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Optical and near‐infrared observations of hard serendipitous Chandra sources
Author(s) -
Crawford C.S.,
Gandhi P.,
Fabian A.C.
Publication year - 2003
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200310030
Subject(s) - physics , astrophysics , quasar , redshift , galaxy , infrared , astronomy , line (geometry) , near infrared spectroscopy , emission spectrum , spectroscopy , luminous infrared galaxy , photon , spectral line , optics , geometry , mathematics
We have been carrying out a successful observational programme targeted at finding the highly obscured quasars that are thought to be the main contributors to the hard X‐ray background. Out of 56 sources so far studied with optical and near‐infrared imaging and spectroscopy, we have found three definite and a further twelve possible Type II quasars. Few sources show significant line emission, suggesting that the line photons are depleted by the large columns of obscuring matter. The redshift distribution of our sources shows a distinct peak at z ∼ 1. The broad‐band colours and magnitudes of the optical/near‐infrared counterparts indicate that the light in these bands is dominated by the continuum of a massive bright galaxy.