/A+A/576/A130  Ultra-deep catalog of X-ray groups in ECDF-S (Finoguenov+, 2015)
Ultra-deep catalog of X-ray groups in the Extended Chandra Deep Field-South.
    Finoguenov A., Tanaka M., Cooper M., Allevato V., Cappelluti N., Choi A.,
    Heymans C., Bauer F.E., Ziparo F., Ranalli P., Silverman J., Brandt W.N.,
    Xue Y.Q., Mulchaey J., Howes L., Schmid C., Wilman D., Comastri A.,
    Hasinger G., Mainieri V., Luo B., Tozzi P., Rosati P., Capak P., Popesso P.
   <Astron. Astrophys., 576, A130-130 (2015)>
   =2015A&A...576A.130F
ADC_Keywords: Galaxy catalogs ; X-ray sources

Keywords: gravitational lensing: weak - X-rays: galaxies: clusters -
          large-scale structure of Universe

Abstract:
    We present the detection, identification and calibration of extended
    sources in the deepest X-ray dataset to date, the Extended Chandra
    Deep Field South (ECDF-S). Ultra-deep observations of ECDF-S with
    Chandra and XMM-Newton enable a search for extended X-ray emission
    down to an unprecedented flux of 2x10-16ergs/s/cm2. By using
    simulations and comparing them with the Chandra and XMM data, we show
    that it is feasible to probe extended sources of this flux level,
    which is 10000 times fainter than the first X-ray group catalogs of
    the ROSAT all sky survey. Extensive spectroscopic surveys at the VLT
    and Magellan have been completed, providing spectroscopic
    identification of galaxy groups to high redshifts. Furthermore,
    available HST imaging enables a weak-lensing calibration of the group
    masses. We present the search for the extended emission on spatial
    scales of 32" in both Chandra and XMM data, covering 0.3 square
    degrees and model the extended emission on scales of arcminutes. We
    present a catalog of 46 spectroscopically identified groups, reaching
    a redshift of 1.6. We show that the statistical properties of ECDF-S,
    such as logN-logS and X-ray luminosity function are broadly consistent
    with LCDM, with the exception that dn/dz/dΩ test reveals that a
    redshift range of 0.2<z<0.5 in ECDF-S is sparsely populated. The lack
    of nearby structure, however, makes studies of high-redshift groups
    particularly easier both in X-rays and lensing, due to a lower level
    of clustered foreground. We present one and two point statistics of
    the galaxy groups as well as weak-lensing analysis to show that the
    detected low-luminosity systems are indeed low-mass systems. We verify
    the applicability of the scaling relations between the X-ray
    luminosity and the total mass of the group, derived for the COSMOS
    survey to lower masses and higher redshifts probed by ECDF-S by means
    of stacked weak lensing and clustering analysis, constraining any
    possible departures to be within 30% in mass. Ultra-deep X-ray surveys
    uniquely probe the low-mass galaxy groups across a broad range of
    redshifts. These groups constitute the most common environment for
    galaxy evolution. Together with the exquisite data set available in
    the best studied part of the Universe, the ECDF-S group catalog
    presented here has an exceptional legacy value.

Description:
    The ECDF-S area has been a frequent target of X-ray observations with
    both Chandra and XMM. After the first 1Ms Chandra observation
    (Giacconi et al., 2002, Cat. J/ApJS/139/369), the area was named the
    Chandra Deep Field South. The extension of the CDF-S survey to 2Ms
    (Luo et al., 2008, Cat. J/ApJS/179/19) and later to 4Ms of exposure
    time (Xue et al., 2011, Cat. J/ApJS/195/10), via a large Director's
    Discretionary Time project, has now provided our most sensitive
    0.5-8keV view of the distant AGNs and galaxies. This paper does not
    include the 3Ms Chandra observations of the field taken in 2014.

    For cataloguing the groups, we also include the ECDF-S data (Lehmer et
    al., 2005, Cat. J/ApJS/161/21), which consist of four Chandra ACIS-I
    pointings, 250ks each, defining the square shape of the exposure and
    sensitivity maps.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table4.dat        99       51   Catalog of the ECDF-S X-ray selected galaxy groups


See also:
   J/ApJS/139/369 : Chandra Deep Field South. 1 Ms catalog (Giacconi+, 2002)
   J/ApJS/161/21  : Extended Chandra Deep Field-South survey (Lehmer+, 2005)
   J/AJ/131/2373  : Extended Chandra Deep Field-South survey (Virani+, 2006)
   J/ApJS/179/19  : CDFS survey: 2 Ms source catalogs (Luo+, 2008)
   J/ApJS/195/10  : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)


Byte-by-byte Description of file: table4.dat

   Bytes Format Units      Label   Explanations

   1-  6  A6    ---        ID      X-ray identification (number, or Kurk-N)
   8- 23  A16   ---        Name    IAU name (JHHMMSS.s+DDMMSS)
  25- 31  F7.4  deg        RAdeg   X-ray source right ascension (J2000)
  33- 40  F8.4  deg        DEdeg   X-ray source declination (J2000)
  42- 46  F5.3  ---        z       [0.07/1.61] Redshift
  48- 52  F5.2  aW/m2      Flux    [0.07/70] Flux in the 0.5-2keV band (1)
  54- 57  F4.2  aW/m2      e_Flux  rms uncertainty on Flux
  59- 63  I5    ct         Nct     [76/18135] Total net XMM+Chandra counts
                                    in the flux extraction region
  65- 69  F5.2  10+35W     LX      [0.05/97] Rest-frame luminosity in the
                                    0.1-2.4keV band, in 1042erg/s (2)
  71- 75  F5.2  10+35W     e_LX    rms uncertainty on LX
  77- 81  F5.2  10+13Msun  M200    [0.28/10] Estimated total mass (3)
  83- 86  F4.2  10+13Msun  e_M200  rms uncertainty on M200
  88- 90  F3.1  arcmin     r200    [0.6/4.7] Radius corresponding to M200
      92  I1    ---        Qf      [1/5] Quality flag (4)
  94- 95  I2    ---        Nz      [1/49] Number of spectroscopic member
                                    galaxies inside r200, used to evaluate the
                                    mean spectroscopic redshift
  97- 99  I3    km/s       Vdisp   [120/515] Predicted galaxy velocity 
                                    dispersion (5)

Note (1): The flux (in 10-15erg/cm2/s) is extrapolated to an iteratively
  determined r500 (see Finoguenov et al. 2007, J/ApJS/172/182, for details).
  The aperture determining the flux has been defined by the shape of the
  emission on 32" scales, unless it has been manually redefined to avoid
  contamination from other extended sources (cases where this is not 
  possible have Qf=4).
Note (2): where the K-correction assumes the temperature from the scaling
  relations adopted in Finoguenov et al. (2007ApJS..172..182F). The choice of
  the energy band is driven by the available calibrations of the Lx-M relation
  (Leauthaud et al. 2010ApJ...709...97L), yielding an estimated total mass M200.
Note (3): Estimated total mass, M200, defined with respect to the critical
  density, with only the statistical errors quoted. Systematic errors due
  to scatter in the scaling relations are ∼20% (Allevato et al.,
  2012ApJ...758...47A) and the uncertainty on the calibration is 30%,
  as discussed in Sects. 6 and 7.
Note (4): Flag as follows:
   1 = objects of best quality, with centroids derived from the X-ray emission
       and spectroscopic confirmation of the redshift
   2 = objects have large uncertainties in the X-ray center (low statistics or
       source confusion) with their centroids and flux extraction apertures
       positioned on the associated galaxy concentration with spectroscopic
       confirmation
   3 = objects that still require spectroscopic confirmation
   4 = objects that have more than one counterpart along the line of sight
   5 = objects that have doubtful identifications and are only used to access
       systematic errors in the statistical analysis associated with source
       identification
Note (5): based on the Carlberg et al. (1997ApJ...476L...7C) virial relation
   using our total mass estimates.


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