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 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:
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FileName Lrecl Records Explanations
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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
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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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
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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- 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
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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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
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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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
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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