THEXMM-NEWTONWIDE-FIELD SURVEY IN THE COSMOS FIELD (XMM-COSMOS): DEMOGRAPHY AND MULTIWAVELENGTH PROPERTIES OF OBSCURED AND UNOBSCURED LUMINOUS ACTIVE GALACTIC NUCLEI

Abstract

We report the final optical identifications of the medium-depth (∼60 ks), contiguous (2 deg 2 ) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ∼1800 X-ray sources down to limiting fluxes of ∼5 × 10 −16 , ∼3 × 10 −15 , and ∼7 × 10 −15 erg cm −2 s −1 in the 0.5-2 keV, 2-10 keV, and 5-10 keV bands, respectively (∼1 × 10 −15 , ∼6 × 10 −15 , and ∼1 × 10 −14 erg cm −2 s −1 , in the three bands, respectively, over 50% of the area). The work is complemented by an extensive collection of multiwavelength data from 24 μm to UV, available from the COSMOS survey, for each of the X-ray sources, including spectroscopic redshifts for 50% of the sample, and high-quality photometric redshifts for the rest. The XMM and multiwavelength flux limits are well matched: 1760 (98%) of the X-ray sources have optical counterparts, 1711 (∼95%) have IRAC counterparts, and 1394 (∼78%) have MIPS 24 μm detections. Thanks to the redshift completeness (almost 100%) we were able to constrain the high-luminosity tail of the X-ray luminosity function confirming that the peak of the number density of log L X > 44.5 active galactic nuclei (AGNs) is at z ∼ 2. Spectroscopically identified obscured and unobscured AGNs, as well as normal and star-forming galaxies, present well-defined optical and infrared properties. We devised a robust method to identify a sample of ∼150 high-redshift (z > 1), obscured AGN candidates for which optical spectroscopy is not available. We were able to determine that the fraction of the obscured AGN population at the highest (L X > 10 44 erg s −1 ) X-ray luminosity is ∼15%-30% when selection effects are taken into account, providing an important observational constraint for X-ray background synthesis. We studied in detail the optical spectrum and the overall spectral energy 348 No. 1, 2010 THE XMM-NEWTON WIDE-FIELD SURVEY IN THE COSMOS FIELD 349distribution of a prototypical Type 2 QSO, caught in a stage transitioning from being starburst dominated to AGN dominated, which was possible to isolate only thanks to the combination of X-ray and infrared observations.

Cold dust emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: dependence on luminosity, obscuration and AGN activity

“…A matching radius of 7.5 arcsec is used to associate 850-μm catalogued sources with our AGN sample. The AGN positions in all cases correspond to the optical positions from Brusa et al (2010), which have much smaller uncertainties than the XMM-Newton X-ray positions. Given the errors on the optical positions are likely to be negligible, we follow Ivison et al (2007) and assume that for a signal-to-noise ratio (SNR) of 3.5, the positional uncertainty, σ pos = 0.6×FWHM/SNR.…”

“…The flux limit for the faintest sources detected in the catalogue are 5e-16 erg s −1 cm −2 and 2.5e-15 erg s −1 cm −2 in the 0.5-2 keV and 2-10 keV bands, respectively. We only consider X-ray sources with robust multiwavelength optical and infrared cross-identifications from Brusa et al (2010), which corresponds to ∼98 per cent of the X-ray sources. We make use of the latest spectroscopic and photometric redshifts for these AGN (Salvato et al 2011;Bongiorno et al 2012) together with the corresponding spectroscopic and photometric classifications.…”

“…These X-ray luminosities have been calculated from the hard-band fluxes from Brusa et al (2010) assuming a photon index of = 1.8. In the case of the type 1 AGN that are detected in the soft (0.5-2 keV) band but not in the hard band, the soft X-ray fluxes from Brusa et al (2010) are used to estimate the hard X-ray flux, once again assuming = 1.8. We note that no absorption correction has been applied to these luminosities as the X-ray data for the entire sample is in general of insufficient quality to allow full spectral fitting.…”

“…We therefore begin by testing how the 850-μm flux varies with SFR. Bongiorno et al (2012) have estimated the SFRs for the COSMOS AGN using SED-fitting to the available multiwavelength photometry (Brusa et al 2010) -SFR SED hereafter. These can be used to check the dependence of the 850-μm flux density on SFR.…”

The NuSTAR Extragalactic Surveys: X-Ray Spectroscopic Analysis of the Bright Hard-band Selected Sample

“…Objects from the deep fields all have unique counterparts at lower energies from either the Chandra (Lehmer et al 2005;Xue et al 2011;Civano et al 2012Civano et al , 2016Goulding et al 2012) or XMM-Newton (Brusa et al 2010;Ranalli et al 2013) surveys of these same fields, with the exception of one source in the ECDF-S field (ecdfs5; this source has two possible counterparts, one at low and one at high redshift; see Table 2 and Appendix).…”