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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.

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The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2025. All rights reserved.