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M31XMM2 - M31 XMM-Newton Spectral Survey X-Ray Point Source Catalog

HEASARC
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Overview

This table contains the results of a complete spectral survey of the X-ray point sources detected in five XMM-Newton observations along the major axis of M 31 but avoiding the central bulge, aimed at establishing the population characteristics of X-ray sources in this galaxy.

One observation of each disc field of M 31 was taken using the EPIC pn and MOS cameras on XMM-Newton in January and June 2002. The authors obtained background-subtracted spectra and lightcurves for each of the 335 X-ray point sources detected across the five observations from 2002. They also correlate their source list with those of earlier X-ray surveys and radio, optical and infra-red catalogs. Sources with more than 50 source counts are individually spectrally fit in order to create the most accurate luminosity functions of M 31 to date.

Based on the spectral fitting of these sources with a power law model, the authors observe a broad range of best-fit photon index. From this distribution of best-fit index, they identify 16 strong high mass X-ray binary system candidates in M 31. They show the first cumulative luminosity functions created using the best-fit spectral model to each source with more than 50 source counts in the disc of M 31. The cumulative luminosity functions show a distinct flattening in the X-ray luminosity L_X interval 37.0 <~ log L_X erg s-1 <~ 37.5. Such a feature may also be present in the X-ray populations of several other galaxies, but at a much lower statistical significance. The authors investigate the number of AGN present in their source list and find that, above L_X ~1.4 x 1036 erg s-1, the observed population is statistically dominated by the point source population of M 31.


Catalog Bibcode

2009A&A...495..733S

References

An X-ray spectral survey of the disc of M31 with XMM-Newton.
    Shaw Greening L., Barnard R., Kolb U., Tonkin C., Osborne J.P.
   <Astron. Astrophys., 495, 733-741 (2009)>
   =2009A&A...495..733S

Provenance

This table was created by the HEASARC in October 2009 based on the electronic version of Table A1 from the reference paper which was obtained from the CDS (their catalog J/A+A/495/733 file tablea1.dat.

Parameters

Source_Number
A unique sequential identification number for each source in this catalog in order of increasing J2000 Right Ascension.

Alt_Name
The source designation recommended by the Dictionary of Nomenclature of Celestial Objects, using the prefix of '[SBK2009]' for Shaw Greening, Barnard, Kolb 2009 and the source number.

Name
The standard designation for an XMM-Newton X-ray source using the 'XMMU' prefix and the J2000 equatorial coordinates.

RA
The Right Ascension of the X-ray source in the selected equinox as returned by the source detection routines. (No astrometric corrections were applied). This was given in J2000 coordinates to an accuracy of 0.1 seconds of time in the original reference.

Dec
The Declination of the X-ray source in the selected equinox as returned by the source detection routines. (No astrometric corrections were applied). This was given in J2000 coordinates to an accuracy of 1 arcsecond in the original reference.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Det_Instruments
The XMM-Newton camera(s) from which the source spectra and/or counts were taken. If both pn and mos cameras were used, the X-ray luminosities derived from each are given as the parameters lx_1 and lx_2, respectively.

Spectral_Model
The best-fit x-ray spectral model. Best fit values are given for all sources with more than 50 source counts; even for cases where the fit implies significant or very large error bars. Sources with less than 50 source counts are denoted with ``faint'' as their best fit model, these sources are then summed by field and the parameters of the best-fit power law to the summed spectrum applied to each source. Hence for the faint sources no absorption or spectral index/temperature (kT) values are given.

The best-fit model types for a source can be as follows:

      faint = less than 50 source counts (no Gamma/kT value)
         pl = power law (Gamma)
         bb = blackbody (kT)
         br = bremsstrahlung (kT)
        nsa = neutron star atmosphere (kT)
     diskbb = disk blackbody (kT)
      13060 = the meaning of this value is not known to the HEASARC
  

NH_Flag
This flag parameter is set to 'f' to indicate that the column density n_H was fixed to the Galactic foreground value of 0.1 x 1022 H-atom/cm2 in the fit.

NH
The best-fit hydrogen column density, n_H, in H-atom/cm2. Note that several of the faint sources display a very large formal uncertainty in n_H. The actual best-fit values were accepted only if they exceeded the Galactic foreground value of 0.1 x 1022 H-atom/cm2.

NH_Neg_Err
The negative (lower) error in the best-fit absorbing hydrogen column density, in H-atom/cm2. The errors in the absorption are the two-sided, non-symmetric errors derived by xspec.

NH_Pos_Err
The positive (upper) error in the best-fit absorbing hydrogen column density, in H-atom/cm2. The errors in the absorption are the two-sided, non-symmetric errors derived by xspec.

Spectral_Index
The appropriate parameter (photon index, Gamma, or temperature, kT, in keV) of the best-fit model, depending on which model was fit to the spectrum.

Spectral_Index_Neg_Err
The negative (lower) error in the best-fit spectral index parameter (photon index, Gamma, or temperature, kT, in keV) in the same units as the spectral parameter. The errors in the spectral index are the two-sided, non-symmetric errors derived by xspec.

Spectral_Index_Pos_Err
The positive (upper) error in the best-fit spectral index parameter (photon index, Gamma, or temperature, kT, in keV) in the same units as the spectral parameter. The errors in the spectral index are the two-sided, non-symmetric errors derived by xspec.

Lx_1
The X-ray source luminosity in erg/s derived from the best-fit spectral model for the (first) listed XMM-Newton camera given by the det_instruments parameter. The luminosity given is the mean value of the 90% confidence interval and hence has symmetric errors quoted.

Lx_1_Error
The RMS uncertainty in the X-ray source luminosity, in erg/s, for the (first) listed XMM-Newton camera given by the det_instruments parameter. This is the half-width of the 90% confidence interval for lx_1.

Lx_2
The X-ray source luminosity in erg/s derived from the best-fit spectral model for the second listed XMM-Newton camera (if present) given by the det_instruments parameter. The luminosity given is the mean value of the 90% confidence interval and hence has symmetric errors quoted

Lx_2_Error
The RMS uncertainty in the X-ray source luminosity, in erg/s, for the second listed XMM-Newton camera given by the det_instruments parameter. This is the half-width of the 90% confidence interval for lx_2.

Broad_Type
The classification of the X-ray source. These are the classifications from Pietsch et al. (2005, A&A, 434, 483), where the sources appear in that work. For the 34 sources not in Pietsch et al. (2005) as well as source 238, the present authors give their own classifications (these cases have their broad_type_flag values set to 'a').

The classifications are as follows (see Pietsch et al. (2005, A&A, 434, 483) for the definitions of the hardness ratios HR2, HR3, HR4 and e_HR2 and full details):

     fg Star  = foreground star
    <fg Star> = foreground star candidate
        AGN   = active galactic nucleus
       <AGN>  = AGN candidate
        Gal   = galaxy
        GCl   = galaxy cluster
       <SSS>  = supersoft source candidate in M 31
        SNR   = supernova remnant in M 31
       <SNR>  = supernova remnant candidate in M 31
        GlC   = source in globular cluster
       <GlC>  = source in globular cluster candidate
        XRB   = X-ray binary in M 31
      <hard>  = HR2-e_HR2 > -0.2 or only HR3 and HR4 defined,
                and no other classification
  

Pfh2005_Source_Number
The corresponding X-ray source number from Pietsch et al. (2005).

Broad_Type_Flag
This flag parameter is set to 'a' to indicate that the reference for the broad_type classification is this work, else it is from Pietsch et al. (2005). The meaning of the value of '?' for this parameter is not known to the HEASARC.

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


Contact Person

Questions regarding the M31XMM2 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 20-Oct-2009