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J/ApJ/664/458       Spectral fit of ULX sources                  (Devi+, 2007)

The dependence of the estimated luminosities of ultraluminous X-ray sources on spectral models. Devi A.S., Misra R., Agrawal V.K., Singh K.Y. <Astrophys. J., 664, 458-466 (2007)> =2007ApJ...664..458D
ADC_Keywords: Galaxies, nearby ; X-ray sources ; Models Keywords: galaxies: general - X-rays: binaries Abstract: Data from Chandra observations of 30 nearby galaxies were analyzed and 365 X-ray point sources were chosen whose spectra were not contaminated by excessive diffuse emission and not affected by photon pileup. The spectra of these sources were fitted using two spectral models (an absorbed power-law and a disk blackbody) to ascertain the dependence of estimated parameters on the spectral model used. It was found that the cumulative luminosity function depends on the choice of the spectral model, especially for luminosities >1040ergs/s. A large number (∼80) of the sources have luminosities >1039ergs/s (ultraluminous X-ray sources) with indistinguishable average spectral parameters (inner disk temperature ∼1keV and/or photon index GAMMA∼2) with those of the lower luminosity ones. Description: The names of the 30 host galaxies and the details of the Chandra ACIS observations are tabulated in Table 1. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 36 30 Sample galaxy properties table2.dat 43 15 List of sources with count rate > 0.05counts/s table3.dat 89 365 Spectral properties of point sources fitted with the power-law model table4.dat 90 365 Spectral properties of point sources fitted with the disk black body model
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Galaxy Galaxy name 9 A1 --- --- [/] 10- 17 A8 --- Gal2 Associated galaxy 19- 22 F4.1 Mpc Dist Distance 24- 27 I4 --- ObsID Chandra observation ID 29- 33 F5.2 ks Texp Exposure time 35- 36 I2 --- N Number of point sources with total counts from the source ≥60, as detected by wavdetect with fluxscale=1
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Galaxy Galaxy name 10- 11 I2 h RAh Right ascension (J2000) 13- 14 I2 min RAm Right ascension (J2000) 16- 20 F5.2 s RAs Right ascension (J2000) 22 A1 --- DE- Declination sign (J2000) 23- 24 I2 deg DEd Declination (J2000) 26- 27 I2 arcmin DEm Declination (J2000) 29- 33 F5.2 arcsec DEs Declination (J2000) 35- 43 F9.7 ct/s CR Count rate
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Galaxy Galaxy name 10- 11 I2 h RAh Hour of Right Ascension (J2000) 13- 14 I2 min RAm Minute of Right Ascension (J2000) 16- 20 F5.2 s RAs Second of Right Ascension (J2000) 22 A1 --- DE- Sign of the Declination (J2000) 23- 24 I2 deg DEd Degree of Declination (J2000) 26- 27 I2 arcmin DEm Arcminute of Declination (J2000) 29- 33 F5.2 arcsec DEs Arcsecond of Declination (J2000) 35- 38 F4.2 10+22cm-2 nHpl Equivalent H column density (power-law) 40- 43 F4.2 10+22cm-2 E_nHpl Upper limit uncertainty in nHpl 45- 48 F4.2 10+22cm-2 e_nHpl Lower limit uncertainty in nHpl 50- 53 F4.2 --- Gamma Photon power-law index 55- 58 F4.2 --- E_Gamma Upper limit uncertainty in Gamma 60- 63 F4.2 --- e_Gamma Lower limit uncertainty in Gamma 65- 69 F5.2 [10-7W] logLpl 0.3-8keV luminosity in erg/s (power-law) 71- 74 F4.2 [10-7W] E_logLpl Upper limit uncertainty in logLpl 76- 79 F4.2 [10-7W] e_logLpl Lower limit uncertainty in logLpl 81- 86 F6.2 --- Cst.pl C-statistic result in power-law model (G1) 88- 89 I2 --- dof.pl Degree of freedom in power-law
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Galaxy Galaxy name 10- 11 I2 h RAh Hour of Right Ascension (J2000) 13- 14 I2 min RAm Minute of Right Ascension (J2000) 16- 20 F5.2 s RAs Second of Right Ascension (J2000) 22 A1 --- DE- Sign of the Declination (J2000) 23- 24 I2 deg DEd Degree of Declination (J2000) 26- 27 I2 arcmin DEm Arcminute of Declination (J2000) 29- 33 F5.2 arcsec DEs Arcsecond of Declination (J2000) 35- 38 F4.2 10+22cm-2 nHbb Equivalent H column density (blackbody) 40- 43 F4.2 10+22cm-2 E_nHbb Upper limit uncertainty in nHbb 45- 48 F4.2 10+22cm-2 e_nHbb Lower limit uncertainty in nHbb 50- 54 F5.2 keV kT Inner disk temperature 56- 59 F4.2 keV E_kT Upper limit uncertainty in kT 61- 64 F4.2 keV e_kT Lower limit uncertainty in kT 66- 70 F5.2 [10-7W] logLbb Bolometric X-ray luminosity erg/s (blackbody) 72- 75 F4.2 [10-7W] E_logLbb Upper limit uncertainty in logL 77- 80 F4.2 [10-7W] e_logLbb Lower limit uncertainty in logL 82- 87 F6.2 --- Cst.bb C-statistic result in blackbody model (G1) 89- 90 I2 --- dof.bb Degree of freedom in blackbody model
Global Notes: Note (G1): a better fit is significant when the difference between C-statistics is larger than 2.7. As a result, the disk blackbody model shows a better fit for 23 sources, the power-law lodem for 67 sources; 275 sources have equivalent fits for both laws.
Nomenclature note: Sources identified as [DMA2007] JHHMMSS.ss+DDMMSS.ss in Simbad History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 22-Aug-2009
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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