracking intra-year variability, we will infer the time history of electron acceleration and cooling. Also, by comparing with the previous observations, we will measure flux changes in lower brightness filaments as well as an expansion angular velocity, thereby testing the origin of TeV gamma-rays and predictions from a shock-acceleration theory.

Proposal Number: 10500639

Title: The Luminous Supernova Remnant in NGC4449: Charting the Future for SN 1987A

PI Name: Knox Long

The X-ray luminosity and the optical spectrum of the extraordinary young SNR in NGC4449 have changed since it was discovered in 1978. Here we propose to obtain a second-epoch Chandra ACIS S spectrum and contemporaneous optical (3300-7600 Ang) spectra of the SNR. We will compare the X-ray and optical spectra from different epochs and then model them to develop a more complete understanding of how the shock from this 50-100 year old SN is overrunning the circumstellar medium of the progenitor. We will use this to predict its future evolution and to compare this to the expected future of SN 1987A.

Proposal Number: 10500651

Title: X-ray observations of a TeV-emitting pulsar tail

PI Name: Zdenka Misanovic

A large number of recently detected TeV sources are still unidentified, although the attempts have been made recently to find their X-ray counterparts. For several of these extended TeV sources, young pulsars have been proposed as counterparts, although the pulsars are offset by 10-15 arcmin from the center of the TeV emission. The HESS source J1834-087 coincides with the shell SNR G23.3-0.3, which was proposed as its X-ray counterpart. However, we have recently detected a pulsar candidate and an elongated tail-like structure, possibly a PWN, at the SNR center. We argue that this PWN is a more likely HESS counterpart than the SNR shell. We propose a follow-up observation to confirm this identification.

Proposal Number: 10500659

Title: TINY HICCUPS TO TITANIC EXPLOSIONS: Tackling Transients in Anomalous X-ray Pulsars

PI Name: Victoria Kaspi

The past decade has seen major progress in neutron star astrophysics, with the discovery of magnetars in general, and the recognition that the Anomalous X-ray Pulsars (AXPs) fall in this class. AXPs have recently revealed surprising and dramatic variability behavior, which theorists have begun to show are highly constraining of physical models of magnetars, including their crusts, atmospheres, coronae and magnetospheres. In this proposal, we request Chandra/ACIS-S Target-of-Opportunity observations of one major Anomalous X-ray Pulsar (AXP) outburst in A10, in order to study in detail the evolution of the spectrum, pulsed fraction and pulse profile, for quantitative confrontation with recently developed models for the structure and electrodynamics of magnetars.

Proposal Number: 10500687

Title: A Deep Cycle 10 Chandra Observation of the Tycho Supernova Remnant

PI Name: John Hughes

We propose to obtain a very deep observation of the Tycho supernova remnant. Our observational goals include investigating the nature and origin of Fe-rich ejecta knots, and studying the spatial, spectral and temporal evolution of the nonthermal emission from the forward shock. Tycho is the ideal remnant for studies of cosmic-ray modified dynamics and for investigating key features of Type Ia supernova physics.

Proposal Number: 10500688

Title: Solving the Mystery of Type IIn Supernovae

PI Name: Poonam Chandra

X-ray observations of young supernovae provide unique constraints on the circumstellar density, profile, and elemental composition of the ejecta. Fingerprinting the exploded ejecta composition through X-ray spectroscopy can give clues to the mass and progenitor mass loss history of the exploding star. Both of these will help in understanding the relation of Type IIn progenitors to those of other classes of supernovae.

Proposal Number: 10500693

Title: The Weakly Magnetized Pulsar in Kes 79

PI Name: Jules Halpern

Our X-ray timing studies of two X-ray pulsars in SNRs detected no braking of their rotation, implying upper limits on their surface dipole fields well below those of ordinary young pulsars. We proposed that weak B-fields related to slow natal spin may be the physical basis of the class of Central Compact Objects (CCOs) including Cas A, and the unseen pulsar in SN 1987A. We propose to continue our timing program on the CCO pulsar PSR J1852+0040 in Kes 79 to determine if it is spinning down at all and, if so, to measure its magnetic field by obtaining a coherent timing solution linking all previous data. B-fields as small as 1e10 G can be measured in this way. Alternatively, accretion of supernova debris through a fallback disk may be occurring, which would be detectable as torque noise.

Proposal Number: 10500739

Title: A pulsar wind nebula in G18.95-1.1?

PI Name: Ralph Tuellmann

We propose to observe the central region of the composite SNR G18.95-1.1. Although this object has been extensively observed in the radio regime and to a minor extent in X-rays with ASCA and ROSAT, all searches for a point source have been unsuccessful. Our motivation to observe the G18.95-1.1 with Chandra is to detect an X-ray point source and perhaps non-thermal diffuse emission which could be the putative pulsar and its wind nebula. For this objective, high resolution observations are necessary to pinpoint the location of the source, making Chandra the only X-ray mission which with this study can be carried out.

Proposal Number: 10500753

Title: Chandra Cycle 10 Spatial and Spectral Monitoring of SNR 1987A

PI Name: David Burrows

Regular monitoring of SNR 1987A, the only supernova remnant in which we can study the early developmental stages in detail, is critical to testing models of remnant evolution, nonequilibrium ionization processes, and thin plasma spectra. SNR 1987A presents a unique opportunity to observe the birth and early evolution of a supernova remnant at high spatial and spectral resolution for the first time. We propose to continue our program of monitoring SNR 1987A in Cycle 10 at a roughly six month period.

Proposal Number: 10500758

Title: The High-B Radio Pulsar PSR J1718-3718: A Quiescent Magnetar?

PI Name: Maura McLaughlin

PSR J1718-3718 is a young radio pulsar with a magnetar-strength field. Its likely X-ray counterpart, which we serendipitously detected with Chandra, has a thermal spectrum resembling that of the transient AXP XTE J1810-197 in quiescence. Recently, a magnetar-like outburst was detected from rotation-powered PSR J1846-0248, showing that rotation-powered pulsars can exhibit magnetar behavior and suggesting that such activity may be correlated with magnetic field. With a magnetic field 50% higher than J1846-0258's, J1718-3718 may be a quiescent magnetar. We request ACIS-S observations to search for magnetar-like outbursts, detect X-ray pulsations, measure the pulsed fraction, improve the spectral parameters, and obtain a precise position in order to establish the nature of this source.

Proposal Number: 10500817

Title: The Unique Dynamical Vela Pulsar Wind Nebula

PI Name: George Pavlov

Chandra observations of the Vela pulsar-wind nebula (PWN) have revealed intriguing features in its structure and shown that the PWN brightness, shape, and spectrum change on a timescale as short as one week. Taking advantage of the known variability timescale, we propose a series of optimally sequenced observations to understand the PWN topology, dynamics, spectral structure, and interaction with the ambient matter.

Proposal Number: 10500822

Title: The Energetics and Environments of 'Naked' Supernovae

PI Name: Alicia Soderberg

Twenty years have passed since the peculiar class of SNe Ibc were recognized as core-collapse explosions. However, it is only recently that SNe Ibc have enjoyed a surge of interest thanks to their association with GRBs. Today, the most crucial question is whether SNe Ibc and GRBs arise from similar or distinct progenitor systems. Progress requires a detailed study of ordinary SNe Ibc, which out-number GRB-SNe by a factor of 100. Here we propose a focused program that leverages CXO data with those of Swift/XRT and VLA.

Proposal Number: 10500824

Title: A Deep HETG Probe of the CSM Interaction in SN1996cr

PI Name: Franz Bauer

SN1996cr is one of the closest and X-ray brightest SNe detected on the sky. Like SN1987A, it appears to have exploded into a wind-blown bubble, sparking a unique temporal evolution wherein its X-ray flux has increased for >8 years now. Serendipitous HETG data allow us to identify several strong, broad, asymmetric emission-line complexes in SN1996cr, although their low-signal leaves much to interpretation. We propose a deep HETG observation of SN1996cr to resolve these emission lines and elucidate their nature (velocity structure, line diagnostics, abundances). It is imperative to observe SN1996cr while it remains bright, as it is the only SN beside SN1987A where such an observation is practical and in many ways is more representative of CSM-interacting core-collapse SNe.

Proposal Number: 10500874

Title: Identifying the Nearest and Brightest Neutron Stars

PI Name: Derek Fox

Using catalog cross-correlation and over 400 ksec of Swift X-ray and UV observations, we have identified 19 candidate neutron stars from among the 18,811 sources of the ROSAT Bright Source Catalog. With one of these now confirmed as the eighth isolated neutron star, `Calvera,' we request Chandra observations of 16 remaining candidates to collect sub-arcsec positions and modest-quality X-ray spectra. Sub-arcsec X-ray positions are vital to confirm these objects as neutron stars by demonstrating the absence of optical counterparts to faint magnitudes (V > 25 mag). Chandra X-ray spectra will simultaneously yield blackbody temperatures and radii. This single program has the potential to dramatically increase the number of bright, nearby neutron stars that are known.

Proposal Number: 10500924

Title: AO-10 Observations of the Standard Candles Cas A and G21.5-09.

PI Name: CXC Calibration

We continue our annual observations of Cas A and G21.5-09 to monitor the HRC and ACIS.

Proposal Number: 10500927

Title: AO-10 Calibration Observations of E0102-72

PI Name: CXC Calibration

We have observed the oxygen rich supernova remnant E0102-72 every year since launch to monitor the low energy response of ACIS.

Proposal Number: 10610309

Title: Bondi accretion and jet power in a complete sample of elliptical galaxies

PI Name: Steven Allen

We have recently discovered a tight correlation between the Bondi accretion rate and kinetic jet power in nearby, X-ray bright elliptical galaxies with active central sources and clear radio bubbles. This correlation implies an instantaneous efficiency of ~2 per cent for the conversion of energy associated with the rest mass of accreted matter into jet power. Here we seek to address the time-averaged efficiency with which energy is fed back into the surrounding gas in elliptical galaxies. We propose Chandra X-ray observations of a complete optical magnitude, X-ray flux, X-ray luminosity and distance-limited sample of nearby elliptical galaxies. Our results will have important implications for models of gas accretion, jet formation and galaxy formation.

Proposal Number: 10610527

Title: The Baryons Content of the Most Massive Spiral Galaxy

PI Name: JOEL BREGMAN

Galaxies are missing most of their baryons when compared to the cosmological baryon to dark matter ratio. The Milky Way is missing at least 70% of its baryons while lower mass galaxies retain less than 10% of their baryons. Theory suggests that these baryons were expelled by intense galactic winds during the primary star formation period. These galactic winds carry gas far beyond the virial radius of small and modest galaxies, but the most massive galaxies should retain much of this gas. We propose to test this picture by searching for the missing baryons surrounding the very massive spiral galaxy, NGC 1961, which has 9 times the stellar content of M31 and with v_rot = 450 km/sec. If successful, we will measure the location and amount of its missing baryons.

Proposal Number: 10610698

Title: Search for Warm Dark Matter with Chandra Observations of Dwarf Spheroidal Galaxies

PI Name: Michael Loewenstein

The keV sterile neutrino is a dark matter (DM) candidate that may explain pulsar kicks and assist primordial star formation. Their radiative decay produces a photon amenable to X-ray study, and dwarf spheroidal galaxies are ideal targets because of their proximity, high DM density, and absence of additional X-ray sources. We propose Chandra observations of Willman 1 and Ursa Minor to complement our Suzaku program. Willman 1 is one of the faint, DM-dominated dwarf spheroidals newly discovered by the SDSS; none are observed in X-rays. Constraints based on these data enter a significant new regime: non-detections are still of great importance. In the best case, the long sought-after identity of DM will be discovered, pointing the way to physics beyond the Standard Model.

Proposal Number: 10610708

Title: Merger-Induced X-ray Emission in the Superantennae

PI Name: Andrew Ptak

We propose a 75 ksec Chandra exposure of one of the brightest nearby ULIRGs: the SuperAntennae. Previous observations revealed that this ULIRG harbors both a powerful starburst and a high-luminosity AGN. Suzaku and XMM-Newton spectra show that both neutral and ionized Fe-K lines are present. An exotic possibility is that some or all of the ionized Fe-K emission is due to the starburst. Here we propose to investigate this diffuse emission and constrain the contributions of the starburst and the AGN. These data will also give the strongest constraints to date for X-ray emission from the secondary nucleus, indicating to what extent a binary AGN may be present. These will provide new constraints for studying the impact of mergers and outflows on galaxy evolution.

Proposal Number: 10610747

Title: Dark Matter in Isolated Elliptical Galaxies

PI Name: David Buote

NGC 1521 and IC 4451 are isolated elliptical galaxies recently discovered in an XMM-AO6 pilot survey to search for optimal targets for X-ray studies of dark matter on the galaxy scale. We request modest follow-up observations with Chandra to map their dark matter profiles on the galaxy scale. These observations would be a key addition to the handful of elliptical galaxies which currently possess interesting X-ray constraints on their dark matter properties.

Proposal Number: 10610775

Title: Infant Ellipticals: the evolution of young merger-remnants

PI Name: Giuseppina Fabbiano

Studies of elliptical galaxies have revealed an intriguing population of young merger-remnant galaxies, which are found to be X-ray faint when compared to mature ellipticals. We propose to investigate the 1-3 Gyr post-merger period with 40 ks Chandra ACIS-S observations of 6 young post-mergers. With these observations, we will probe an important gap in the evolution of ellipticals by a) characterizing the evolution of their X-ray luminosity per unit mass, b) investigating their point source populations and c) observing how the diffuse emission evolves through the regeneration of hot gas halos. Such a study will further our understanding of the evolution of these remnants into ellipticals and will also allow us to investigate the scatter of X-ray properties in young post-mergers.

Proposal Number: 10610785

Title: Wide, deep and sharp: A comprehensive observation of M82, the exemplar of starburst activity

PI Name: David Strickland

We propose to observe M82, the exemplar of starburst and superwind activity, with a mosaic of deep ACIS-S observations that will cover the starburst region, the galactic disk and much of the extended superwind. The region of highest resolution (FWHM < 1.5") will cover the same field of view as recent deep HST and Spitzer observations. It will be the most data-rich X-ray study of a starburst galaxy ever (>1E6 counts), and will greatly advance our knowledge of the soft X-ray-emitting gas in the superwind, the very hot metal-enriched plasma within the starburst region, and the the X-ray point source population in both the starburst region and the galactic disk. It will further complement the investment made in observing M82 by the other Great Observatories, Hubble and Spitzer.

Proposal Number: 10610898

Title: A Chandra Study of Field Early-Type Galaxies

PI Name: John Mulchaey

Recent Chandra observations show that a large fraction of early-type galaxies in groups and clusters retain hot gas halos. However, the properties of these halos are consistent with the idea that they have been significantly reduced by environmental effects like ram-pressure stripping and evaporation. To quantify the importance of such mechanisms, we need to compare the properties of ellipticals in rich environments to those in the field where these mechanisms are not expected to be important. Unfortunately, very few field ellipticals have been observed by Chandra. We propose to rectify this situation by observing a sample of 9 nearby field early-type galaxies.

Proposal Number: 10620013

Title: X-Rays from Blue Compact Dwarf Galaxies

PI Name: Philip Kaaret

Blue compact dwarf galaxies (BCDs) provide a local analog to the heavy element deficient conditions under which early galaxy formation occurred. All of the low metallicity BCDs observed with Chandra or XMM-Newton show strong X-ray emission. We propose a survey of nearby, low metallicity BCDs which will enable us to determine if the ratio of X-ray luminosity to star formation rate in BCDs is different from that in normal galaxies. Calibrating this relation for conditions similar to early galaxy formation is essential to using X-ray luminosity as a star formation indicator at high redshift.

Proposal Number: 10620022

Title: Chandra Observation of a Dark Matter Galaxy in the Virgo Cluster

PI Name: Stephen Murray

A recent HI survey of the Virgo cluster detected several isolated HI clouds. One of these, VIRGOHI21, shows clear evidence of rotation in its HI spectrum: its properties are all typical for normal luminous galaxies. According to the Tully-Fischer relation, the galaxy should be of 12-th mag in V; yet, deep optical follow-up observations reveal a limit consistent with the sky background. VIRGOHI21 thus appears to be the first detection of a population of dark matter halos, or `dark' galaxies, often predicted by theory but whose detection has so far been elusive. We wish to test for the presence of diffuse X-ray emission associated with this dark galactic halo.

Proposal Number: 10620040

Title: Black Hole X-ray Novae in M31

PI Name: Stephen Murray

During A01-9 we found ~20 Black Hole X-ray Novae (BHXN) in M31 using Chandra, and with HST follow-up have estimated orbital periods for 9 of these. Observations are underway with HST to attempt to estimate additional periods. We propose to continue this program, both concentrating our scarce HST resources on a single transient which exceeds typical NS outburst luminosity. Only uninterrupted monitoring can yield the duty cycles and long-term light curves of BHXN (and other variables) in M31. Our GO+GTO programs have accumulated 790ks (ACIS+HRC) near the M31 bulge, and total Chandra exposure on M31 is now 940ks. By continuing our monitoring program through AO10 we will reach ~890ks on the bulge and >1Msec total Chandra M31 exposure.

Proposal Number: 10620091

Title: NGC 1232 population study

PI Name: Gordon Garmire

To study the source population in this spiral galaxy

Proposal Number: 10620402

Title: XMMU J134736.6+173403: the brightest ULX known?

PI Name: Peter Jonker

The X-ray source XMMU J134736.6+173403 has recently been discovered. Its X-ray position coincides with two interacting galaxies, one of which is a Seyfert II. The X-ray spectrum rules out an association with the Seyfert II. Carpano et al.(2008) suggest that the source is a foreground LMXB (unrelated to the galaxy-pair). Our optical photometry rule that out since the counterpart to the LMXB should have been detected. We find an extended source in the XMM error circle. Optical spectroscopy shows emission lines such as found in ULX nebulae. If this emission nebula is associated with the X-ray source it implies that it is the brightest known ULX. A 2 ks Chandra observation would provide the accurate source position necessary to assess if the nebula and the X-ray source are associated.

Proposal Number: 10620409

Title: Hyperluminous X-ray sources

PI Name: Timothy Roberts

Hyperluminous X-ray sources (HLXs) are the most luminous of all extra-nuclear X-ray sources in galaxies, with luminosities in excess of 10^41 erg/s. They are also exceedingly rare, with no more than a handful known, and constitute the best candidates amongst the ULX population to host IMBHs. Here, we propose 30-ks Chandra ACIS-S observations of two new candidate HLXs, discovered in the 2XMM serendipitous source catalogue. We will use a combination of the exquisite X-ray imaging of Chandra and X-ray variability data to determine whether the XMM-Newton detections are actually single accreting X-ray sources, and not e.g. an amalgamation of many fainter objects. We will also examine their X-ray spectra to place initial constraints on the accretion states of these extraordinary objects.

Proposal Number: 10620535

Title: Chandra Imaging of NGC 922 -- the closest collisional ring galaxy

PI Name: Andrea Prestwich

Ultra Luminous X-ray sources (ULX) have luminosities many times the Eddington limit for a stellar black hole and are associated with massive star formation. This is illustrated by the Chandra image of the Cartwheel, a collisional ring galaxy. The bulk of the X-ray luminosity is produced by 16 ULX co-incident with the outer ring of star formation. We request Chandra and HST time to image another collisional ring galaxy NGC 922. NGC 922 is similar to the Cartwheel, except that it is nearly three times closer and has higher metallicity. We will (1) detect fainter sources than was possible for the Cartwheel, (2) use archival HST data and our new H$\alpha$ images to associate X-ray sources with tracers of star formation and (3) study the effect of metallicity on the formation of ULX.

Proposal Number: 10620604

Title: The Most Luminous ULXs

PI Name: Douglas Swartz

We propose a census of the most luminous off-nucleus point-like X-ray sources by observing a sample of 7 high-star-formation-rate Arp interacting galaxy pairs. We expect to discover 30-50 new ULXs with luminosities >5e39 erg/s including as many as 20 above 2e40 erg/s. This represents up to a three-fold increase in the number of known ULX candidates above 1e40. This census will determine to high statistical significance whether or not there exists an upper limit to the luminosity of ULXs or if the power law slope of the luminosity function at lower luminosities continues unabated to higher values. This will have profound implications for the physics underlying the ULX phenomena, in particular for the mass distribution of accreting black holes.

Proposal Number: 10620720

Title: Monitoring M31 for BHXNe

PI Name: Michael Garcia

During A01-8 we found ~20 Black Hole X-ray Novae (BHXNe) in M31 using Chandra, and with HST follow-up have estimated orbital periods for 8 of these. Observations are underway with HST to attempt to estimate additional periods. We propose to continue this program concentrating our scarce HST resources on a single transient which exceeds 1e38 erg/s. Only uninterrupted monitoring can yield the duty cycles and long-term light curves of BHXNe (and other variables) in M31. Our GO+GTO programs will have accumulated 790ks (ACIS+HRC) near the M31 bulge by the end of AO9, and total Chandra exposure on M31 is now 940ks. By continuing our monitoring program through AO12 we will reach ~950ks on the bulge and >1Msec total Chandra M31 exposure.

Proposal Number: 10620790

Title: Multiwavelength Monitoring of the Spectral and Spatial Evolution of Sgr A* Flares

PI Name: Frederick Baganoff

We propose six 40-ks ACIS-I observations of the Galactic SMBH, SgrA*, with simultaneous NIR, submm, and mm monitoring. Our last two campaigns observed two flares simultaneously in the X-ray, NIR, and submm. We found a possible correlation between the X-ray to NIR flux ratio and the time lag of the submm peak in the two flares that can be explained with an adiabatically expanding relativistic plasma model. This project will test the proposed correlation and the expansion model for flare evolution; test the apparent overabundance of X-ray transients in the central pc; extend our survey of X-ray point sources to fainter fluxes; and measure the proper motion of variable Fe fluorescent features near SgrA* to test whether the SMBH was the irradiator, and hence more luminous in the recent past.

Proposal Number: 10620799

Title: Completing the Galactic Bulge Latitude Survey (BLS)

PI Name: Jonathan Grindlay

We propose to complete the Chandra Bulge Latitude Survey (BLS) of +/-1.5deg galactic latitude and +/-0.8deg in longitude about the Galactic Center. The BLS has already shown how the X-ray binary content of the Galactic Center Region matches on to that around the nucleus itself with the cycle 7 and 8 coverage obtained (cycle 9 data not yet obtained). The full survey will be analyzed for source spectra and variability and their distributions about the galactic center. IR photometry (JHK) will be completed with ISPI and optical imaging with Mosaic at the CTIO-4m for the full BLS region to constrain the identifications and nature of the sources. The BLS will provide a Chandra Legacy mosaic image and dataset for comparison with complementary surveys in the inner Galactic Bulge.

Proposal Number: 10700007

Title: The Disk-Jet Connection in Seyfert-1 AGN

PI Name: Jon Miller

A "fundamental plane'' of black hole activity has recently been found, possibly indicating that a specific disk-jet coupling governs all black holes. The potential importance of this relation demands that it be tested rigorously. Correlations between X-ray and radio flux are observed in individual stellar-mass black holes that bolster the robustness of the implied coupling. Similar correlations should hold in all black hole classes on the plane. We propose to make a careful search for correlated variability in the Seyfert-1 galaxy NGC 4051 via 10 short (10 ksec each) and contemporaneous Chandra and VLA observations. NGC4051 displays strong X-ray variability on the timescale of weeks and months, and has a moderately-bright radio core (0.5 mJy at GHz frequencies).

Proposal Number: 10700034

Title: X-ray spectroscopy of a recoiling SMBH candidate

PI Name: Peter Predehl

Recent numerical relativity simulations of coalescencing supermassive black hole (SMBH) binaries predict that SMBHs can receive kicks with velocities up to several thousand km/s due to anisotropic emission of gravitational waves. We have recently found the best candidate todate for such a recoiling SMBH (Komossa et al. 2008). We apply for a 25 ks ACIS-S exposure of this exceptional source.

Proposal Number: 10700038

Title: Longterm Monitoring of the Centaurus A Jet, ULXs, and Low Mass X-ray Binary Population

PI Name: Stephen Murray

We propose a 50 ks Chandra/ACIS-S and 4x5 ks ACIS-I observations of the nearby early-type galaxy Centaurus A to monitor the X-ray jet and X-ray binary population. We will search for proper motions of the X-ray knots, and continue our ongoing monitoring the X-ray fluxes and spectra for all the knots in the jet. The energy loss timescale of the synchrotron emission from the jet is of the order of years in the equipartition magnetic fields. In addition, we will observe the two known ULXs to determine their spectral states if active, and study the rest of the X-ray binary population down to an X-ray luminosity of 1E37 ergs/s in the 0.1-10.0 keV band. We will continue our monitoring campaign of the LMXB population to a sensitivity unmatched in any other early-type galaxy.

Proposal Number: 10700045

Title: Obtaining High Signal on the Fe-L Unresolved Transition Array

PI Name: Claude Canizares

We request 250 ksec of Chandra HETGS observations of the Seyfert 1 Ark 564. This source is known to have a broad range of ionized absorbers in outflow, seen against the strong soft continuum. The primary goal of these observations is to study the unresolved transition array (UTA) of Fe-L in this source, which provides the highest continuum level at the UTA of any previously studied active galaxy. We will also examine the response of the ionized warm absorber components to rapid variability, which is common in this source, a narrow line Sy1 galaxy. Finally, we will be able to place better limits on any narrow components of the neutral or ionized Fe emission lines.

Proposal Number: 10700069

Title: Flaring galaxies with strong emission-line light echo

PI Name: Peter Predehl

We propose two ACIS-S observations of the fading X-ray flare of the galaxy J0952+21 and one ACIS-S observation of the galaxy J1241+44. J0952+21 is unique in showing a very intense optical and NIR emission-line light echo in response to a high-energy flare which we also detected in the optical, NUV and NIR continuum (Komossa et al. 2008). The flare was likely caused by a stellar tidal disruption event. J1241+44 shows a similarly unusual optical emission-line spectrum, and we suspect a similar mechanism at work as in J0952+21.

Proposal Number: 10700080

Title: Studying the Optical and X-ray Emission Regions of Quasar PG 1115+080 by Monitoring Microlensing Events

PI Name: Gordon Garmire

We propose to apply the microlensing method to constrain the spatial structure of the optical and X-ray continuum emission regions of the quasar PG 1115+080 by comparing the flux ratios of the images in the X-ray and optical over several epochs. The differential changes in the flux ratios with wavelength will then constraint the relative sizes of the optical and X-ray emission regions.

Proposal Number: 10700081