Chandra Large, Very Large and X-ray Visionary Projects

BH & NS BINARIES

Proposal Number	Subject Category	PI Name	Type	Time (ks)	Title
03400837	BH AND NS BINARIES	Grindlay	LP	300	COMPLETE COMPACT OBJECT AND BINARY SURVEY OF 47TUC
05400594	BH AND NS BINARIES	Paerels	LP	300	High Resolution Photospheric Spectroscopy of the Neutron Star in EXO0748-676
07400594	BH AND NS BINARIES	Jonker	LP	300	The lowest-luminosity quiescent neutron star transient: implications for strong field gravity and the neutron star EoS
07400810	BH AND NS BINARIES	Miller	LP	300	CHAZSS: The Chandra HETGS Atoll/Z Spectroscopic Survey
10400425	BH AND NS BINARIES	Galloway	TOO/LP	380	Photospheric radius-expansion bursts at high spectral resolution
10400827	BH AND NS BINARIES	Homan	LP	323	The cooling neutron star in the super-Eddington accretor XTE J1701-462
12400372	BH AND NS BINARIES	Galloway	TOO/LP	350	Photospheric radius-expansion bursts at high spectral resolution
12400926	BH AND NS BINARIES	Tomsick	LP	540	Census of the Normal Spiral Arm Region
14400870	BH AND NS BINARIES	Zezas	XVP	1100	The Small Magellanic Cloud - A Case Study of X-ray Populations at Low Metallicity

Subject Category: BH AND NS BINARIES

Proposal Number: 03400837

Title: COMPLETE COMPACT OBJECT AND BINARY SURVEY OF 47TUC

Type: LP Total Time: 300

PI Name: Johnathan Grindlay

Our cycle 1 observation of 47Tuc has shown its promise as the ultimate laboratory for study of the production and evolution of compact binaries and compact objects in globular clusters. We propose a deep (4 x 75ksec) ACIS-S observation to measure the complete populations of millisecond pulsars (MSPs) and cataclysmic variables (CVs) by their variability and spectra and to constrain the main sequence binary population. Coordinated HST (ACS) data would provide unique identifications of CVs and many MSPs and allow the full population of quiescent low mass x-ray binaries to be distinguished from CVs. This dataset would provide fundamental constraints for the origins of neutron stars, millisecond pulsars, magnetic white dwarfs and compact binaries in globular clusters.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
00:24:05.80	-72:04:51.20	47 TUCANAE	ACIS-S	NONE	300

Subject Category: BH AND NS BINARIES

Proposal Number: 05400594

Title: High Resolution Photospheric Spectroscopy of the Neutron Star in EXO0748-676

Type: LP Total Time: 300

PI Name: Frits Paerels

Recently, we discovered narrow absorption features in the spectrum of 28 X-ray bursts from the neutron star in the LMXB EXO0748-676, whose properties point to a photospheric origin. The transition wavelengths are consistent with the n=2-3 lines in H- and He-like Fe, exhibiting a gravitational redshift of z=0.35. The measured line strengths indicate that the lines are significantly broadened by the Stark effect, and this will ultimately provide an opportunity to determine both the mass and the radius of this neutron star. Here we propose a very deep spectroscopic observation with Chandra HETGS, to detect the Fe Lyman spectrum and obtain crucial independent spectroscopic confirmation for the Balmer line identification, and to measure the spin period of the neutron star.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
07:48:33.30	-67:45:00.00	EXO 0748-676	ACIS-S	HETG	300

Subject Category: BH AND NS BINARIES

Proposal Number: 07400594

Title: The lowest-luminosity quiescent neutron star transient: implications for strong field gravity and the neutron star EoS

Type: LP Total Time: 300

PI Name: Peter Jonker

We propose to obtain a 300 ksec ACIS-S observation of the quiescent neutron star (NS) SXT 1H1905+000. Because of a non-detection during a previous 25 ksec Chandra ACIS-S observation, the NS quiescent luminosity is the lowest of all NS SXTs. It also has a low N_H, a well-known source distance, and an accurately known source position. These observations will eliminate the gap in the derived quiescent luminosities between NS and BH SXTs which is used as being evidence for a BH event horizon. Furthermore, this extremely low NS luminosity allows us to derive that 1H1905+000 harbors a cold, massive NS ruling out all equations of state (EoSs) except the stiffest EoSs for NSs with a nucleonic core. Constraining the NS EoS is one of the ultimate goals of NS studies.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
19:08:27.00	+00:10:08.00	1H 1905+000	ACIS-S	NONE	300

Subject Category: BH AND NS BINARIES

Proposal Number: 07400810

Title: CHAZSS: The Chandra HETGS Atoll/Z Spectroscopic Survey

Type: LP Total Time: 300

PI Name: Jon Miller

High-res. X-ray spectroscopy of accretion-powered sources in the Chandra era has focused on black holes. Neutron stars with low magnetic fields - "Z" and "atoll" binaries - have largely been ignored and/or poorly observed at high resolution. We propose a survey of 6 "Z" and "atoll" neutron star binaries. In a total of only 300 ksec, we can observe each of the 6 sources in our sample twice, obtaining consistent, robust, and constraining spectra free from photon pile-up. High-res. spectroscopy will break degeneracies in X-ray timing-based models for the accretion flows in these systems, and provide new insights into both the origin of the "kHz" QPOs seen in these sources and the nature of the "Z" and "atoll" tracks they trace in color-color diagrams.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:02:44.50	-36:25:23.00	GX 349+2	ACIS-S	HETG	50
18:16:01.40	-14:02:11.00	GX 17+2	ACIS-S	HETG	50
16:45:47.70	-45:36:40.00	GX 340+0	ACIS-S	HETG	50
18:23:40.50	-30:21:40.00	4U 1820-30	ACIS-S	HETG	50
16:40:55.50	-53:45:05.00	4U 1636-53	ACIS-S	HETG	50
17:38:58.30	-44:27:00.00	4U 1735-44	ACIS-S	HETG	50

Subject Category: BH AND NS BINARIES

Proposal Number: 10400425

Title: Photospheric radius-expansion bursts at high spectral resolution

Type: TOO/LP Total Time: 380

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:31:57.40	-33:50:05.00	4U 1728-34	ACIS-S	HETG	250
17:38:58.30	-44:27:00.00	4U 1735-44	ACIS-S	HETG	130

Subject Category: BH AND NS BINARIES

Proposal Number: 10400827

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

Type: LP Total Time: 323

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.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	38
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	49
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	62
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	76
17:00:58.50	-46:11:08.60	XTE J1701-462	ACIS-S	NONE	98

Subject Category: BH AND NS BINARIES

Proposal Number: 12400372

Title: Photospheric radius-expansion bursts at high spectral resolution

Type: TOO/LP Total Time: 350

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, and these predictions have been corroborated recently in low-resolution RXTE spectra. We propose to search for such features in bursts from sources known for frequent radius-expansion bursts. This resubmission of an untriggered AO-10 proposal will result in detection of up to 30 bursts, also allowing detailed comparisons of recurrence time and energetics with numerical ignition models, as well as a high signal-to-noise persistent spectrum. Detection of discrete features from the burst spectra may lead to constraints on the compactness and hence the neutron-star equation of state.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:38:58.30	-44:27:00.00	4U 1735-44	ACIS-S	HETG	150

Subject Category: BH AND NS BINARIES

Proposal Number: 12400926

Title: Census of the Normal Spiral Arm Region

Type: LP Total Time: 540

PI Name: John Tomsick

Despite having only moderate hard X-ray sensitivity, the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) has greatly expanded our knowledge of High-Mass X-ray Binaries (HMXBs) by finding large numbers and new types of HMXBs. There are good reasons to think that even fainter HMXBs should be present, and we propose to use Chandra to survey part of the Norma region, which is the location with the highest density of HMXBs. This will be important for understanding the HMXB population and its evolution, the HMXB luminosity function and how faint wind-accrting HMXBs can be, as well as providing critical estimates for Advanced-LIGO source rates. IR follow-up is proposed, and the subarcsecond Chandra positions are critical.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
16:37:27.30	-47:07:36.80	Norma Region	ACIS-I	NONE	540

Subject Category: BH AND NS BINARIES

Proposal Number: 14400870

Title: The Small Magellanic Cloud - A Case Study of X-ray Populations at Low Metallicity

Type: XVP Total Time: 1100

PI Name: Andreas Zezas

We propose a deep survey of 11 fields (100 ks each) in the SMC probing young (10-100 Myr) stellar populations of different ages down to a luminosity limit of 2E32 erg/s, well into the regime of quiescent X-ray binaries and X-ray emitting normal stars. These observations will provide the deepest luminosity functions (XLFs) of X-ray binaries ever recorded, enabling us to: (a) directly measure their formation efficiency as a function of age; (b) address the evolution of their XLF in the 10-100Myr range, (c) constrain the duty cycles of accreting pulsars; and (d) constrain parameters relevant to their formation and evolution. We will also observe for the first time low (0.2Zo) metallicity stars, and we will search for central compact objects in SNRs, and characterize their SN type.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
01:11:10.10	-72:44:03.50	SMC Deep Field 01	ACIS-I	NONE	100
01:13:33.20	-72:32:41.80	Deep Field 02	ACIS-I	NONE	100
01:13:56.90	-73:20:34.00	Deep Field 03	ACIS-I	NONE	100
01:13:39.90	-73:08:37.20	Deep Field 04	ACIS-I	NONE	100
00:56:08.60	-72:35:02.50	Deep Field 05	ACIS-I	NONE	100
00:52:46.60	-72:42:11.80	Deep Field 06	ACIS-I	NONE	100
00:51:52.00	-73:00:24.60	Deep Field 07	ACIS-I	NONE	100
00:49:43.20	-72:49:16.30	Deep Field 09	ACIS-I	NONE	100
00:41:00.00	-73:19:60.00	Deep Field 10	ACIS-I	NONE	100
00:47:09.60	-73:07:33.00	Deep Field 11	ACIS-I	NONE	100
00:56:35.90	-72:20:06.30	Deep Field 08	ACIS-I	NONE	100

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