ACDS V10.0 - Detailed Description of J/MNRAS/461/3443

ACDS V10.0 - Mon Jan 20 05:22:11 CET 2025

| # Detailed Description of J/MNRAS/461/3443 : M31 deepest Chandra catalogue of point sources (Vulic+, 2016) |

Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.

    J/MNRAS/461/3443   M31 deepest Chandra catalogue of point sources (Vulic+, 2016)
    ================================================================================
    X-rays beware: the deepest Chandra catalogue of point sources in M31.
        Vulic N., Gallagher S.C., Barmby P.
       <Mon. Not. R. Astron. Soc., 461, 3443-3456 (2016)>
       =2016MNRAS.461.3443V    (SIMBAD/NED BibCode)
    ================================================================================
    ADC_Keywords: Galaxy catalogs ; X-ray sources

    Keywords: catalogues - galaxies: individual: M31, NGC 224 - X-rays: binaries -
              X-rays: galaxies

    Abstract:
        This study represents the most sensitive Chandra X-ray point source
        catalogue of M31. Using 133 publicly available Chandra ACIS-I/S
        observations totalling ~1Ms, we detected 795 X-ray sources in
        the bulge, north-east, and south-west fields of M31, covering an area
        of ~=0.6deg2, to a limiting unabsorbed 0.5-8.0keV luminosity
        of ~1034erg/s. In the inner bulge, where exposure is
        approximately constant, X-ray fluxes represent average values because
        they were determined from many observations over a long period of
        time. Similarly, our catalogue is more complete in the bulge fields
        since monitoring allowed more transient sources to be detected. The
        catalogue was cross-correlated with a previous XMM-Newton catalogue of
        M31's D25 isophote consisting of 1948 X-ray sources, with only 979
        within the field of view of our survey. We found 387 (49 per cent) of
        our Chandra sources (352 or 44 per cent unique sources) matched to
        within 5 arcsec of 352 XMM-Newton sources. Combining this result with
        matching done to previous Chandra X-ray sources we detected 259. new
        sources in our catalogue. We created X-ray luminosity functions (XLFs)
        in the soft (0.5-2.0keV) and hard (2.0-8.0keV) bands that are the
        most sensitive for any large galaxy based on our detection limits.
        Completeness-corrected XLFs show a break around ~=1.3x1037erg/s,
        consistent with previous work. As in past surveys, we find that the
        bulge XLFs are flatter than the disc, indicating a lack of bright
        high-mass X-ray binaries in the disc and an aging population of
        low-mass X-ray binaries in the bulge.

    Description:
        We have used 133 publicly available Chandra ACIS-I/S observations
        totalling ~1Ms to create the deepest X-ray point source catalogue
        of M31. We detected 795 X-ray sources within our field of view
        (0.6deg2) to a limiting unabsorbed 0.5-8.0keV luminosity of
        ~1034erg/s. Our 90 per cent (0.3-8.0keV) completeness limit
        is 4x1035erg/s.

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × table3.dat       112       29   ACIS-S observations
    × table4.dat       112      102   ACIS-I observations
    × table5.dat       105      795   M31 source list
    × table6.dat       159      794   Additional M31 source properties
    × table8.dat        91      795   X-ray catalogue cross-matches

    See also:
     J/ApJ/577/738   : M31 Chandra X-ray point sources (Kong+, 2002)
     J/ApJ/578/114   : Chandra HRC source in M31 (Kaaret, 2002)
     J/ApJ/609/735   : M31 Chandra X-ray sources (Williams+, 2004)
     J/ApJ/610/247   : M31 supersoft & quasi-soft X-ray sources (Di Stefano+, 2004)
     J/A+A/468/49    : LMXBs in the bulge of M31 (Voss+, 2007)
     J/MNRAS/402/803 : M31 globular cluster system (Peacock+, 2010)
     J/A+A/534/A55   : Deep XMM-Newton Survey of M31 (Stiele+, 2011)
     J/A+A/555/A65   : X-ray variability of M31 central field (Hofmann+, 2013)
     J/ApJ/780/83    : X-ray binaries observed in M31 with Chandra (Barnard+, 2014)
     J/ApJ/802/127   : PHAT stellar cluster survey. II. AP catalog (Johnson+, 2015)

    Byte-by-byte Description of file:  table[34].dat

       Bytes Format Units   Label     Explanations

       1-  5  I5    ---     ObsID     ObsID
       7- 16  A10   "date"  Date      Observation date
      18- 25  F8.5  deg     RAdeg     Right ascension (J2000) (1)
      27- 34  F8.5  deg     DEdeg     Declinatin (J2000) (1)
      36- 39  F4.1  arcmin  Dist      Distance from the centre of M31
                                       (J004244.33+411607.50)
      41- 45  I5    ks      Livetime  Livetime (2)
      47- 52  A6    ---     Datamode  Datamode
      54- 59  A6    ---     CCDs      CCD chips that were on during the
                                       observation (3)
      61- 65  F5.1  deg     RAngle    Roll Angle
      67- 68  A2    ---     Reg       Region of the ACIS-S in Fig. 1 (4)
      70- 77  F8.5  pix     Dx        {deltax (5)

      79- 86  F8.5  pix     Dy        {deltay (5)

      88- 95  F8.5  deg     Rot       Rotation (5)
      97-103  F7.5  ---     Scale     Scale Factor (5)
     105-106  I2    ---     Match     Matched Sources (5)
     108-112  A5    ---     Cat       Catalogue (5)

    Note (1): pointing of the optical axis, the RA_PNT and DEC_PNT keywords from
     the level-2 events files.
    Note (2): Total amount of time that CCDs actually observe a source, which
     excludes the dead time (e.g. time it takes to transfer charge from the image
     region to the frame store region).
    Note (3): CCD chips that were on during the observation, where for ACIS-I
     we used chips 0123 (I0-I3) for analysis. Also, ObsID's 1581/82 only had 2
     active CCDs.
    Note (4): Region of the ACIS-S as follows:
     NE = north-east
     B1 = left (north-east) of the bulge
     B2 = bulge centre
     B3 = right (south-west) of the bulge
     SW = south-west
    Note (5): These parameters summarize the results from matching each ObsID to a
     reference astrometric catalogue (see Section 2.2 for details)
     using the tool wcs_match.

    Byte-by-byte Description of file:  table5.dat

       Bytes Format Units   Label     Explanations

       1-  3  I3    ---     Seq       Source sequential number
       5- 22  A18   ---     CXOU      CXOU J name (HHMMSS.ss+DDMMSS.s)
      24- 32  F9.6  deg     RAdeg     Right ascension (J2000)
      34- 42  F9.6  deg     DEdeg     Declination (J2000)
      44- 48  F5.2  arcmin  Dist      Distance from the centre of M31
                                       (J004244.33+411607.50)
      50- 52  F3.1  arcsec  ePos      Positional uncertainty (1)
      54- 57  F4.1  arcmin  theta     Average off-axis angle for merged observations
      59- 61  I3    ---     Nobs      Number of observations extracted
      63- 68  A6    ---     Det       Detector in which the source was detected,
                                       ACIS-I, ACIS-S, or Both
      70- 71  A2    ---     Reg       Region for a source detected in ACIS-S or Both
      73- 75  I3    ks      Texp      Total exposure time for merged observations
      77- 84  E8.2  s.cm+2  TexpMap   Totat exposure map for merged observations
      86- 89  F4.1  pix     Rsrc      Average radius of the source extraction region
                                       (in sky pixel =  0.492")
      91- 95  F5.1  ----    SNR       Photometric significance
                                       (net counts / upper error on net counts)
                                       (0.3-8.0keV)
      97-100  F4.1  keV     Emed      Background-corrected median photon energy
                                       (0.3-8.0keV)
     102-105  A4    ---     Match     Cross-match results from Section 3.4:
                                       active galactic nuclei (AGN) or
                                       low-mass X-ray binary (LMXB)

    Note (1): Positional uncertainty psrt({sigma}x2 + {sigma}y2), where the
      single-axis position errors {sigma}x and {sigma}y are estimated from the
      standard deviations of the PSF in the extraction region and the number of
      counts extracted.

    Byte-by-byte Description of file:  table6.dat

       Bytes Format Units   Label     Explanations

       1-  3  I3    ---     Seq       Source sequential number
       5- 12  E8.4  ---     pnsT      Poisson probability of a detection not being
                                       a source in total band (0.5-8.0keV)
      14- 21  E8.4  ---     pnsS      Poisson probability of a detection not being
                                        a source in soft band (0.5-2.0keV)
      23- 30  E8.4  ---     pnsH      Poisson probability of a detection not being
                                        a source in hard band (2.0-8.0keV)
      32- 40  F9.2  ct      NCT       Net counts in total band (0.5-8.0keV)
      42- 47  F6.2  ct      E_NCT     Error in NCT (90% upper value)
      49- 54  F6.2  ct      e_NCT     Error in NCT (90% lower value)
      56- 63  F8.2  ct      NCS       Net counts in soft band (0.5-2.0keV)
      65- 70  F6.2  ct      E_NCS     Error in NCS (90% upper value)
      72- 77  F6.2  ct      e_NCS     ?=99.99 Error in NCS (90% lower value)
      79- 86  F8.2  ct      NCH       Net counts in hard band (2.0-8.0keV)
      88- 93  F6.2  ct      E_NCH     Error in NCH (90% upper value)
      95-100  F6.2  ct      e_NCH     ?=99.99 Error in NCH (90% lower value)
     102-109  E8.3  mW/m2   FluxT     Flux in total band (0.5-8.0keV) (1)
     111-119  E9.3  mW/m2   FluxH     ?=-9.99 Flux in soft band (0.5-2.0keV) (1)
     121-129  E9.3  mW/m2   FluxS     ?=-9.99  Flux in hard band (2.0-8.0keV) (1)
     131-139  E9.3  mW/m2   FluxTSum  Summed flux in total band (0.5-8.0keV)
     141-149  E9.3  mW/m2   FluxSSum  Summed flux in soft band (0.5-2.0keV)
     151-159  E9.3  mW/m2   FluxHSum  Summed flux in hard band (2.0-8.0keV)

    Note (1): Conversion factors were 5.47, 1.86, and 3.37 in units of
      10-9erg/photons for the full, soft, and hard bands (to convert from photon
      flux in photons/cm2/s to energy flux in erg/cm2/s). The conversion
      factors account for foreground absorption using an absorbed power-law
      spectrum with {Gamma}=1.7 and NH=6.66x1020cm-2. To convert energy
      fluxes to luminosity in erg/s multiply by 7.2x1049((d)/(776kpc))2.cm2.
      For some sources the soft or hard band had <0 counts, and so uncertainties
      could not be determined and are represented as -99.99. By extension, some
      fluxes in the soft or hard band were <0 and so luminosities appear as -9.99.
      Each source has a pns value <1x10-2 in at least one energy band.

    Byte-by-byte Description of file:  table8.dat

       Bytes Format Units   Label       Explanations

       1-  3  I3    ---     Seq         Source sequential number
       5- 22  A18   ---     CXOU        CXOU J name (HHMMSS.ss+DDMMSS.s)
      24- 27  I4    ---     XMMID       ?=- XMM identification number
      29- 36  A8    ---     XMMClass    XMM classification
      38- 41  A4    ---     ChandraCat  Chandra catalog (1)
      43- 48  A6    ---     ChandraID   Identification in Chandra catalog
      50- 59  A10   ---     LMXB1       Peacock et al. (2010, Cat. J/MNRAS/402/803)
                                          globular clusters ID
      61- 64  I4    ---     LMXB2       ?=- Stiele et al. (2011, Cat. J/A+A/534/A55)
                                          field ID
      66- 69  I4    ---     LMXB3       ?=- Stiele et al. (2011, Cat. J/A+A/534/A55)
                                          globular clusters ID
      71- 74  I4    ---     AGN1        ?=- PHAT AGN matching with Andromeda project
                                         identification number from Johnson et al.,
                                         2015, Cat. J/ApJ/802/127,
                                         [JSD2015] AA NNNNN in Simbad
      76- 79  A4    ---     AGN2        DR12 if AGN in SDSS DR12
      81- 84  A4    ---     AGN3        NED if AGN in NED
      86- 91  A6    ---     AGN4        SIMBAD if AGN in Simbad

    Note (1): Chandra catalogs as follows:
      BA   = Barnard et al., 2014, Cat. J/ApJ/780/83, [BGP2014] NNN in Simbad
      DS02 = Di Stefano et al., 2002ApJ...570..618D, [DKG2002] NN in Simbad
      DS04 = Di Stefano et al., 2004, Cat. J/ApJ/610/247, [KGP2002] AA-NN in Simbad
      HO   = Hofmann et al., 2013, Cat. J/A+A/555/A65, [HPH2013] NNN in Simbad
      KA   = Kaaret, 2002, Cat. J/ApJ/578/114, [K2002] JHHMMSS.ss+DDMMSS.s in Simbad
      KO   = Kong et al., 2002, Cat. J/ApJ/577/738, [KGP2002] rN-NNN in Simbad
      VO   = Voss & Gilfanov, 2007, Cat. J/A+A/468/49, [VG2007] NNN in Simbad
      WI   = Williams et al., 2004, Cat. J/ApJ/609/735

    History:
        From electronic version of the journal
    ================================================================================
    (End)                                      Patricia Vannier [CDS]    08-Dec-2017