J/PASJ/70/S36 X-ray-bright optically faint AGN (Terashima+, 2018) ================================================================================ X-ray-bright optically faint active galactic nuclei in the Subaru Hyper Suprime-Cam wide survey. Terashima Y., Suganuma M., Akiyama M., Greene J.E., Kawaguchi T., Iwasawa K., Nagao T., Noda H., Toba Y., Ueda Y., Yamashita T. =2018PASJ...70S..36T (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Active gal. nuclei ; QSOs ; X-ray sources ; Millimetric/submm sources Keywords: galaxies: active - galaxies:: supermassive black holes - X-rays: galaxies Abstract: We construct a sample of X-ray-bright optically faint active galactic nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared source catalogs. Fifty-three X-ray sources satisfying i-band magnitude fainter than 23.5mag and X-ray counts with the EPIC-PN detector larger than 70 are selected from 9.1 deg^2^, and their spectral energy distributions (SEDs) and X-ray spectra are analyzed. Forty-four objects with an X-ray to i-band flux ratio FX/Fi>10 are classified as extreme X-ray-to-optical flux sources. Spectral energy distributions of 48 among 53 are represented by templates of type 2 AGNs or star-forming galaxies and show the optical signature of stellar emission from host galaxies in the source rest frame. Infrared/optical SEDs indicate a significant contribution of emission from dust to the infrared fluxes, and that the central AGN is dust obscured. The photometric redshifts determined from the SEDs are in the range of 0.6-2.5. The X-ray spectra are fitted by an absorbed power-law model, and the intrinsic absorption column densities are modest (best-fit logNH=20.5-23.5cm^-2^ in most cases). The absorption-corrected X-ray luminosities are in the range of 6x10^42^-2x10^45^erg/s. Twenty objects are classified as type 2 quasars based on X-ray luminosity and NH. The optical faintness is explained by a combination of redshifts (mostly z>1.0), strong dust extinction, and in part a large ratio of dust/gas. Description: The XMM-Newton Large Scale Structure Survey (LSS: Pierre et al., 2004, J. Cosmol. Astropart. Phys., 9, 11) and its extension (the Ultimate XMM-Newton survey, XXL; Pierre et al. 2016A&A...592A...1P, Cat. IX/49) are X-ray surveys covering large consecutive fields (25 deg^2^ in the northern field), which enable us to study large-scale structures and to find rare X-ray-emitting populations. We use a part of the XXL northern field covered by HSC and the Spitzer space telescope. The XMM serendipitous source catalogue data release 6 (3XMM-DR6: Rosen et al., 2016A&A...590A...1R, See Cat. IX/50) is used as an X-ray source catalog. The 3XMM-DR6 catalog utilizes XMM-Newton observations performed by 2015 June 4, and contains some pointed observations in the XXL region with a longer exposure time than those of the original survey. Thus we fully utilize X-ray sources detected in such additional pointings. Since our aims are to select X-ray-bright optically faint sources and understand their nature, we use objects with X-ray counts obtained with the EPIC-PN detector in 0.2-12keV listed in the 3XMM-DR6 catalogue greater than 70 so that X-ray spectral fits can be performed. This count limit roughly corresponds to an X-ray flux of ~10^-14^erg/s/cm^2^ in the 2-10keV band, though conversion to an X-ray flux depends on exposure time and assumed X-ray spectra. If an X-ray source is observed more than twice, the observation giving the largest X-ray counts is used. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 56 53 Results of SED fits table4.dat 70 53 Results of power-law fits to X-ray spectra table5.dat 55 53 Results of absorbed power law fits to X-ray spectra table6.dat 50 53 Flux ratios -------------------------------------------------------------------------------- See also: IX/49 : XXL Survey: First results (Pierre+, 2016) IX/50 : XMM-Newton Serendipitous Source Catalogue 3XMM-DR6 (XMM-SSC, 2016) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 16 A16 --- 3XMM 3XMM name (JHHMMSS.s+DDMMSS) 18- 22 F5.3 --- zph Photometric redshift 24- 27 F4.2 mag AV Extinction in V band 29- 37 A9 --- SED Adopted SED template (1) 39- 42 A4 --- Class1 Classification of SED type (AGN1, AGN2 or SF) 44- 48 F5.3 --- zsp ? Spectroscopic redshift presented in Akiyama et al. (2015PASJ...67...82A) 50- 52 A3 --- Class2 Spectroscopic classification in Akiyama et al. (2015PASJ...67...82A) (2) 54- 56 A3 --- Note [a,bc ] Note (3) -------------------------------------------------------------------------------- Note (1): "+ IR" denotes the existence of infrared excess compared to model in fit without Spitzer data. Note (2): Spectroscopic classification as follows: NLA = narrow-line AGN BLA = broad-line AGN Note (3): Notes as follows: a = Redshift range in fit was restricted to 1