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J/ApJ/643/356       Transient X-ray sources in M31           (Williams+, 2006)

A catalog of transient X-ray sources in M31. Williams B.F., Naik S., Garcia M.R., Callanan P.J. <Astrophys. J., 643, 356-375 (2006)> =2006ApJ...643..356W
ADC_Keywords: Galaxies, nearby ; X-ray sources Keywords: accretion, accretion disks - binaries: close - galaxies: individual (M31) - X-rays: binaries - X-rays: stars Abstract: From 1999 October to 2002 August, 45 transient X-ray sources were detected in M31 by Chandra and XMM-Newton. We have performed spectral analysis of all XMM-Newton and Chandra ACIS detections of these sources, as well as flux measurements of Chandra HRC detections. The result is absorption-corrected X-ray light curves for these sources covering this 2.8yr period, along with spectral parameters for several epochs of the outbursts of most of the transient sources. We supply a catalog of the locations, outburst dates, peak observed luminosities, decay time estimates, and spectral properties of the transient sources, and we discuss similarities with Galactic X-ray novae. Duty cycle estimates are possible for eight of the transients and range from 34% to 2%; upper limits to the duty cycles are estimated for an additional 15 transients and cover a similar range. We find five transients that have rapid decay times and may be ultracompact X-ray binaries. Spectra of three of the transients suggest that they may be faint Galactic foreground sources. If even one is a foreground source, this suggests a surface density of faint transient X-ray sources of ≳1deg2. Description: We obtained archival Chandra HRC and ACIS data of M31 with sampling every few months from 1999 October to 2002 August. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 38 45 Transient catalog table2.dat 160 195 Spectral Fits to Transient Detections
See also: B/chandra : The Chandra Archive Log (CXC, 2002) J/ApJ/577/738 : M31 Chandra X-ray point sources (Kong+, 2002) J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002) J/ApJ/609/735 : M31 Chandra X-ray sources (Williams+, 2004) J/ApJ/610/247 : M31 supersoft and quasi-soft X-ray sources (Di Stefano+, 2004) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 A6 --- [KGP2002] Source identification (origin in Kong et al. 2002ApJ...577..738K, Cat. J/ApJ/577/738) 9- 10 I2 h RAh Riight ascension (J2000.0) 12- 13 I2 min RAm Right ascension (J2000.0) 15- 19 F5.2 s RAs Right ascension (J2000.0) 21 A1 --- DE- Declination sign (J2000.0) 22- 23 I2 deg DEd Declination (J2000.0) 25- 26 I2 arcmin DEm Declination (J2000.0) 28- 32 F5.2 arcsec DEs Declination (J2000.0) 34- 38 A5 --- Ref Detection references (1)
Note (1): References as follows: 1 = Di Stefano et al., 2004ApJ...610..247D, Cat. J/ApJ/610/247 2 = Garcia et al., 2001ATel...79....1G 3 = Kong et al., 2001ATel...76....1K 4 = Kong et al., 2002ApJ...577..738K, Cat. J/ApJ/577/738 5 = Kong et al., 2002ATel...97....1K 6 = New 7 = Osborne et al., 2001A&A...378..800O 8 = Shirey, 2001IAUC.7659....1S 9 = Trinchieri & Fabbiano, 1991ApJ...382...82T 10 = Trudolyubov et al., 2001ApJ...563L.119T 11 = Trudolyubov et al., 2002IAUC.7798....2T 12 = Williams et al., 2004ApJ...609..735W, Cat. J/ApJ/609/735
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 6 A6 --- [KGP2002] Source identification 8- 17 A10 "DD/MM/YYYY" Obs.Date Date of Observation 19- 24 A6 --- Inst Telescope/Instrument used 26- 35 I10 --- OBSID Observational identification code 37- 41 I5 ct Ct1 ? Net counts in detection (1) 43- 46 I4 ct Ct2 ? XMM MOS1 net counts in detection 48- 51 I4 ct Ct3 ? XMM MOS2 net counts in detection 53- 55 A3 --- Model Model used to fit spectrum (2) 57- 61 F5.2 10-21cm-2 NH ? Hydrogen column density 63- 66 F4.2 10-21cm-2 E_NH ? Upper uncertainty limit in NH 68- 71 F4.2 10-21cm-2 e_NH ? Uncertainty (or lower limit) in NH 73- 75 F3.1 --- Gamma ? Best fit power law slope 77- 79 F3.1 --- E_Gamma ? Upper uncertainty limit in Gamma 81- 83 F3.1 --- e_Gamma ? Uncertainty (or lower limit) in Gamma 85- 89 F5.3 --- T ? Temperature parameter (3) 91- 95 F5.3 --- E_T ? Upper uncertainty limit in T 97-101 F5.3 --- e_T ? Uncertainty (or lower limit) in T 103-109 F7.3 --- chi2 ? Model χ2 value 111-113 I3 --- DoF ? Degrees of freedom 115-119 F5.3 --- Prob ? Probability of fit (4) 121-125 F5.2 --- HR1 ? First hardness ratio, M-S/M+S (5) 127-130 F4.2 --- e_HR1 ? Uncertainty in HR1 132-136 F5.2 --- HR2 ? Second hardness ratio, H-S/H+S (6) 138-141 F4.2 --- e_HR2 ? Uncertainty in HR2 143-148 F6.1 10+29W LX Absorption-corrected X-ray luminosity in units of 1036 erg/s (7) 150-154 F5.1 10+29W E_LX ? Upper uncertainty limit in LX 156-160 F5.1 10+29W e_LX Uncertainty (or lower limit) in LX
Note (1): If an XMM observation then this is from the PN instrument. Note (2): Model used to fit spectrum as follows: pl = power-law bb = blackbody pb = power-law plus blackbody dbb = disk blackbody pdb = power-law plus disk blackbody nsa = neutron star atmosphere Note (3): For the bb or pb models, this number is kT in keV. For the dbb model this value is kT in keV of the inner edge of the accretion disk. For the nsa model this value is log(Teff) for the atmosphere of the neutron star. Note (4): The probability that this fit is representative of the true spectrum, determined from chi/DoF. Note (5): Calculated by taking the ratio of M-S/M+S, where S is the number of counts from 0.3-1keV and M is the number of counts from 1-2keV. Note (6): Calculated by taking the ratio of H-S/H+S, where S is the number of counts from 0.3-1keV and H is the number of counts from 2-7keV. Note (7): Assuming a distance of 780kpc.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 26-Sep-2008
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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