The mid-infrared properties of X-ray sources

V. Gorjian, M. Brodwin, C. S. Kochanek, S. Murray, D. Stern, K. Brand, P. R. Eisenhardt, M. L.N. Ashby, P. Barmby, M. J.I. Brown, A. Dey, W. Forman, B. T. Jannuzi, C. Jones, A. T. Kenter, M. A. Pahre, J. C. Shields, M. W. Werner, S. P. Willner

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We combine the results of the Spitzer IRAC Shallow Survey and the Chandra XBoötes Survey of the 8.5 deg2 Boötes field of the NOAO Deep Wide-Field Survey to produce the largest comparison of mid-IR and X-ray sources to date. The comparison is limited to sources with X-ray fluxes >8 × 10-15 ergs cm-2 s-1 in the 0.5-7.0 keV range and mid-IR sources with 3.6 μm fluxes brighter than 18.4 mag (12.3 μJy). In this most sensitive IRAC band, 85% of the 3086 X-ray sources have mid-IR counterparts at an 80% confidence level based on a Bayesian matching technique. Only 2.5%) of the sample have no IRAC counterpart at all based on visual inspection. Even for a smaller but a significantly deeper Chandra survey in the same field, the IRAC Shallow Survey recovers most of the X-ray sources. A majority (65%) of the Chandra sources detected in all four IRAC bands occupy a well-defined region of IRAC [3.6] - [4.5] versus [5.8] - [8.0] color-color space. These X-ray sources are likely infrared-luminous, unobscured type I AGNs with little mid-infrared flux contributed by the AGN host galaxy. Of the remaining Chandra sources, most are lower luminosity type I and type II AGNs whose mid-IR emission is dominated by the host galaxy, while approximately 5% are either Galactic stars or very local galaxies.

Original languageEnglish (US)
Pages (from-to)1040-1046
Number of pages7
JournalAstrophysical Journal
Issue number2
StatePublished - Jun 1 2008


  • Galaxies: Seyfert
  • Galaxies: nuclei
  • Infrared: galaxies
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The mid-infrared properties of X-ray sources'. Together they form a unique fingerprint.

Cite this