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Multi-wavelength observations of serendipitous Chandra sources

P. Gandhi·C. S. Crawford·A. C. Fabian·R. J. Wilman·R. M. Johnstone·A. J. Barger·L. L. Cowie
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Abstract

We describe progress in a programme to study a sample of sources typical of those which contribute a large fraction of the hard X-ray background. The sources are selected from the fields of approximately 10 ks Chandra cluster observations with follow-up in the near-infrared and optical. The X-ray data indicate that many of these are powerful, obscured sources. Two hard objects which are lensed by the cluster are good candidates for X-ray type-2 quasars, with luminosities of the order 10^{44}-10^{45} erg s^{-1} and obscuring column densities of the order 10^{23} cm^{-2}. We find that the sources are bright in the infra-red (K typically 17-18). From Keck optical spectra and photometric redshifts, we find that the host galaxies are consistent with being early-type, massive hosts at redshifts ranging from 0.2 to 3, with median redshift approximately 1.5. The two obscured quasars also have mid-infrared detections and 850-micron upper-limits implying that the surrounding dust is at warm-to-hot temperatures (T of the order of 1000 K).

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P. Gandhi, C. S. Crawford, A. C. Fabian, R. J. Wilman, R. M. Johnstone, A. J. Barger, L. L. Cowie. 2001-06-07. Multi-wavelength observations of serendipitous Chandra sources. https://arxiv.org/abs/astro-ph/0106139

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