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J/ApJ/687/471   Observational comparison between ULXs and XRBs  (Berghea+, 2008)

Testing the paradigm that ultraluminous X-ray sources as a class represent accreting intermediate-mass black holes. Berghea C.T., Weaver K.A., Colbert E.J.M., Roberts T.P. <Astrophys. J., 687, 471-487 (2008)> =2008ApJ...687..471B
ADC_Keywords: Galaxies, nearby ; X-ray sources ; Cross identifications Keywords: accretion, accretion disks - galaxies: general - surveys - X-rays: binaries Abstract: To test the idea that ultraluminous X-ray sources (ULXs) in external galaxies represent a class of accreting intermediate-mass black holes (IMBHs), we have undertaken a program to identify ULXs and a lower luminosity X-ray comparison sample with the highest quality data in the Chandra archive. We establish as a general property of ULXs that the most X-ray-luminous objects possess the flattest X-ray spectra (in the Chandra bandpass). No prior sample studies have established the general hardening of ULX spectra with luminosity. This hardening occurs at the highest luminosities (absorbed luminosity ≥5x1039erg/s) and is in line with recent models arguing that ULXs are actually stellar mass black holes. From spectral modeling, we show that the evidence originally taken to mean that ULXs are IMBHs - i.e., the "simple IMBH model" - is nowhere near as compelling when a large sample of ULXs is looked at properly. During the last couple of years, XMM-Newton spectroscopy of ULXs has to a large extent begun to negate the simple IMBH model based on fewer objects. We confirm and expand these results, which validates the XMM-Newton work in a broader sense with independent X-ray data. Description: Our sample is derived from the list of X-ray point sources generated by the XASSIST ( Chandra pipeline. For manageability, we have chosen all Chandra ACIS sources in the public archives as of a cutoff date of 2004 October 18. A total of 69 unique objects in 89 data sets comprise our final sample. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 165 89 Properties of sample objects refs.dat 45 68 References
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) VII/145 : Nearby Galaxies Catalogue (NBG) (Tully 1988) J/ApJ/664/458 : Spectral fit of ULX sources (Devi+, 2007) J/ApJ/649/730 : ULX population in nearby galaxies from XMM (Winter+, 2006) J/A+A/429/1125 : Catalog of Ultraluminous X-ray sources (Liu+, 2005) J/ApJS/154/519 : Properties of ultraluminous X-ray candidates (Swartz+, 2004) J/MNRAS/344/134 : Chandra ultraluminous X-ray sources (Humphrey+, 2003) J/ApJS/143/25 : Intermediate-luminosity X-ray objects catalog (Colbert+, 2002) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 A2 --- S [S /SC] S for ULX sample or SC for comparison sample 4- 5 I2 --- Seq Running sequence number (<[BWC2008] {S|SC} NN> in Simbad) 7- 9 A3 --- Name Object name (<[BWC2008] {U|CNN}> in Simbad) 11 A1 --- --- [X] 12- 13 I2 h RAh X-ray hour of right ascension (J2000) 14- 15 I2 min RAm X-ray Minute of right ascension (J2000) 16- 19 F4.1 s RAs X-ray Second of right ascension (J2000) 20 A1 --- DE- Declination sign (J2000) 21- 22 I2 deg DEd X-ray degree of declination (J2000) 23- 24 I2 arcmin DEm X-ray arcminute of declination (J2000) 25- 26 I2 arcsec DEs X-ray arcsecond of declination (J2000) 28- 40 A13 --- Galaxy Host galaxy name 42- 45 F4.1 Mpc Dist ? Galaxy distance from Tully (1988, Cat. VII/145) 47- 51 F5.2 10+20/cm2 NHgal Galactic Hydrogen absorption column density 53- 56 I4 --- ObsID Observation ID 58- 63 A6 --- CCD CCD number where the object is located and subarray values (in parentheses) (1) 65- 69 F5.2 [10-7W] logLx Approximate observed luminosity in the energy band 0.3-8.0keV (2) 71- 80 A10 "YYYY/MM/DD" Date Date of observation start 82- 85 F4.1 ks Exp Exposure time 87- 94 F8.1 ct Cts Net counts in the 0.3-8.0keV energy band 96-100 F5.1 arcmin theta Off-axis angle of the source (3) 102-105 F4.1 arcmin e_Theta Theta uncertainty 107-135 A29 --- OName X-ray common names from the literature (4) 137-138 A2 --- Loc Location in the galaxy (5) 140-165 A26 --- r_OName References (see refs.dat file) (4)
Note (1): the subarray value represents the fraction of the CCD actually used in the observation. Note (2): derived from the count rate of the reprocessed data; we assumed a PL model with Γ=1.8 and a Galactic absorption column. Note (3): the values listed here and the subarray values in CCD column were used when we rejected the piled-up sources. Note (4): the names correspond to references in the same order, and references that use the same name are in parentheses; some papers do not give special names or the names are given using the coordinates, and these were not used. Note (5): Abbreviations are: A = spiral arm; D = disk; DB = disk or bulge; E = elliptical galaxy, no special location; SF = star-forming region; AM = arm in merger; N = nucleus.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Ref Reference number 4- 22 A19 --- BibCode Bibcode 24- 45 A22 --- Aut Author(s) name
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 07-Jan-2011
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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