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M31CXO2 - M 31 Bulge Chandra X-Ray Point Source Catalog

HEASARC
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Overview

The authors explore the population of X-ray point sources in the bulge of M 31 so as to contrast properties of various subpopulations, such as persistent and transient sources and primordial LMXBs and dynamically formed ones. Based on the data from 26 archival Chandra ACIS observations with aimpoints within 10 arcminutes of the center of M 31 (J2000 coordinates of 00:42:44.31, +41:16:09.4), the authors study the source content and properties of various subpopulations of X-ray sources to a maximum distance of 12 arcminutes from the centre of M 31.

To a limiting luminosity of ~1035 erg s-1, the authors find 263 X-ray point sources, with ~1/3 of these being background galaxies. A study of the spatial distribution and the luminosity function of the X-ray sources shows that the distribution of primordial LMXBs is consistent with the distribution of the K-band light and that their luminosity function flattens below ~1037 erg s-1 to the dN/dL ~ L-1 law in agreement with the behaviour found earlier for LMXBs in the Milky Way and in Cen A. Within a radius of 12 arcminutes, the luminosity function is independent of distance to the centre of M 31, in contrast to earlier Chandra studies. The LMXBs located in globular clusters and within ~1 arcminute from the centre of M 31 are presumably created via dynamical interactions. The dynamical origin of the r < 1 arcminute sources is strongly suggested by their radial distribution which follows the rho_*2 profile rather than the K-band light distribution. Their luminosity function shows a prominent fall-off below log(L_X) <~ 36.5. Although the statistics are insufficient to claim a genuine low-luminosity cut-off in the luminosity function, the best fit powerlaw with a slope of -0.6 +/- 0.2 is significantly flatter than the dN/dL ~ L-1 law. The authors also searched for transients and found 28 sources that varied by a factor larger than 20. Their spatial distribution follows the distribution of the persistent LMXBs within the accuracy allowed by the limited number of transients.


Catalog Bibcode

2007A&A...468...49V

References

A study of the population of LMXBs in the bulge of M31.
    Voss R., Gilfanov M.
   <Astron. Astrophys., 468, 49-59 (2007)>
   =2007A&A...468...49V

Provenance

This HEASARC table was created in March 2010 based on CDS catalog J/A+A/468/49 file table2.dat.

Parameters

Source_Number
A sequential identification number for the X-ray source which uniquely identifies each source in the catalog, in order of increasing angular offset from the center of M 31.

Name
The X-ray source designation using the '[VG2007]' prefix (for Voss and Gilfanov 2007) and the source number, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000 coordinates and to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 coordinates and to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Center_Offset
The angular distance of the X-ray source from the center of M 31 (J2000 coordinates of 00:42:44.31, +41:16:09.4), in arcseconds.

Raw_Counts
The number of counts C in the source region in the energy range 0.5 - 8 keV before correction for PSF, background and confusing sources.

Counts
The X-ray source counts S calculated according to equation (1) of the reference paper, including correction for PSF, background and confusing sources.

Counts_Error
The statistical error in the X-ray source counts S calculated according to equation (2) of the reference paper.

Lx
The X-ray luminosity of the source in the energy range 0.5 - 8 keV, in erg s-1, calculated assuming the source is at the 780 kpc distance of M 31.

Broad_Type
A broad source classification, using the following abbreviations:

    GC    = confirmed globular cluster
    GCC   = globular cluster candidate
    PN    = planetary nebula
    FGS   = foreground star
    Nova  = nova
    Rnova = nova (random match)
    EmO   = emission line object
    RAD   = radio source
    SNR   = supernova remnant
    EXT   = extended source
    t     = transient source
  

Alt_Name_1
A precise source identification and references thereof, using the following abbreviations:

      B68 = Borngen (1968AN....291...19BA), [B68] NN in Simbad
      B90 = Braun (1990ApJS...72..761B), [B90] NNN in Simbad
      Bol = Galleti et al. (2004, Cat. <J/A+A/416/917>), Bol NNN in Simbad
      CFN = Ciardullo et al. (1987ApJ...318..520C, [CFN87] NN in Simbad
      CIA = Ciardullo et al. (1989, Cat. <J/ApJ/339/53>), Ford M 31 NNN
      Cra = Crampton et al. (1984ApJ...284..663C), C84 NNN in Simbad
      Fan = Fan et al. (2005PASP..117.1236F), [FMZ2005] NN in Simbad
      GLG = Gelfand et al. (2004, Cat. <J/ApJS/155/89>), GLG NNN
      MG  = Magnier et al. (1995, Cat. <J/A+AS/114/215>), [MPV95] B-NNN in Simbad
      MLA = Meyssonnier et al. (1993, Cat. <J/A+AS/102/251>), MLA NNNN in Simbad
     Mita = Magnier, 1993, Ph.D. Thesis, MIT
      PIE = Pietsch et al. (2005A&A...442..879P), [PFF2005] WeCAPP-NYYYY-NN
      SI  = Shafter & Irby (2001ApJ...563..749S), [SI2001] 1997-06 in Simbad)
      SIM = Simbad, WSTB 37W135 in Simbad
      W2  = Williams et al. (2004AJ....128.1588W)
  

Alt_Name_2
The source designation in Kong et al. (2002, Cat. J/ApJ/577/738), Williams et al. (2004, Cat. J/ApJ/609/735), and/or Williams et al. (2004AJ....128.1588W).

Source_Flag
Sources not included in Kong et al. (2002, Cat. J/ApJ/577/738), Williams et al. (2004, Cat. J/ApJ/609/735), and/or Williams et al. (2004AJ....128.1588W) are indicated by 'K' if observed in Kaaret (2002, Cat. <J/ApJ/578/114>), else by 'X' to indicate that that these are new sources.

Class
The HEASARC Browse object classification, based on the broad_type parameter value when available.


Contact Person

Questions regarding the M31CXO2 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 24-Mar-2010