J/ApJ/706/223 X-ray point sources near the Galactic Center (Hong+, 2009)
Radial distribution of X-ray point sources near the Galactic Center.
Hong J., van den Berg M., Grindlay J.E., Laycock S.
<Astrophys. J., 706, 223-237 (2009)>
=2009ApJ...706..223H 2009ApJ...706..223H
ADC_Keywords: X-ray sources ; Surveys
Keywords: Galaxy: bulge - Galaxy: center - stars: statistics -
X-rays: binaries - X-rays: stars
Abstract:
We present the log N-logS and spatial distributions of X-ray point
sources in seven Galactic bulge (GB) fields within 4° from the
Galactic center (GC). We compare the properties of 1159 X-ray point
sources discovered in our deep (100ks) Chandra observations of three
low extinction Window fields near the GC with the X-ray sources in the
other GB fields centered around Sgr B2, Sgr C, the Arches Cluster, and
Sgr A* using Chandra archival data. To reduce the systematic errors
induced by the uncertain X-ray spectra of the sources coupled with
field-and-distance-dependent extinction, we classify the X-ray sources
using quantile analysis and estimate their fluxes accordingly. We also
compare the total X-ray and infrared surface brightness using the
Chandra and Spitzer observations of the regions. GB X-ray sources can
be of the same or similar type. Their X-ray luminosity and spectral
properties support the idea that the most likely candidate is magnetic
cataclysmic variables (CVs), primarily intermediate polars (IPs).
Description:
We performed Chandra/ACIS-I observations of the Baade's Window (BW)
field on 2003 July 9, the Stanek's Window (SW) field on 2004 February
14/15, and the "Limiting Window" (LW) field on 2005 August 19/22 and
October 25. Table 1 summarizes the observational parameters and X-ray
source statistics of the Window and Galactic bulge (GB) fields.
This work is part of our Chandra Multi-wavelength Plane (ChaMPlane)
Survey designed to measure the space density and probable nature of
the low-luminosity accretion-powered sources in the Galaxy (Grindlay
et al. 2005ApJ...635..907H 2005ApJ...635..907H).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 8 Selected Galactic Bulge (GB) fields
table2.dat 258 5771 Catalog of X-ray point sources in the Window and
four Galactic bulge (GB) fields
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
J/ApJS/194/18 : The Galactic Bulge Survey: X-ray observations (Jonker+, 2011)
J/ApJ/700/1702 : ChaMPlane deep galactic bulge survey. I. (van den Berg+, 2009)
J/ApJ/703/30 : NIR counterparts to Chandra X-ray sources. I. (Mauerhan+,
2009)
J/ApJ/685/463 : ChaMPlane X-ray sources in the Galactic bulge (Koenig+, 2008)
J/ApJ/685/958 : Spitzer and Chandra sources in galactic center (Arendt+ 2008)
J/MNRAS/371/38 : X-ray observations of the Galaxy center (Wang+, 2006)
J/ApJ/613/1179 : X-ray sources in Galactic Center (Muno+, 2004)
J/ApJ/589/225 : Chandra X-ray sources toward Galactic Center (Feigelson+,
2003)
http://hea-www.harvard.edu/ChaMPlane/ : ChaMPlane home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Field Field name
15 A1 --- n_Field [e] stacked pointings (1)
17- 32 A16 --- ObsID Chandra obsID
34- 38 F5.2 deg GLON ? Galactic longitude in decimal degrees
40- 44 F5.2 deg GLAT ? Galactic latitude in decimal degrees
46- 49 F4.2 deg Offset ? Aim point offset from Sgr A*
51- 55 F5.2 10+22cm-2 N(H) ? Neutral hydrogen column density (2)
57- 59 I3 ks GTI The good time intervals (GTIs) (3)
61- 64 I4 --- BxCt Number of sources with net count≥1 in
band 0.3-8keV (4)
66- 68 I3 --- SxCt Number of sources with net count≥1
in band 0.3-2.5keV (4)
70- 73 I4 --- Hxct Number of sources with net count≥1 in
band 2.5-8keV (4)
75- 78 I4 --- Comb Combined unique source count (4)
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Note (1):
e = Fourteen pointings are stacked, and they are Obs. ID 242, 2951, 2952,
2953, 2954, 2943, 3663, 3392, 3393, 3549, 3665, 4683, 4684, and 5360.
Note (2): The estimates for the integrated neutral hydrogen column density along
the line of the sight by Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S) for the
location of the aim point. This is only for guiding purpose due to the
large uncertainty in the Galactic plane fields.
Note (3): The total exposure (i.e., before cleaning) is 100ks each (750ks for
the stacked Sgr A* field).
Note (4): The number of the sources with net count ≥1 in the broad band
(0.3-8keV) on the ACIS-I CCDs (0, 1, 2, and 3) in the three detection
bands (BX: 0.3-8keV, SX: 0.3-2.5keV, HX: 2.5-8keV) and the
combined unique source list.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [CXOPS]
6- 21 A16 --- CXOPS Source Name (JHHMMSS.s+DDMMSS)
23- 35 A13 --- Field Field Name (see table 1)
37- 46 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
48- 57 F10.6 deg DEdeg Declination in decimal degrees (J2000)
59- 68 F10.7 arcsec ePos Positional Error (95%)
70- 80 F11.8 arcmin Offset Offset from the aimpoint
82- 94 F13.6 ct netBx Net counts in the 0.3-8.0keV (full) band
96-105 F10.6 ct e_netBx Statistical error in netBX
107-120 F14.9 ct netSc Net counts in the 0.5-2.0keV (soft) band
122-130 F9.6 ct e_netSc Statistical error in netSc
132-146 F15.8 ct netHc Net counts in the 2.0-8.0keV (hard) band
148-157 F10.6 ct e_netHc Statistical error in netHc
159-171 F13.9 --- SNRHc Signal-to-Noise in the 2.0-8.0keV band
173-181 F9.7 keV E50 Median energy
183-194 F12.9 keV e_E50 Error in E50
196-205 F10.8 --- QDy y-value of the Quantile Diagram (1)
207-217 F11.9 --- e_QDy Negative error of QDy
219-229 F11.9 --- E_QDy Positve error of QDy
231 I1 --- Gx [1,3] X-ray group ID (soft, medium, hard) (2)
233-245 E13.6 mW/m2 uFHc unabsorbed flux in the 2.0-8.0keV band
247-258 E12.6 mW/m2 e_uFHc Error in uFHc
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Note (1): y-value of the quantile diagram: (E25-0.3keV)/(E75-0.3keV).
Note (2): The quantile diagrams were divided into three groups: G1 (soft), G2
(medium) and G3 (hard). See figure 2 in section 3.1.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 09-Dec-2011