J/ApJ/577/738 M31 Chandra X-ray point sources (Kong+, 2002)
X-ray point sources in the central region of M31 as seen by Chandra.
Kong A.K.H., Garcia M.R., Primini F.A., Murray S.S., di Stefano R.,
McClintock J.E.
<Astrophys. J. 577, 738 (2002)>
=2002ApJ...577..738K 2002ApJ...577..738K
ADC_Keywords: Galaxies, nearby ; X-ray sources
Keywords: galaxies: individual (M31) - X-rays: galaxies - X-rays: stars
Abstract:
We report on Chandra observations of the central region of M31. By
combining eight Chandra ACIS-I observations taken between 1999 and
2001, we have identified 204 X-ray sources within the central ∼17'x17'
region of M31, with a detection limit of ∼2x1035erg/s. Of these 204
sources, 22 are identified with globular clusters, two with supernova
remnants, nine with planetary nebulae, and nine with supersoft sources.
By comparing individual images, about 50% of the sources are variable
on timescales of months. We also found 13 transients, with light
curves showing a variety of shapes. We also extracted the energy
spectra of the 20 brightest sources; they can be well fitted by a
single power law with a mean photon index of 1.8. The spectral shapes
of 12 sources are shown to be variable, suggesting that they went
through state changes.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 114 204 CHANDRA ACIS catalog of the central region of M31
table4.dat 58 39 Optical IDs
table5.dat 31 77 Cross-Correlation of Chandra and ROSAT Sources
--------------------------------------------------------------------------------
See also:
B/chandra : The Chandra Archive Log (CXC, 2002)
J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002)
II/144 : Brightest stars in the field of M31 (Berkhuijsen+ 1988)
J/A+A/373/63 : M31 second ROSAT PSPC survey (Supper+, 2001)
J/A+AS/61/451 : The 37W catalogue of radio sources in M31 (Walterbos+ 1985)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- [KGP2002] Object identification
8- 13 A6 --- --- [CXOM31]
14- 29 A16 --- CXOM31 Chandra name (JHHMMSS.s+DDMMSS)
31- 32 I2 h RAh Hour of Right Ascension (J2000)
34- 35 I2 min RAm Minute of Right Ascension (J2000)
37- 42 F6.3 s RAs Second of Right Ascension (J2000)
44 A1 --- DE- Sign of the Declination (J2000)
45- 46 I2 deg DEd Degree of Declination (J2000)
48- 49 I2 arcmin DEm Arcminute of Declination (J2000)
51- 55 F5.2 arcsec DEs Arcsecond of Declination (J2000)
57- 60 F4.2 arcsec PosErr Positional error
62- 65 I4 ct NCts The net counts
67- 71 F5.2 10-2ct/s CRate The count rate in units of 10-2ct/s
73- 76 F4.2 10-2ct/s e_CRate Error in CRate
78- 82 F5.2 --- HR1 The first hardness ratio (1)
84- 87 F4.2 --- e_HR1 The error in HR1
89- 93 F5.2 --- HR2 The second hardness ratio (2)
95- 98 F4.2 --- e_HR2 The error in HR2
100-104 F5.2 10+30W LXray The 0.3-7keV luminosity in
units of 1037erg/s (3)
106-113 A8 --- Notes Additional notes (4)
--------------------------------------------------------------------------------
Note (1): HR1 = (M-S)/(M+S) where S is the 0.3-1.0keV energy band and
M is the 1-2keV energy band.
Note (2): HR2 = (H-S)/(H+S) where S is the 0.3-1.0keV energy band and
H is the 2-7keV energy band.
Note (3): Assuming an absorbed power-law model with a photon index of 1.7
and NH=1021cm-2.
Note (4): Additional notes:
e = Extragalactic objects
f = Foreground stars
g = Globular Cluster
p = Planetary nebula
r = ROSAT HRI sources
s = Supernova remnant
v = Variables
sv = Spectral variables
t = Transients
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- [KGP2002] Object identification
9- 24 A16 --- CXOM31 Chandra Name (JHHMMSS.s+DDMMSS)
26- 29 A4 ---- MType Morphological type
31- 42 A12 --- Ident Identification (1)
44- 46 F3.1 arcsec Off Radial offset between the catalogued object
and the ACIS source
48- 54 A7 --- Ident2 Second identification (1)
56- 58 F3.1 arcsec Off2 ? Radial offset between the catalogued object
and the ACIS source
--------------------------------------------------------------------------------
Note (1): Identifications as follows:
mita = Magnier, 1993, Ph.D. thesis, MIT
Bo = Battistini et al., 1987A&AS...67..447B 1987A&AS...67..447B
Ha94 = Haiman et al., 1994, Cat. II/208
Ford = Ford & Jacoby, 1978ApJ...219..437F 1978ApJ...219..437F,
Ciardullo et al., 1989ApJ...339...53
PB = Barmby, 2001, Ph.D. thesis, Harvard Univ.
DO80 = d'Odorico et al., 1980A&AS...40...67D 1980A&AS...40...67D
MLA = SIMBAD.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- [KGP2002] Object Identification
9- 24 A16 --- CXOM31 Chandra name (JHHMMSS.s+DDMMSS)
26- 27 I2 --- [PFJ93] ? ROSAT HRI Identification (Primini et al.,
1993ApJ...410..615P 1993ApJ...410..615P
29- 31 F3.1 arcsec Off Radial offset between the HRI and ACIS objects
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 06-Feb-2003