Accepted Cycle 13 Observing Proposals

BH & NS BINARIES

Proposal Number	Subject Category	PI Name	Title
13400045	BH AND NS BINARIES	Kaastra	A deep Chandra LETGS observation of the ultra-compact X-ray binary 4U 1543-624
13400083	BH AND NS BINARIES	Predehl	Proper Motion Measurement of the Central Compact Object
13400103	BH AND NS BINARIES	Nowak	A Further Drop into Quiescence by the Neutron Star and Possible Hierarchical Triple 4U2129+47
13400150	BH AND NS BINARIES	Paizis	INVESTIGATING NEW INTEGRAL SOURCES WITH CHANDRA
13400164	BH AND NS BINARIES	Kaaret	Constraining the mass of the black hole in IC 342 X-1 with simultaneous X-ray and radio observations
13400174	BH AND NS BINARIES	Keek	Taking the temperature of the superburster 4U 1608-522 after an outburst
13400186	BH AND NS BINARIES	Chakrabarty	Precise Localization of Transient Low-Mass X-ray Binaries
13400211	BH AND NS BINARIES	Corbel	X-Ray Jets in Microquasars
13400213	BH AND NS BINARIES	Grenier	ToO observation of a bright Galactic transient discovered by Fermi and Swift
13400215	BH AND NS BINARIES	Jonker	Following a black hole candidate X-ray transient to quiescence
13400239	BH AND NS BINARIES	Jonker	The unique opportunity to determine the mass of an accreting neutron star: an eclipsing accretion powered X-ray pulsar
13400265	BH AND NS BINARIES	Degenaar	Quiescent monitoring of the 11 Hz pulsar in Terzan 5
13400279	BH AND NS BINARIES	Jonker	Completing the Galactic Bulge Survey: categorizing the plethora of faint X-ray sources in the Galactic Bulge
13400312	BH AND NS BINARIES	Pooley	Transient LMXBs in Globular Clusters: More Numerous than We Thought?
13400320	BH AND NS BINARIES	Heinke	The Spectral Energy Distribution of a Very Faint X-ray Transient
13400401	BH AND NS BINARIES	Cackett	Investigating neutron star crustal cooling in MXB 1659-29
13400406	BH AND NS BINARIES	Homan	An accurate X-ray position of the neutron-star low-mass X-ray binary GX 3+1
13400434	BH AND NS BINARIES	McLaughlin	Constraining Neutron Star Close Binary Evolution with the ``Missing Link' PSR J1723--2837
13400498	BH AND NS BINARIES	Neilsen	Testing the Wind-Jet Connection in a Black Hole Transient
13400512	BH AND NS BINARIES	in 't Zand	Search for absorption edges in superexpansion bursts
13400618	BH AND NS BINARIES	Soria	Jets, hot spots and cocoon of the most powerful microquasar
13400639	BH AND NS BINARIES	Wijnands	Crust cooling of accretion heated neutron stars
13400681	BH AND NS BINARIES	Xiang	Measuring Emission Geometry, Interstellar Dust, and Distance with Chandra HETGS Observations of EXO 2030+375
13400697	BH AND NS BINARIES	Reynolds	The Luminosity of Quiescent Stellar Mass Black Holes
13400708	BH AND NS BINARIES	Xiang	A chandra HETGS study of 4U 1323-619: Binary Wind Properties, X-ray Burst, Distance and Studies of Interstellar Medium
13400741	BH AND NS BINARIES	Roberts	Chandra Observations of More New Black Widows and Redbacks in the Galactic Field
13400768	BH AND NS BINARIES	Cool	X-Ray Constraints on the Dynamical History of Omega Centauri
13400775	BH AND NS BINARIES	Grise	Constraining the irradiated disk and the nature of the companion star in an ultraluminous X-ray source
13400821	BH AND NS BINARIES	Pottschmidt	Filling the gap in understanding the wind structure of HDE 226868 / Cyg X-1
13400822	BH AND NS BINARIES	Homan	The cooling neutron star in the super-Eddington accretor XTE J1701-462
13400846	BH AND NS BINARIES	Homan	The shortest orbital period black-hole X-ray binary in quiescence
13400917	BH AND NS BINARIES	Linares	High-resolution X-ray spectroscopy of the thermonuclear burster and 11~Hz pulsar IGR J17480-2446
13400925	BH AND NS BINARIES	Morris	Identifying New qLMXBs in Milky Way Globular Cluster Cores

Subject Category: BH AND NS BINARIES

Proposal Number: 13400045

Title: A deep Chandra LETGS observation of the ultra-compact X-ray binary 4U 1543-624

PI Name: Jelle Kaastra

We propose to obtain a deep observation of the ultra-compact X-ray binary 4U 1543-624. The goal of this observation is twofold: to constrain the inner radius of the accretion disc using the recently discovered relativistically broadened O VIII Lyalpha line in this source, and to study the composition of the interstellar and circumstellar medium in the line of sight.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
15:47:54.70	-62:34:05.40	4U 1543-624	HRC-S	LETG	198.5

Subject Category: BH AND NS BINARIES

Proposal Number: 13400083

Title: Proper Motion Measurement of the Central Compact Object

PI Name: Peter Predehl

By making use of the sub-arcsecond angular resolution of the High Resolution Camera (HRC-I) aboard the Chandra X-ray Observatory we want to examine the central compact object (CCO) 1WGA J1713.4 3949 in the supernova remnant G347.3 0.5 for a possible proper motion. Using an archival ACIS-I observation and the proposed HRC-I observation which will span an epoch of about seven years we would be able to measure at least a recoil velocity of 500 km/s with a significance of ~3sigma. This would help us to better understand the nature of the central compact object in G347.3 0.5 and would put new constraints on core-collapse supernova models.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:13:28.80	-39:49:51.60	1WGA J1713.4 3949	HRC-I	NONE	39

Subject Category: BH AND NS BINARIES

Proposal Number: 13400103

Title: A Further Drop into Quiescence by the Neutron Star and Possible Hierarchical Triple 4U2129+47

PI Name: Michael Nowak

4U 2129+47 is a quiescent, eclipsing neutron star that has shown low temperature thermal emission (neutron star surface), a power law tail (unknown origin) and sinusoidally modulated absorption (disk). Our recent XMM observations indicate that the latter two components have disappeared, and that the soft X-ray flux has decreased by 40%. 4U 2129+47 may be part of a triple system, as is tentatively confirmed by XMM observations. The third body orbit, however, is not yet uniquely determined. We request three 22 ksec Chandra observations spread over 100 days to confirm the third body ephemeris. We also wish to measure the soft X-ray flux to determine whether 4U 2129+47 shows any evidence of further soft X-ray declines consistent with renewed neutron star cooling.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
21:31:26.20	+47:17:24.00	4U 2129+47	ACIS-S	NONE	66

Subject Category: BH AND NS BINARIES

Proposal Number: 13400150

Title: INVESTIGATING NEW INTEGRAL SOURCES WITH CHANDRA

PI Name: Adamantia Paizis

We propose to trigger a maximum of 2 Chandra medium (4-15 days) ToO observations on new sources discovered by INTEGRAL. 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 our 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 AO 5.

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: 13400164

Title: Constraining the mass of the black hole in IC 342 X-1 with simultaneous X-ray and radio observations

PI Name: Philip Kaaret

We recently discovered an unresolved radio source coincident with the ultraluminous X-ray source IC 342 X-1. The compact radio emission and the hard X-ray spectrum of the source suggest that it is a compact object accreting in the X-ray hard/radio loud state. This enables use of the fundamental plane relation found valid for stellar-mass to supermassive accreting black holes to constrain the compact object mass. We propose simultaneous Chandra and EVLA observations that will test interpretation of the unresolved radio emission as due to an outflow from an accreting black hole and provide the data needed for estimation of the black hole mass.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
03:45:55.70	+68:04:54.80	IC 342 X-1	ACIS-S	NONE	10

Subject Category: BH AND NS BINARIES

Proposal Number: 13400174

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: 13400186

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

PI Name: Deepto Chakrabarty

We propose to observe up to four neutron star or black hole X-ray transients in outburst to obtain accurate source positions, continuing a successful multi-year multiwavelength program in place since Cycle 6. These positions will allow reobservation of these sources in the X-ray, optical, IR, and radio bands in order to study their quiescent emission. This program will increase the number of accurately positioned X-ray transients, providing a more uniform sample for future work. We will only trigger our program for sources in crowded or highly obscured fields where a position from another (e.g., Swift) is insufficiently precise.

Target Name	Det.	Grating	Exp.Time
X-ray transient	ACIS-S	NONE	1
X-ray transient	ACIS-S	NONE	1
X-ray transient	ACIS-S	NONE	1
X-ray transient	ACIS-S	NONE	1

Subject Category: BH AND NS BINARIES

Proposal Number: 13400211

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: 13400213

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: 13400215

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. There are strong indications that the spectrum softens during the subsequent decay to the quiescent state, but this transition has not so far been resolved with enough signal-to-noise to fully quantify this effect. 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 6 simultaneous Chandra/EVLA 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	187

Subject Category: BH AND NS BINARIES

Proposal Number: 13400239

Title: The unique opportunity to determine the mass of an accreting neutron star: an eclipsing accretion powered X-ray pulsar

PI Name: Peter Jonker

Last year it was discovered that the peculiar transient SWIFT J1749.4-2807 exhibits pulsations at 518 Hz. Furthermore, it turned out that the source was eclipsing in a 8.8 hr orbit thereby holding the promise of a model independent neutron star mass determination. Optical or near-infrared dynamical studies offer the best prospects for constraining the neutron star equation of state, as they do not rely on any specific models concerning the neutron star itself. Unfortunately, the source position of SWIFT J1749.4-2807 is not well know at present. The unique focusing capabilities of Chandra provide the best chance to determine the source position and, via Gemini near-infrared imaging, we can locate the near-infrared counterpart of the source.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:49:31.80	-28:08:04.90	SWIFTJ1749.4-2807	ACIS-S	NONE	25

Subject Category: BH AND NS BINARIES

Proposal Number: 13400265

Title: Quiescent monitoring of the 11 Hz pulsar in Terzan 5

PI Name: Nathalie Degenaar

We propose two 50-ks Chandra observations of the globular cluster Terzan 5, to continue our monitoring of a recently discovered transient neutron star X-ray binary. A Chandra DDT observation carried out ~2 months after the cessation of the bright 2010 accretion outburst of this 11 Hz X-ray pulsar, detected the source elevated a factor ~4 above its quiescent emission level. This is most likely caused by significant heating of neutron star crust (due to accretion), which now needs to cool down until thermal equilibrium with the core is re-established. Monitoring the crust cooling yields important insight into the neutron star properties. It is the first time that such studies are performed for a transient neutron star X-ray binary with an outburst duration of only weeks.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:48:05.20	-24:46:47.30	Terzan 5	ACIS-S	NONE	100

Subject Category: BH AND NS BINARIES

Proposal Number: 13400279

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

PI Name: Peter Jonker

We propose to image the remaining part of the Galactic Bulge Survey. The GBS 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. In the 72% of the area that we have observed so far we have detected a plethora of faint X-ray sources. The goals of the GBS are: i) to constrain binary evolution models, especially the common envelope theory by way of a number count, ii) use (quiescent) eclipsing neutron star and black hole LMXBs for model independent mass-measurements iii) determine the projected spatial distribution of (q)LMXBs to investigate LMXB formation scenarios.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:49:51.10	-30:42:16.90	GBS13-2	ACIS-I	NONE	22
17:56:46.60	-28:32:28.20	GBS13-3	ACIS-I	NONE	22
17:50:55.70	-30:42:25.90	GBS13-4	ACIS-I	NONE	22
17:45:54.00	-32:06:10.00	GBS13-5	ACIS-I	NONE	20
17:32:55.70	-30:29:51.40	GBS13-6	ACIS-I	NONE	14
17:55:43.30	-28:32:30.70	GBS13-1	ACIS-I	NONE	22
17:57:20.10	-27:07:50.40	GBS13-7	ACIS-I	NONE	2
17:47:20.20	-25:48:22.90	GBS13-8	ACIS-I	NONE	2

Subject Category: BH AND NS BINARIES

Proposal Number: 13400312

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: 13400320

Title: The Spectral Energy Distribution of a Very Faint X-ray Transient

PI Name: Craig Heinke

Very faint X-ray transient accretion states (peak L_X < 10^36 ergs/s) are hard to explain with standard theories of disk instabilities. The unusual globular cluster transient M15 X-3 has only been seen at Lx~6e33 and at 2-6e31 ergs/s. We aim to determine the nature of the companion star through near-simultaneous Chandra and HST imaging, measuring its X-ray spectrum and optical colors.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
21:29:58.10	+12:09:40.10	M15 X-3	ACIS-S	NONE	5

Subject Category: BH AND NS BINARIES

Proposal Number: 13400401

Title: Investigating neutron star crustal cooling in MXB 1659-29

PI Name: Edward Cackett

We propose a 100 ksec observation of the quasi-persistent neutron-star low-mass X-ray transient MXB 1659-29 in quiescence. The long outburst from 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 in 2001. The most recent observation suggests that the crust may now be thermally relaxed. However, with only one data point and recent evidence of residual accretion during quiescence in other objects, a further observation is needed to determine decisively whether cooling has ceased or may continue. This observation will further constrain models for the neutron star crust and core, and will test whether residual accretion is important.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:02:06.50	-29:56:44.10	MXB 1659-29	ACIS-S	NONE	100

Subject Category: BH AND NS BINARIES

Proposal Number: 13400406

Title: An accurate X-ray position of the neutron-star low-mass X-ray binary GX 3+1

PI Name: Jeroen Homan

We request a 1 ks Chandra HRC-I observation of the neutron-star low-mass X-ray binary (NSXB) GX 3+1. This source is the only member of the bright persistent NSXBs in our Galaxy for which an optical or near-infrared counterpart has not yet been identified. An accurate X-ray position will allow us to distinguish between several proposed near-infrared counterparts. This, in turn, will enable follow-up spectroscopic studies to determine the nature of the donor star in GX 3+1.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:47:56.10	-26:33:48.80	GX 3+1	HRC-I	NONE	1

Subject Category: BH AND NS BINARIES

Proposal Number: 13400434

Title: Constraining Neutron Star Close Binary Evolution with the ``Missing Link' PSR J1723--2837

PI Name: Maura McLaughlin

We propose an observation of the recently discovered binary millisecond pulsar (MSP) J1723-2837, which is a likely "missing-link" between low-mass X-ray binaries and radio MSPs. The unmatched angular resolution of Chandra will allow us to detect and characterize the X-ray bow shock or tail emission likely present near the pulsar in order to probe its accretion history. Evidence of past pulsar wind activation and accretion episodes may be manifested through irregularities or discontinuities in the nebular X-ray emission associated with the pulsar. As the nearest object of its kind and only the second to be found in the field of the Galaxy, J1723--2837 offers the best opportunity to study key unknowns regarding close binary evolution of neutron stars as well as the physics of MSP winds.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:23:23.20	-28:37:57.10	PSR J1723-2837	ACIS-S	NONE	55

Subject Category: BH AND NS BINARIES

Proposal Number: 13400498

Title: Testing the Wind-Jet Connection in a Black Hole Transient

PI Name: Joseph Neilsen

We propose a sequence of four 30 ks HETGS observations of a bright black hole transient in outburst for a targeted study of the interaction between accretion disk winds and relativistic jets. While global studies of high-resolution X-ray spectra of BHXRBs hint that strong, highly-ionized winds tend to coincide with the disappearance of compact jets, our focused study of GRS 1915+105 indicates that winds may be directly responsible for quenching jets. By carefully tracking the strengths of the wind and the jet (supported by the world's premiere radio and infrared facilities), we will perform the first systematic test of the wind-jet interaction around a black hole. Thus we will reveal whether winds truly play a pivotal role in the dynamical evolution of black hole accretion flows.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		Black Hole Transient	ACIS-S	HETG	120

Subject Category: BH AND NS BINARIES

Proposal Number: 13400512

Title: Search for absorption edges in superexpansion bursts

PI Name: Jean in 't Zand

Our goal is to measure with the LETGS a series of bright type-I X-ray bursts with strong photospheric radius expansion ('superexpansion'), search for absorption edges due to the ashes of nuclear burning and, if succesful, attempt a measurement of the gravitational redshift. The target, 4U 1820-30, is an ultracompact X-ray binary whose bursts are known to consistently show strong expansion. The bursts only occur in the quasi-periodic low accretion states. We request a quick TOO, to be triggered by either RXTE-ASM or ISS-MAXI, with a total exposure time of 100 ks to obtain the detection of about 10 bursts.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
18:23:40.50	-30:21:40.00	4U 1820-30	ACIS-S	LETG	100

Subject Category: BH AND NS BINARIES

Proposal Number: 13400618

Title: Jets, hot spots and cocoon of the most powerful microquasar

PI Name: Roberto Soria

S26 is the most powerful microquasar known to date: an accreting black hole in a nearby galaxy dominated by jet power even at near-Eddington accretion rates. From archival Chandra data, we discovered a pair of X-ray hot spots, proof of the interaction of the collimated jets with the ISM. With a new observation, we will: a) model the spectrum of the hot spot and shock-ionized nebula emission; b) constrain the fraction of jet power transferred to the X-ray-emitting plasma; c) determine the accretion state and luminosity of the central black hole. For the hot spots, we will distinguish between thermal and non-thermal emission, measure the electron temperature and test shock models. The new data will greatly advance our multiband study of the jet lobes, nebula and core of this system.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
23:57:59.90	-32:33:20.90	S26 in NGC 7793	ACIS-S	NONE	150

Subject Category: BH AND NS BINARIES

Proposal Number: 13400639

Title: Crust cooling of accretion heated neutron stars

PI Name: Rudy Wijnands

We propose to continue our successful program to use the observed cooling of the crusts in accreting neutron star systems to probe the properties of ultra-dense matter. Those crusts are heated due to the accretion of matter on to neutron stars during the X-ray outburst and after the outbursts are over the crusts should cool down until they are in equilibrium with the core again. Following this cooling processes in several systems has already given us new insights in the structure of neutron stars (i.e., the crust but also the core and hence in ultra dense matter), but many uncertainties remain. Therefore it is needed to enlarge our sample of well studied sources to obtain better insights in the behavior of how neutron stars react to the accretion of matter.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
		Quiescent source	ACIS-S	NONE	150

Subject Category: BH AND NS BINARIES

Proposal Number: 13400681

Title: Measuring Emission Geometry, Interstellar Dust, and Distance with Chandra HETGS Observations of EXO 2030+375

PI Name: Jingen Xiang

We propose a 60~ks Chandra-HETGS observation of EXO 2030+375 during a normal outburst to facilitate three science goals: (1) study the photoionization geometry of the emission line regions via time-resolved grating spectroscopy, (2) determine the size and spatial distributions of dust along the line of sight via the dust scattering halo, (3) measure geometrical distance to EXO 2030+375 using time delays between the lightcurves of the point source and the dust halo.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
20:32:15.30	+37:38:14.90	EXO 2030+375	ACIS-S	HETG	60

Subject Category: BH AND NS BINARIES

Proposal Number: 13400697

Title: The Luminosity of Quiescent Stellar Mass Black Holes

PI Name: Mark Reynolds

The defining property of a black hole is its event horizon. Previous Chandra observations have revealed the quiescent X-ray luminosity of the Galactic stellar mass black holes to be systematically less luminous (by factors of ~ 100) than neutron star binaries at similar orbital periods. In cycle 12, we observed the stellar mass black hole GS 1354-64 and found it to be at a luminosity of ~ 1e34 erg s^{-1} (~ 1e-5 L_{Edd}), over an order of magnitude greater than expected and in conflict with the known distribution of quiescent black hole luminosities. Here, we propose to use Chandra to investigate the stability of the quiescent accretion luminosity from GS 1354-64.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
13:58:09.70	-64:44:05.20	GS 1354-64	ACIS-S	NONE	40

Subject Category: BH AND NS BINARIES

Proposal Number: 13400708

Title: A chandra HETGS study of 4U 1323-619: Binary Wind Properties, X-ray Burst, Distance and Studies of Interstellar Medium

PI Name: Jingen Xiang

We propose five 30 ks Chandra-HETGS observations of 4U 1323-619, a dipping and bursting LMXB, to facilitate four science goals: (1) a study of the geometry of the emission and absorption line regions via the evolution of photoionized emission and absorption line spectroscopy, (2) a study of known frequent X-ray bursts, which are attributed to unstable nuclear burning, and (3) a study of the X-ray scattering halo in order to determine the spatial distribution of the dust grains, (4) determine the source geometrical distance via time delays of the halo photons.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
13:26:36.10	-62:08:10.00	4U 1323-619	ACIS-S	HETG	150

Subject Category: BH AND NS BINARIES

Proposal Number: 13400741

Title: Chandra Observations of More New Black Widows and Redbacks in the Galactic Field

PI Name: Mallory Roberts

There has recently been a large increase in the number of known eclipsing radio millisecond pulsars in the Galactic field, many of which are associated with Fermi gamma-ray sources. All are in tight binaries (P_b < 24hr) many of which are classical "black widows" with very low mass companions (M_c << 0.1 M_sol) but some are "redbacks" with probably non-degenerate low mass companions (M_c ~ 0.2 M_sol). We request Chandra observations over full orbits of four of these new pulsars in order to determine the X-ray emission from any intrabinary shock and to search for compact wind nebulae.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
11:24:01.10	-36:53:22.00	PSR J1124-36	ACIS-S	NONE	22
20:47:08.90	+10:53:09.20	PSR J2047+10	ACIS-S	NONE	23
18:16:30.20	+45:10:15.00	PSR J1816+45	ACIS-S	NONE	35
16:28:08.20	-32:02:60.00	PSR J1628-32	ACIS-S	NONE	20

Subject Category: BH AND NS BINARIES

Proposal Number: 13400768

Title: X-Ray Constraints on the Dynamical History of Omega Centauri

PI Name: Adrienne Cool

As the largest globular cluster in the Galaxy, Omega Cen has been a prime target for searches for an intermediate-mass black hole. Cycle 1 Chandra observations, combined with HST imaging, also show that Omega Cen is host to a wide variety of X-ray emitting binary stars, including more than 20 cataclysmic variables. We propose a deep 230 ksec ACIS-I exposure which, combined with existing data, will enable us to (1) make the most sensitive X-ray search to date for an IMBH in a globular cluster, to a limiting Lx = 5x10^29 erg/s; (2) complete a census of CVs in the cluster for comparison to populations in dense clusters to elucidate their origins; (3) conduct an X-ray search for millisecond pulsars, to investigate the surprising absence of radio MSPs detected in Omega Cen to date.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
13:26:47.20	-47:28:46.50	NGC 5139	ACIS-I	NONE	230

Subject Category: BH AND NS BINARIES

Proposal Number: 13400775

Title: Constraining the irradiated disk and the nature of the companion star in an ultraluminous X-ray source

PI Name: Fabien Grise

Previous HST observations of the ultraluminous X-ray source Holmberg IX X-1 show that its optical emission may be dominated at short wavelengths by an irradiated accretion disk and at long wavelengths by a late-type (super)giant star which would be the donor star in the system. This makes of Holmberg IX X-1 one of the few ULXs where we have a direct, observational hint about the presence of a companion star. We propose X-ray and UV to NIR observations with Chandra and HST/WFC3. The X-ray spectrum will be essential at modeling the disk emission and, combined with UV/optical measurements, will allow us to constrain the irradiation in the disk. Longer wavelengths will enable us to definitely identify the red excess emission as coming from the donor star or from some structure from the disk.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
09:57:53.30	+69:03:48.10	Holmberg IX X-1	ACIS-S	NONE	15

Subject Category: BH AND NS BINARIES

Proposal Number: 13400821

Title: Filling the gap in understanding the wind structure of HDE 226868 / Cyg X-1

PI Name: Katja Pottschmidt

We propose to observe the BH HMXB system HDE 226868 / Cyg X-1 with Chandra-HETGS for 24 ks (corresponding to Delta phi=0.05 in orbital phase) between orbital phases phi=0.25 and phi=0.4. The spectroscopic analysis of the highly photoionized wind during this phase will improve our understanding of the wind, its implications for the accretion flow onto the black hole, and also of the conditions necessary for the formation of a narrow Fe K fluorescence line. In addition, cessation of dipping is expected during this phase. If seen, the morphology and spectral signatures of the last dips will constrain the location and kinematics of the wind structures responsible for these absorption events.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
19:58:21.70	+35:12:05.80	Cygnus X-1	ACIS-S	HETG	24

Subject Category: BH AND NS BINARIES

Proposal Number: 13400822

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

PI Name: Jeroen Homan

Observing the cooling of neutron stars reheated by accretion provides new insights into neutron star structure. Using Chandra and XMM we have followed in unprecedented detail the cooling of the neutron star transient XTE J1701-462, a unique system that accreted at super- and near-Eddington luminosities for more than 1.5 years before returning to quiescence. A recent observation indicates that the source is probably still cooling; here we propose to continue our successful monitoring of the source and constrain the late phase of cooling with a 65 ks observation at the end of Cycle 13. This will extend our tracking of the source from approximately 3 years to 5 years into quiescence and will likely allow us to distinguish between different models for the overall cooling curve.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	65

Subject Category: BH AND NS BINARIES

Proposal Number: 13400846

Title: The shortest orbital period black-hole X-ray binary in quiescence

PI Name: Jeroen Homan

We propose Chandra observations of MAXI J1659-152, the shortest orbital period black hole X-ray binary. Observing the source in quiescence will serve two purposes. 1) The short orbital period of MAXI J1659-152 allows us to extend the comparison between quiescent neutron stars and black holes to orbital periods that, until recently, were only covered by neutron star systems. This will provide us with further insight in the differences between the radiatively inefficient flows in both types of systems. 2) It will also allow us to test whether there exists a minimum luminosity for quiescent black hole systems, as predicted by binary evolution theory. Based on a distance estimate of 4.5 kpc we expect to be able to detect MAXI J1659-152 down to a luminosity of 1.5e30 erg/s in 80 ks with ACIS-S.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
16:59:01.70	-15:15:28.40	MAXI J1659-152	ACIS-S	NONE	80

Subject Category: BH AND NS BINARIES

Proposal Number: 13400917

Title: High-resolution X-ray spectroscopy of the thermonuclear burster and 11~Hz pulsar IGR J17480-2446

PI Name: Manuel Linares

Atomic features formed on the neutron star surface give a direct measurement of the neutron star compactness and long-sought information on the equation of state of ultradense matter. Rotational broadening of spectral lines formed on fast-spinning neutron stars hampers the detection of such features. We propose Chandra high-spectral-resolution observations of a recently discovered prolific source of thermonuclear bursts. The atypically slow spin of this source reduces rotational broadening drastically and offers a unique opportunity to measure how compact this neutron star is.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:48:04.80	-24:46:48.80	IGR J17480-2446	ACIS-S	HETG	100

Subject Category: BH AND NS BINARIES

Proposal Number: 13400925

Title: Identifying New qLMXBs in Milky Way Globular Cluster Cores

PI Name: David Morris

Quiescent low mass X-ray binaries (qLMXBs) in Milky Way globular clusters (MWGCs) are a powerful probe of the dense matter equation of state (EoS). Through a Swift-XRT snapshot survey of MWGCs we have discovered candidate qLMXBs in the cores of NGC6717 and NGC6287. Chandra's arcsecond spatial resolution is now required to separate the blended sources discovered in these MWGCs. The observations proposed with Chandra ACIS-S will constrain the spectral parameters of the qLMXBs in NGC6717 and NGC6287 to 20%, which will determine whether they occupy a region of NS mass-radius parameter space which strongly constrains the NS EoS. If they do, they can rule out up to 75% of the remaining allowed NS EoS and subsequent Chandra observations will be proposed to fully exploit them.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
18:55:06.00	-22:42:05.30	NGC6717	ACIS-S	NONE	20
17:05:09.10	-22:42:30.10	NGC6287	ACIS-S	NONE	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 © 1998-2024. All rights reserved.