Accepted Cycle 11 Observing Proposals

GALACTIC DIFFUSE EMISSION & SURVEYS

Proposal Number	Subject Category	PI Name	Title
11910040	GALACTIC DIFFUSE EMISSION AND SURVEYS	Murray	GTO ChIcAGO: Chandra Identification of ASCA Galactic Objects
11910605	GALACTIC DIFFUSE EMISSION AND SURVEYS	Bower	X-Ray Counterparts to Radio Transients
11910648	GALACTIC DIFFUSE EMISSION AND SURVEYS	Fang	Probing Galactic Feedback with X-ray Binaries
11910849	GALACTIC DIFFUSE EMISSION AND SURVEYS	Terrier	Sgr B2 ten year later: on the nature of the hard X-rays from the CMZ

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 11910040

Title: GTO ChIcAGO: Chandra Identification of ASCA Galactic Objects

PI Name: Steve Murray

X-ray sources in the Galactic plane trace a variety of exotic populations. Most sources with X-ray fluxes above 1e-11 erg/cm^2/s are well-known objects, while below 1e-13 erg/cm^2/s, AGN, CVs, and active stars dominate. However, many low-latitude sources lie between these two regimes, corresponding to young populations of pulsars, magnetars, hot stars and supernova remnants. To derive the birth-rates, lifetimes and distributions of these relatively rare sources, we propose to localize the unidentified objects in the 60% of the Galactic disk covered by the ASCA Galactic Plane Survey. Combined with archival analyses, multi-wavelength follow-up and the results of previous surveys, this will complete the demography of Galactic X-ray sources, from Sco X-1 down to the faintest sources known.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
14:57:33.00	-59:01:18.00	AX J145732-5901	ACIS-S	NONE	10
15:10:06.00	-58:24:54.00	AX J151005-5824	ACIS-S	NONE	10
16:59:05.70	-42:07:27.20	AX J165901-4208	ACIS-S	NONE	10
18:24:38.10	-13:10:47.00	AX J182435-1311	ACIS-S	NONE	10
18:33:56.40	-08:22:18.60	AX J183356-0822	ACIS-S	NONE	10

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 11910605

Title: X-Ray Counterparts to Radio Transients

PI Name: Geoffrey Bower

The radio transient sky is poorly known. We have recently conducted the most sensitive survey for radio transients (RTs) that has discovered 10 RTs, which have a duration of less than one week, a flaring amplitude of greater than 100, and no identification in deep radio and optical images. These RTs have no clear association with known phenomena. Possible X-ray counterparts to the RTs include isolated neutron stars, active stars, and optically-obscured AGN. An origin with any of these source classes requires a new understanding of event rates and luminosity functions. We propose Chandra ACIS-I observations of this field. Discovery of X-ray counterparts will have a significant impact on our understanding of the processes at work and possibly identify a new source class.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
15:02:20.50	+78:16:14.90	CAMPBE	ACIS-I	NONE	50

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 11910648

Title: Probing Galactic Feedback with X-ray Binaries

PI Name: Taotao Fang

Recent X-ray observations of the Galactic X-ray binaries revealed a number of narrow absorption lines produced by metals in the hot gas; however, it is unclear whether this hot gas is intrinsic to the source, or in the hot interstellar medium, and the answer to this question has fundamental implication in probing Galactic feedback processes. We propose one ToO observation to study X-ray bright sources spatially close to these X-ray binaries. We expect that the hot gas would produce similar absorption if it is ISM in origin. Due to the different intrinsic properties and environment of these X-ray binaries, our observations will offer a clean test of the nature of the hot gas.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
18:35:44.10	-32:59:29.00	XB 1832-330	ACIS-S	LETG	100
17:08:54.40	-32:18:57.50	4U 1705-32	ACIS-S	LETG	100

Subject Category: GALACTIC DIFFUSE EMISSION AND SURVEYS

Proposal Number: 11910849

Title: Sgr B2 ten year later: on the nature of the hard X-rays from the CMZ

PI Name: Regis Terrier

The origin of the GC molecular clouds 6.4 keV emission has long been a matter of controversy: irradiation by cosmic ray electrons or by X-rays emitted by a flaring source. An interesting candidate in the latter case is a possible 300 yr old flare of Sgr A* of 6 order of magnitude above its current quiescent level. Using 6 years of monitoring of the GC we show a lightcurve of Sgr B2 revealing a significant decrease of the hard X-ray flux with a 20-year timescale, favoring the second scenario. We propose a deep Chandra exposure of Sgr B2 to search for the morphological changes in the cloud emission compared with a similar exposure taken in March 2000. This variations pattern is a key element to finally settle the controversy and understand the actual origin of the likely irradiating source.

R.A.	Dec.	Target Name	Det.	Grating	Exp.Time
17:47:24.30	-28:24:37.10	Sgr B2	ACIS-I	NONE	100

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