학술논문
Chandra and Spitzer Unveil Heavily Obscured Quasars in the Chandra/SWIRE Survey
Document Type
Article
Author
del, Maria; Polletta, Carmen; Wilkes, Belinda J.; Siana, Brian; Lonsdale, Carol J.; Kilgard, Roy; Smith, Harding E.; Kim, Woo; Owen, Frazer; Efstathiou, Andreas; Jarrett, Tom; Stacey, Gordon; Franceschini, Alberto; Rowan, Michael; R, Tom S.; Berta, Stefano; Fang, Fan; Farrah, Duncan; Gonzalez, Eduardo; Morrison, Glenn; Surace, Jason A.; Shupe, Dave L.
Source
The Astrophysical Journal; May 2006, Vol. 642 Issue: 2 p673-693, 21p
Subject
Language
ISSN
0004637X; 15384357
Abstract
Using the large multiwavelength data set in the Chandra/SWIRE Survey (0.6 deg2 in the Lockman Hole), we show evidence for the existence of highly obscured (Compton-thick) AGNs, estimate a lower limit to their surface density, and characterize their multiwavelength properties. Two independent selection methods based on the X-ray and infrared spectral properties are presented. The two selected samples contain (1) five X-ray sources with hard X-ray spectra and column densities [?]1024 cm-2 and (2) 120 infrared sources with red and AGN-dominated infrared SEDs. We estimate a surface density of at least 25 Compton-thick AGNs deg-2 detected in the infrared in the Chandra/SWIRE field, of which ~40% show distinct AGN signatures in their optical/near-infrared SEDs, the remaining being dominated by the host galaxy emission. Only ~33% of all Compton-thick AGNs are detected in the X-rays at our depth [F(0.3-8 keV) > 10-15 ergs cm-2 s-1]. We report the discovery of two sources in our sample of Compton-thick AGNs, SWIRE J104409.95+585224.8 (z = 2.54) and SWIRE J104406.30+583954.1 (z = 2.43), which are the most luminous Compton-thick AGNs at high z currently known. The properties of these two sources are discussed in detail with an analysis of their spectra, SEDs, luminosities, and black hole masses.