Accepted Cycle 11 Observing Proposals

BH & NS BINARIES

Proposal Number	Subject Category	PI Name	Title
11400006	BH AND NS BINARIES	Kaastra	Chandra follow-up of weak persistent sources found in INTEGRAL maps
11400006	BH AND NS BINARIES	Kaastra	Chandra follow-up of weak persistent sources found in INTEGRAL maps
11400007	BH AND NS BINARIES	CHURCH	The mechanism of jet formation in Cyg X-2 and the nature of the hot ADC
11400012	BH AND NS BINARIES	Kaastra	Chandra follow-up of X-ray sources in interacting galaxies
11400037	BH AND NS BINARIES	Canizares	Observe Bright Atol Sources at High Mass Accretion Rates
11400046	BH AND NS BINARIES	Predehl	Confirming the Proper Motion of the Neutron Star in Puppis-A
11400085	BH AND NS BINARIES	Kaaret	An Irradiated Disk in an Ultraluminous X-Ray Source
11400118	BH AND NS BINARIES	Keek	Taking the temperature of the superburster 4U 1608-522 after an outburst
11400170	BH AND NS BINARIES	CORBEL	X-Ray Jets in Microquasars
11400172	BH AND NS BINARIES	Kong	A Chandra survey of quiescent black hole X-ray binaries
11400197	BH AND NS BINARIES	Paizis	INVESTIGATING NEW INTEGRAL SOURCES WITH CHANDRA
11400205	BH AND NS BINARIES	Nowak	Cygnus X-1 Viewed Outside of its Secondary's Wind
11400239	BH AND NS BINARIES	Guver	X-ray Column Density Towards the Low Mass X-ray Binary 4U 1702-429
11400250	BH AND NS BINARIES	Soleri	ToO observations of the microquasar GRS 1915+105 in quiescence
11400295	BH AND NS BINARIES	Miller	High Resolution Spectroscopy of a Black Hole Transient
11400306	BH AND NS BINARIES	Pooley	Transient LMXBs in Globular Clusters: More Numerous than We Thought?
11400329	BH AND NS BINARIES	Jonker	Following a black hole candidate X-ray transient to quiescence
11400331	BH AND NS BINARIES	Grenier	ToO observation of a bright Galactic transient discovered by Fermi and Swift
11400336	BH AND NS BINARIES	Chakrabarty	Spectroscopy of the Resurgent Ultracompact Binary 4U 1626-67
11400354	BH AND NS BINARIES	Degenaar	Crustal cooling of the neutron star in EXO 0748-676
11400372	BH AND NS BINARIES	Degenaar	The crust cooling of HETE J1900.1-2455
11400393	BH AND NS BINARIES	Patruno	Identifying the nature of the compact object in Swift J1753.5-0127
11400526	BH AND NS BINARIES	Levine	Precise Positions of Historically Bright X-ray Binaries
11400637	BH AND NS BINARIES	Migliari	Disk wind and jets in the neutron star binary GX9+9
11400651	BH AND NS BINARIES	Rutledge	Quiescent Low Mass X-Ray Binaries and Cataclysmic Variables in the Globular Cluster NGC 6304
11400669	BH AND NS BINARIES	Nowak	Deep Chandra Observations of the Black Hole LMC X-1
11400764	BH AND NS BINARIES	Lorimer	PSR J1023+0038: Tracing the Accretion History of a ``Missing Link'
11400785	BH AND NS BINARIES	Chakrabarty	Precise Localization of Transient Low-Mass X-ray Binaries
11400795	BH AND NS BINARIES	Laycock	X-Ray Binaries In a Nearby Star-Burst Galaxy: A New Lab for Astrophysics.
11400809	BH AND NS BINARIES	Homan	The cooling neutron star in the super-Eddington accretor XTE J1701-462
11400864	BH AND NS BINARIES	Xiang	Determining the Properties of Intervening Gas and Dust along the GX 17+2 Line-of-sight

Subject Category: BH AND NS BINARIES

Proposal Number: 11400006

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

PI Name: Jelle Kaastra

We propose to obtain a 2 ks 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).

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		INTEGRAL persistent weak ToO	ACIS-I	NONE	2
		INTEGRAL persistent weak ToO	ACIS-I	NONE	2

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		INTEGRAL persistent weak ToO	ACIS-I	NONE	2
		INTEGRAL persistent weak ToO	ACIS-I	NONE	2

Subject Category: BH AND NS BINARIES

Proposal Number: 11400007

Title: The mechanism of jet formation in Cyg X-2 and the nature of the hot ADC

PI Name: MICHAEL CHURCH

The Z-track source Cygnus X-2 has relativistic jets essentially in only one of its three states allowing us to find conditions at the inner disk needed for jet formation. The applicants recently made breakthroughs, proposing from continuum analysis a model for the Z-track and jet formation and secondly mapping highly ionized ADC line features around the Z indicating that the mass accretion rate increases in the sense opposite to that shown by the continuum. The crux of understanding the 3 states, jet formation and line formation in the ADC is finding the direction of Mdot increase and we propose to do this by obtaining the evolution of continuum and lines over a complete Z-track movement with XMM and Chandra.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
21:44:41.20	+38:19:18.00	Cygnus X-2	ACIS-S	HETG	72

Subject Category: BH AND NS BINARIES

Proposal Number: 11400012

Title: Chandra follow-up of X-ray sources in interacting galaxies

PI Name: Jelle Kaastra

We propose to obtain short exposures of a sample of unclassified sources that are found in interacting galaxies. 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. The ACIS sensitivity for hard sources is best while pile-up is not a major concern for source localization.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
08:53:12.40	+16:26:19.50	SDSSJ085312.3+162619	ACIS-S	NONE	2
13:51:54.10	+64:22:12.80	SDSSJ135154.1+642212	ACIS-S	NONE	4

Subject Category: BH AND NS BINARIES

Proposal Number: 11400037

Title: Observe Bright Atol Sources at High Mass Accretion Rates

PI Name: Claude Canizares

GX 13+1 has some history of line absorption in the Fe K region with XMM and Chandra. We want to confirm the existence of blue-shifted absorption, detect line flux and shift variability possibly in correlation with its spectral (banana) branch and source luminosity, as well as verify and investigate some unusual line detections ( i.e. Cr XXIV, Mn XXV). We employ a strategy of 5 x ~30 ks observations scattered over longer time spans with the goal to cover as much of the banana branch as possible. The ~30 ks length of each observation guarantees the same detection significance as in the existing observation.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
18:14:31.60	-17:09:26.70	GX 13+1	ACIS-S	HETG	29
18:14:31.60	-17:09:26.70	GX 13+1	ACIS-S	HETG	29
18:14:31.60	-17:09:26.70	GX 13+1	ACIS-S	HETG	29
18:14:31.60	-17:09:26.70	GX 13+1	ACIS-S	HETG	29
18:14:31.60	-17:09:26.70	GX 13+1	ACIS-S	HETG	30

Subject Category: BH AND NS BINARIES

Proposal Number: 11400046

Title: Confirming the Proper Motion of the Neutron Star in Puppis-A

PI Name: Peter Predehl

We propose to observe the Neutron Star in Puppis-A using the Chandra HRC-I to confirm its proper motion.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
08:21:57.50	-43:00:15.70	RXJ0822-4300	HRC-I	NONE	33.5

Subject Category: BH AND NS BINARIES

Proposal Number: 11400085

Title: An Irradiated Disk in an Ultraluminous X-Ray Source

PI Name: Philip Kaaret

Whether ultraluminous X-ray sources (ULXs) contain stellar-mass or intermediate-mass black holes is an important, but as yet unresolved question. We have discovered variable optical emission from the ULX NGC 5408 X-1 that we interpret as reprocessed emission in an irradiated disk. We propose simultaneous observations with Chandra and HST to test this interpretation and place constraints on the geometry of the accretion disk. The results should help determine the nature of the compact object.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
14:03:19.60	-41:22:58.50	NGC 5408 X-1	ACIS-S	NONE	36

Subject Category: BH AND NS BINARIES

Proposal Number: 11400118

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
16:12:43.00	-52:25:23.20	4U 1608-522	ACIS-S	NONE	60

Subject Category: BH AND NS BINARIES

Proposal Number: 11400170

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).

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		X-ray Jets	ACIS-S	NONE	150

Subject Category: BH AND NS BINARIES

Proposal Number: 11400172

Title: A Chandra survey of quiescent black hole X-ray binaries

PI Name: Albert Kong

We propose to detect quiescent X-ray emission and jets from three quiescent black holes, H 1705-250, GRS 1009-45, 4U 1543-47, with ACIS-S observations. Our proposed observations will allow us: 1) to test the prediction of the ADAF model to distinguish black hole and neutron star systems, and strengthen the evidence of the existence of event horizon; 2) to provide strong proof that accretion continues in quiescent black hole, and 3) to test if black hole systems require outflows.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:08:14.60	-25:05:29.00	H1705-250	ACIS-S	NONE	50

Subject Category: BH AND NS BINARIES

Proposal Number: 11400197

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		New INTEGRAL source 1	ACIS-S	HETG	20
		New INTEGRAL source 2	ACIS-S	HETG	20

Subject Category: BH AND NS BINARIES

Proposal Number: 11400205

Title: Cygnus X-1 Viewed Outside of its Secondary's Wind

PI Name: Michael Nowak

We propose to conduct a dedicated 30 ksec (0.06 of orbital phase) HETG observation of Cyg X-1 near orbital phase 0.5 (in TE mode, if reasonable). This orbital phase-dependent observation is designed to provide the greatest contrast with our existing dipping phase (orbital phase 0) observations, and thereby reveal the absorbing wind of the secondary at its minimum. The observation will allow us to view the secondary wind at its least dense, but most blueshifted points. Aside from further elucidating the structure of the wind, this will also give us our most unfettered view of the soft excess and Fe line region emanating from the black hole's accretion disk.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
19:58:21.70	+35:12:05.80	Cyg X-1	ACIS-S	HETG	30

Subject Category: BH AND NS BINARIES

Proposal Number: 11400239

Title: X-ray Column Density Towards the Low Mass X-ray Binary 4U 1702-429

PI Name: Tolga Guver

We request a 50 ks observation of the low-mass X-ray binary 4U 1702-429 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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:06:15.30	-43:02:08.60	4U 1702-429	ACIS-S	HETG	50

Subject Category: BH AND NS BINARIES

Proposal Number: 11400250

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 17-year-long outburst end during the 11th Chandra observing cycle. This system has never been observed in quiescence: its properties suggest that its quiescent X-ray luminosity 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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
19:15:11.60	+10:56:44.00	GRS 1915+105	ACIS-I	NONE	80

Subject Category: BH AND NS BINARIES

Proposal Number: 11400295

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		Black Hole Transient	ACIS-S	HETG	60

Subject Category: BH AND NS BINARIES

Proposal Number: 11400306

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:48:52.70	-20:21:37.00	NGC 6440	ACIS-S	NONE	2.5
17:48:04.90	-24:46:45.00	Terzan 5	ACIS-S	NONE	10
17:35:47.20	-30:28:54.00	Terzan 1	ACIS-S	NONE	10

Subject Category: BH AND NS BINARIES

Proposal Number: 11400329

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 request simultaneous Chandra/VLA TOO observations. The early part of the decay can be covered with approved Swift ToO and existing radio proposals.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		TOO	ACIS-S	NONE	157

Subject Category: BH AND NS BINARIES

Proposal Number: 11400331

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

PI Name: Isabelle Grenier

We propose a TOO observation of one bright Galactic transient detected by the Fermi 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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		Fermi Transient	ACIS-S	NONE	30

Subject Category: BH AND NS BINARIES

Proposal Number: 11400336

Title: Spectroscopy of the Resurgent Ultracompact Binary 4U 1626-67

PI Name: Deepto Chakrabarty

Chandra/XMM spectroscopy of this X-ray pulsar finds Doppler pairs of broad Ne and O emission lines, the first detection of a Keplerian line profiles in the X-ray. Recently, the 30-yr decline in X-ray intensity has reversed, with the source doubling in brightness in the past year along with a significant spectral change. We propose HETGS spectroscopy of this new bright state to use the emission line intensity and profiles to probe the geometry and physical conditions of the accretion flow, and also to constrain the unusual composition of the white dwarf donor. We will also make a first crude attempt to apply Doppler tomography to the strongest lines. These analyses may shed light on the bizarre pulsar torque reversal that accompanied the previous spectral change of the source in 1990.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
16:32:16.70	-67:27:42.00	4U 1626-67	ACIS-S	HETG	80

Subject Category: BH AND NS BINARIES

Proposal Number: 11400354

Title: Crustal cooling of the neutron star in EXO 0748-676

PI Name: Nathalie Degenaar

We propose two 30-ksec Chandra observations to continue our successful monitoring program of the crust cooling of the quasi-persistent neutron star X-ray transient EXO 0748-676. This source has recently started the transition to quiescence following an extended period of accretion that lasted more than 24 years. Studying the thermal relaxation of the accretion-heated neutron star provides the unique opportunity to test new theoretical conjectures that deal with the behavior of matter in the extreme density and pressure environment of the neutron star interior.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
07:48:33.80	-67:45:08.60	EXO 0748-676	ACIS-S	NONE	60

Subject Category: BH AND NS BINARIES

Proposal Number: 11400372

Title: The crust cooling of HETE J1900.1-2455

PI Name: Nathalie Degenaar

We propose a series of three 30-ksec Chandra ToO observations of the neutron star quasi-persistent X-ray binary HETE J1900.1-2455 once it returns to quiescence. Currently, the source undergoes an extended episode of accretion that started about 3.5 years ago. HETE J1900.1-2455 is the only quasi-persistent neutron star binary currently in outburst from which X-ray pulsations have been detected and that has a high inferred magnetic field. Studying the cooling of the accretion-heated neutron star once HETE J1900.1-2455 returns to quiescence provides an unique opportunity to investigate a variety of processes occurring under extreme density and pressure conditions. In particular, it allows us to test the possible effects of a high magnetic field on the thermal evolution of the neutron star.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
19:00:08.70	-24:55:13.70	HETE J1900.1-2455	ACIS-S	NONE	90

Subject Category: BH AND NS BINARIES

Proposal Number: 11400393

Title: Identifying the nature of the compact object in Swift J1753.5-0127

PI Name: Alessandro Patruno

We propose to observe the X-ray binary Swift J1753.5-0127 with a 30 ks observation, should the source end its current 4-year-long outburst. Despite several multi-wavelength monitoring campaigns, the nature of the compact object in the binary is still unknown. The system has been accreting matter at a relatively high rate (M_dot~10^-10 M_sun/yr) for more than 4 years. Current models predict a high quiescence luminosity (~10^32-10^33 erg/s) and clear signatures (thermal emission) of a heated crust, if the binary hosts a neutron star. If the system contains a black hole, such signatures will not be detected and the source will rapidly fade down to its predicted quiescent luminosity (~10^30-10^31 erg/s).

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:53:28.30	-01:27:09.00	Swift J1753.5-0127	ACIS-S	NONE	30

Subject Category: BH AND NS BINARIES

Proposal Number: 11400526

Title: Precise Positions of Historically Bright X-ray Binaries

PI Name: Alan Levine

We propose to obtain brief observations of historically bright sources which are or may be X-ray binaries in order to obtain precise X-ray locations. The sources are the HMXBs XTE J1543-568, 4U1901+03, and GS0834-430, the LMXB GS 0836-429, and the unclassified sources SAX J1428.6-5422, XTE J1837+037, and IGR J21117+3427. Precise locations are needed for the identification of optical/IR counterparts to five of these and for the confirmation of previously proposed optical/IR identifications of two of the sources. Precise locations are also used in the analysis of data from X-ray sky monitors. None of these sources is currently bright enough to be clearly detected by the RXTE ASM, but each could be sufficiently bright to be unambiguously detected in a Chandra/ACIS image.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
15:44:01.00	-56:45:54.00	XTE J1543-568	ACIS-I	NONE	1
19:03:37.10	+03:11:30.80	4U1901+03	ACIS-I	NONE	4
08:35:55.40	-43:11:11.80	GS0834-430	ACIS-I	NONE	1
08:37:23.60	-42:54:01.80	GS0836-429	ACIS-I	NONE	1
14:28:38.40	-54:22:22.80	SAX J1428.6-5422	ACIS-I	NONE	1
18:36:36.00	+03:42:00.00	XTE J1837+037	ACIS-I	NONE	1
21:11:47.50	+34:27:43.20	IGR J21117+3427	ACIS-I	NONE	1

Subject Category: BH AND NS BINARIES

Proposal Number: 11400637

Title: Disk wind and jets in the neutron star binary GX9+9

PI Name: Simone Migliari

We propose a 100 ks Chandra/HETGS observation of the bright neutron star low-mass X-ray binary (LMXB) GX~9+9, simultaneous with a 7 h radio observation with the VLA at 8 GHz. We will investigate the presence of X-ray narrow absorption/emission features in the Chandra spectra, which are a signature of a disk wind, and the connection of the wind with the presence of radio jet emission. The unique capabilities of Chandra/HETGS provide sufficient spectral resolution and sensitivity to study the detailed properties of the disk wind, its geometrical distribution and dynamics and its relation with the binary parameters. The VLA observations will probe the jet power as a function of the wind strength and plasma properties and the radio/X-ray flux relation in bright atoll NSs.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:31:44.20	-16:57:42.00	GX 9+9	ACIS-S	HETG	100

Subject Category: BH AND NS BINARIES

Proposal Number: 11400651

Title: Quiescent Low Mass X-Ray Binaries and Cataclysmic Variables in the Globular Cluster NGC 6304

PI Name: Robert Rutledge

The radii of neutron stars are now routinely measured in transient low-mass X-ray binaries (LMXBs) in globular clusters. Only a hand full of such systems are firmly identified, and more are needed to produce a usefully large population for constraining the dense matter equation of state. We propose here an observation of three X-ray sources in NGC 6304, recently spectrally classified as quiescent LMXBs. The primary goal of this proposal is to confirm the qLMXB nature of these sources by obtaining CCD-spectra to produce H-atmosphere radius measurements accurate to ~20-25 %. Confirming the classification of these sources may challenge the theory of binary formation in globular clusters. The secondary goal is a deep survey of the CV population in NGC 6304

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:14:32.90	-29:27:48.20	NGC 6304	ACIS-I	NONE	100

Subject Category: BH AND NS BINARIES

Proposal Number: 11400669

Title: Deep Chandra Observations of the Black Hole LMC X-1

PI Name: Michael Nowak

We propose Chandra-HETG observations of LMC X-1, totaling 150 ksec (3-5 separate observations). Our goals are to 1) search for spectroscopic evidence of (likely highly ionized) wind-fed accretion in this system, 2) accurately determine the column density and elemental abundances for this sightline (a combination of the LMC column and absorption local to the system, the latter of which might be variable), 3) carefully model the disk spectrum from 0.4-8\,keV, and 4) use the LMC X-1 spectrum to probe the warm/hot phases of the Galactic halo interstellar medium (ISM).

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
05:39:38.80	-69:44:35.70	LMC X-1	ACIS-S	HETG	150

Subject Category: BH AND NS BINARIES

Proposal Number: 11400764

Title: PSR J1023+0038: Tracing the Accretion History of a ``Missing Link'

PI Name: Duncan Lorimer

We propose to observe the recently discovered binary millisecond radio pulsar in the field of the Galaxy, PSR J1023+0038, that appears to be a long sought-after "missing-link" between low-mass X-ray binaries and radio millisecond pulsars. This binary, which has shown evidence for recent accretion, can serve as a unique laboratory for studies of the poorly understood transition mechanism of millisecond pulsars from accretion to rotation power. Resolving the spatial structure of any pulsar wind-driven nebular X-ray emission could reveal information regarding past accretion episodes in this system. Studying the non-thermal X-ray emission from within the binary may offer evidence for any remnant of an accretion disc interacting with the pulsar wind.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
10:23:47.70	+00:38:41.20	PSR J1023+0038	ACIS-S	NONE	86

Subject Category: BH AND NS BINARIES

Proposal Number: 11400785

Title: Precise Localization of Transient Low-Mass X-ray Binaries

PI Name: Deepto Chakrabarty

We propose to observe four neutron star or black hole soft X-ray transients (SXTs) in outburst to obtain accurate source positions, continuing a successful multi-year program in place since Cycle 6. These positions will allow reobservation of these sources in the X-ray, optical, and IR in order to study their quiescence 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 insufficient.

Target Name	Det.	Grating	Exp.Time
SXT 1	HRC-S	NONE	1
SXT 1	HRC-S	NONE	1
SXT 1	HRC-S	NONE	1
SXT 1	HRC-S	NONE	1

Subject Category: BH AND NS BINARIES

Proposal Number: 11400795

Title: X-Ray Binaries In a Nearby Star-Burst Galaxy: A New Lab for Astrophysics.

PI Name: Silas Laycock

We propose to study the population of High-Mass X-ray Binaries and Black-Hole X-Ray transients in a young Star-Burst. By means of regular monitoring, HMXBs will be identified during their regular outbursts at logLx>36 erg/s and orbital periods estimated for many. The optical novae accompanying BHXRTs brighter than LogLx>38 erg/s will be caught by HST to determine their binary parameters. Comparison with the Galaxy, M31 and the Magellanic Clouds will provide a direct and powerful demonstration of the role of age and environment in the evolution of the XRB populations of star forming galaxies, as a function of metallicity and star-formation rate.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
00:20:17.30	+59:18:13.60	IC 10	ACIS-S	NONE	105

Subject Category: BH AND NS BINARIES

Proposal Number: 11400809

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 successful 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 returning to quiescence. The goal of the Cycle 11 observations is to follow the cooling of the surprisingly hot neutron star in unprecedented detail and possibly catch the moment at which thermal equilibrium is reached; we also study the evolution of the enigmatic non-thermal spectral component. We reduce our sampling to two observations in Cycle 11 and request two 55 ks ACIS-S observations.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	55

Subject Category: BH AND NS BINARIES

Proposal Number: 11400864

Title: Determining the Properties of Intervening Gas and Dust along the GX 17+2 Line-of-sight

PI Name: Jingen Xiang

We propose a 40 ks (30 ks in TE mode followed by 10 ks in CC mode) Chandra-HETGS observation of the LMXB GX 17+2, to facilitate three independent science goals: (1) a determination of the composition and quantity of interstellar dust along the GX 17+2 line-of-sight (LOS) / in its environment, (2) a study of the size and spatial distribution of the dust grains along this LOS via X-ray scattering halo studies, and (3) a quantification of the extent to which CC-mode observations of bright binaries cannot be trusted for absorption column determinations.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
18:16:01.40	-14:02:11.00	GX 17+2	ACIS-S	HETG	40

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.