Chandra and Spitzer unveil heavily obscured quasars in the Chandra/SWIRE survey

Using the large multiwavelength data set in the Chandra/SWIRE Survey (0.6 deg(2) 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 greater than or similar to 10(24) 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 similar to 40% show distinct AGN signatures in their optical/near-infrared SEDs, the remaining being dominated by the host galaxy emission. Only similar to 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.