J/ApJ/741/49          ULX candidates in nearby galaxies          (Swartz+, 2011)
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A complete sample of ultraluminous X-ray source host galaxies.
    Swartz D.A., Soria R., Tennant A.F., Yukita M.
   <Astrophys. J., 741, 49 (2011)>
   =2011ApJ...741...49S
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ADC_Keywords: Galaxies, nearby ; X-ray sources
Keywords: galaxies: general - surveys - X-rays: binaries - X-rays: galaxies -
          X-rays: general

Abstract:
    One hundred seven ultraluminous X-ray sources (ULXs) with 0.3-10.0keV
    luminosities in excess of 10^39^erg/s are identified in a complete
    sample of 127 nearby galaxies. The sample includes all galaxies within
    14.5Mpc above the completeness limits of both the Uppsala Galaxy
    Catalogue (Cat. VII/26) and the Infrared Astronomical Satellite survey
    (Cat. II/125). The galaxy sample spans all Hubble types, a
    four-decade range in mass, 7.5<log(M/M_{sun}_)<11.4, and in star
    formation rate, 0.0002<SFR(M_{sun}_/yr)<=3.6. ULXs are detected in
    this sample at rates of one per 3.2x10^10^M_{sun}_, one per
    ~0.5M_{sun}_/yr star formation rate, and one per 57Mpc^3^
    corresponding to a luminosity density of ~2x10^37^erg/s/Mpc^3^. At
    these rates we estimate as many as 19 additional ULXs remain
    undetected in fainter dwarf galaxies within the survey volume. An
    estimated 14 objects, or 13%, of the 107 ULX candidates are expected
    to be background sources. The differential ULX luminosity function
    shows a power-law slope {alpha}~-0.8 to -2.0 with an exponential
    cutoff at ~20x10^39^erg/s with precise values depending on the model
    and on whether the ULX luminosities are estimated from their observed
    numbers of counts or, for a subset of candidates, from their spectral
    shapes. Extrapolating the observed luminosity function predicts at
    most one very luminous ULX, L_X_~10^41^erg/s, within a distance as
    small as 100Mpc. The luminosity distribution of ULXs within the local
    universe cannot account for the recent claims of luminosities in
    excess of 2x10^41^erg/s, requiring a new population class to explain
    these extreme objects.

Description:
    Most of the galaxies in the present sample have been observed with the
    Chandra X-Ray Observatory Advanced CCD Imaging Spectrometer (ACIS).
    For consistency, Chandra/ACIS data have been used for analysis when
    available unless a much deeper XMM-Newton observation exists.

File Summary:
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 FileName   Lrecl  Records   Explanations
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ReadMe         80        .   This file
table1.dat     77      107   Properties of ULX candidates
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See also:
 B/chandra : The Chandra Archive Log (CXC, 1999-2012)
 B/xmm     : XMM-Newton Log (XMM-Newton Science Operation Center, 2012)
 VII/113 : Catalogued Galaxies + QSOs observed in IRAS Survey, V2 (IPAC 1989)
 II/125  : IRAS catalogue of Point Sources, Version 2.0 (IPAC 1986)
 VII/26  : Uppsala General Catalogue of Galaxies (UGC) (Nilson 1973)
 J/MNRAS/416/1844 : 2XMM ultraluminous X-ray source candidates (Walton+, 2011)
 J/ApJ/687/471   : Observational comparison between ULXs & XRBs (Berghea+, 2008)
 J/ApJ/664/458   : Spectral fit of ULX sources (Devi+, 2007)
 J/A+A/452/739   : ULX sources and FIRST radio sources (Sanchez-Sutil+, 2006)
 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/157/59   : Ultraluminous X-ray sources in nearby galaxies (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)

Byte-by-byte Description of file: table1.dat
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   Bytes Format Units   Label Explanations
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   1-  2  I2    h       RAh   Hour of right ascension (J2000)
   4-  5  I2    min     RAm   Minute of right ascension (J2000)
   7- 11  F5.2  s       RAs   Second of right ascension (J2000)
      13  A1    ---     DE-   Sign of declination (J2000)
  14- 15  I2    deg     DEd   Degree of declination (J2000)
  17- 18  I2    arcmin  DEm   Arcminute of declination (J2000)
  20- 23  F4.1  arcsec  DEs   Arcsecond of declination (J2000)
  25- 32  A8    ---     Gal   Putative host galaxy name (NGC, IC or UGC number)
  34- 37  F4.1  Mpc     Dist  [3.1/14.5] Putative host galaxy distance
  39- 42  F4.2  ---     r/D25 [0.01/0.93] Radial position of ULX (1)
  44- 53  A10   ---     ObsID Observation identifier (Chandra or XMM)
  55- 60  F6.1  ct      Cts   [14/9034]? Detected X-ray source counts (2)
  62- 65  F4.1  ---     S/N   [3.2/82.4]? Signal to noise ratio (2)
  67- 70  F4.1  10+32W  Lcts  [0.2/21.4]? Unabsorbed 0.3-10.0keV luminosity
                              estimated from source counts in 10^39^erg/s (3)
  72- 75  F4.1  10+32W  Lx    [1/36]? Unabsorbed 0.3-10.0keV luminosity
                              estimated from model fits in 10^39^erg/s (4)
      77  I1    ---     Ref   [1/4]? Reference (5)
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Note (1): Radial position within host galaxy expressed as fraction of D_25_
          radius. See figure 4.
Note (2): Source-finding was applied to events in the 0.3-6.0keV range for
          Chandra observations, in the 0.5-4.5keV range for XMM-Newton
          observations, and in the full 0.1-2.4keV range for ROSAT observations.
          The different ranges were chosen as those that tend to maximize
          signal-to-noise ratio (S/N). See section 3.3.
Note (3): Unabsorbed 0.3-10.0keV luminosity estimated from source counts
          detected in the 0.3-6.0keV band and assuming an absorbed power-law
          spectrum of {Gamma}=1.7 and a Galactic column density.
Note (4): Unabsorbed 0.3-10.0keV luminosity estimated from model fits to the
          X-ray spectral energy distribution as given by the references in
          Column Ref.
Note (5): Reference as follows:
   1 = Feng & Kaaret 2009ApJ...696.1712F;
   2 = Roberts et al. 2004MNRAS.349.1193R;
   3 = Walton et al. 2011MNRAS.414.1011W;
   4 = Sutton et al. 2011AN....332..362S
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History:
    From electronic version of the journal

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(End)                                     Emmanuelle Perret [CDS]    20-Feb-2013