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J/ApJ/717/1181         Spitzer power-law galaxies in EGS           (Park+, 2010)
AEGIS: a multiwavelength study of Spitzer power-law galaxies.
    Park S.Q., Barmby P., Willner S.P., Ashby M.L.N., Fazio G.G.,
    Georgakakis A., Ivison R.J., Konidaris N.P., Miyazaki S., Nandra K.,
    Rosario D.J.
   <Astrophys. J., 717, 1181-1201 (2010)>
   =2010ApJ...717.1181P
ADC_Keywords: Active gal. nuclei ; Photometry, infrared ; X-ray sources ;
              Cross identifications ; Redshifts
Keywords: galaxies: active - infrared: galaxies - X-rays: galaxies


Abstract:
    This paper analyzes a sample of 489 Spitzer/Infrared Array Camera
    (IRAC) sources in the Extended Groth Strip (EGS), whose spectral
    energy distributions fit a red power law (PL) from 3.6 to 8.0um. The
    median redshift for sources with known redshifts is <z≥1.6. Though
    all or nearly all of the sample galaxies are likely to be active
    galactic nuclei (AGNs), only 33% were detected in the EGS X-ray survey
    (AEGIS-X) using 200ks Chandra observations. The detected sources are
    X-ray luminous with LX>1043erg/s and moderately to heavily
    obscured with NH>1022cm-2. Stacking the X-ray-undetected sample
    members yields a statistically significant X-ray signal, suggesting
    that they are on average more distant or more obscured than sources
    with X-ray detections. The ratio of X-ray to mid-infrared fluxes
    suggests that a substantial fraction of the sources undetected in
    X-rays are obscured at the Compton-thick level, in contrast to the
    X-ray-detected sources, all of which appear to be Compton thin.

Description:
    IRAC observations of the EGS were obtained in 2003-2004 as part of
    Guaranteed Time Observation (GTO) program 8. Barmby et al. (2008, Cat.
    J/ApJS/177/431) give details of the observations and reductions and
    list source photometry in a variety of apertures. This paper uses the
    photometry in the 3.06" diameter aperture.
    The IRAC data are supplemented by observations from the Far-Infrared
    Deep Extragalactic Legacy (FIDEL; dated 2008 August 28) project taken
    with the Multiband Imaging Photometer (MIPS) aboard Spitzer.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat        99      489   Properties of power-law AGNs


See also:
  J/ApJS/193/30   : UV-to-FIR analysis of sources in the EGS. II. (Barro+, 2011)
  J/ApJS/193/13   : Spitzer/IRAC sources in the EGS I. SEDs (Barro+, 2011)
  J/ApJS/180/102  : AEGIS-X: Chandra deep survey (Laird+, 2009)
  J/AJ/137/179    : AGNs in the EGS Survey (Ramos Almeida+, 2009)
  J/ApJS/177/431  : Mid-IR sources in EGS (Barmby+, 2008)
  J/MNRAS/382/109 : Massive galaxies in Extended Groth Strip (Trujillo+, 2007)
  J/AJ/132/2159   : IRAC counterparts of 6cm galaxies in EGS (Willner+, 2006)
  J/ApJ/642/126   : Mid-IR observations in the EGS (Barmby+, 2006)
  http://irsa.ipac.caltech.edu/data/SPITZER/docs/spitzermission/
  observingprograms/legacy/fidel/ : FIDEL data online page


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label   Explanations

   1-  3  I3    ---     EGSPL   Extended Groth Strip Power Law identification
   5- 23  A19   ---    EGSIRAC  IRAC Extended Groth Strip identification (1)
  25- 29  F5.2  ---     alphai  The 3.6-8 micron power-law spectral index (2)
  31- 34  F4.2  ---     Pi      The 3.6-8 micron probability (3)
  36- 40  F5.2  ---     alpham  ? The 3.6-24 micron power-law spectral index (2)
  42- 45  F4.2  ---     Pm      ? The 3.6-24 micron probability (3)
  47- 50  F4.2  ---     z       ? Redshift
  52- 57  F6.2  uJy     S3.6    Spitzer/IRAC 3.6 micron flux density (4)
  59- 64  F6.2  uJy     S4.5    Spitzer/IRAC 4.5 micron flux density (4)
  66- 72  F7.2  uJy     S5.8    Spitzer/IRAC 5.8 micron flux density (4)
  74- 80  F7.2  uJy     S8.0    Spitzer/IRAC 8.0 micron flux density (4)
  82- 88  F7.2  uJy     S24     ? Spitzer/MIPS 24 micron flux density
  90- 93  I4    ---     L09     ? X-ray catalog identification (159 sources) (5)
  95- 99  F5.2  [10-7W] LX      ? Log 2-10keV band luminosity; in erg/s

Note (1): From the catalog published by Barmby et al. (2008,
          Cat. J/ApJS/177/431; <EGSIRAC JHHMMSS.ss+DDMMSS.s> in Simbad).
Note (2): Sν∝να. α≤-0.5 is required for
          selection as a power law (PL) AGN.
Note (3): Goodness of fit expressed as a probability. The numerical value is
          the probability that observations of a source with a power-law SED
          would give the actual chi-square or larger. Px>0.1 is required for
          selection as a power law (PL) AGN.
Note (4): IRAC flux densities in this table were measured in 3 arcsec diameter
          apertures and are the ones used in this paper. They are 3% higher
          than the final published values (Barmby et al. 2008,
          Cat. J/ApJS/177/431), which should be used for future work.
Note (5): X-ray catalog identification from Laird et al. 2009,
          Cat. J/ApJS/180/102, <[LNG2009] egs-NNNN> in Simbad.


History:
    From electronic version of the journal
(End)                 Greg Schwarz [AAS], Emmanuelle Perret [CDS]    06-Jun-2012