Bibcode
DOI
Franceschini, Alberto; Manners, James; Polletta, Maria del Carmen; Lonsdale, Carol; Gonzalez-Solares, Eduardo; Surace, Jason; Shupe, Dave; Fang, Fan; Xu, C. Kevin; Farrah, Duncan; Berta, Stefano; Rodighiero, Giulia; Perez-Fournon, Ismael; Hatziminaoglou, Evanthia; Smith, Harding E.; Siana, Brian; Rowan-Robinson, Michael; Nandra, Kirpal; Babbedge, Tom; Vaccari, Mattia; Oliver, Seb; Wilkes, Belinda; Owen, Frazer; Padgett, Deborah; Frayer, Dave; Jarrett, Tom; Masci, Frank; Stacey, Gordon; Almaini, Omar; McMahon, Richard; Johnson, Olivia; Lawrence, Andrew; Willott, Chris
Bibliographical reference
The Astronomical Journal, Volume 129, Issue 5, pp. 2074-2101.
Advertised on:
5
2005
Citations
75
Refereed citations
67
Description
We exploit deep combined observations with Spitzer and Chandra of the
Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) in the ELAIS N1
region to investigate the nature of the faint X-ray and IR sources in
common, to identify active galactic nucleus (AGN)/starburst diagnostics,
and to study the sources of the X-ray and IR cosmic backgrounds (XRB and
CIRB). In the 17'×17' area of the Chandra
ACIS-I image there are approximately 3400 SWIRE near-IR sources with 4
σ detections in at least two Infrared Array Camera (IRAC) bands
and 988 sources detected at 24 μm with the Multiband Imaging
Photometer (MIPS) brighter than S24~=0.1 mJy. Of these, 102
IRAC and 59 MIPS sources have Chandra counterparts, out of a total of
122 X-ray sources present in the area with
S0.5-8keV>10-15 ergs cm-2
s-1. We have constructed spectral energy distributions (SEDs)
for each source using data from the four IRAC wavebands, Chandra fluxes
in the hard (2-8 keV) and soft (0.5-2 keV) X-rays, and optical follow-up
data in the wavebands U, g', r', i', Z, and H. We fit a number of
spectral templates to the SEDs at optical and IR wavelengths to
determine photometric redshifts and spectral categories and also make
use of diagnostics based on the X-ray luminosities, hardness ratios,
X-ray to IR spectral slopes, and optical morphologies. Although we have
spectroscopic redshifts for only a minority of the Chandra sources (10
type 1 QSOs or Seyfert sources and three galaxies), the available SEDs
constrain the redshifts for most of the sample sources, which turn out
to be typically at 0.5