posted on 2017-11-29, 09:53authored byC. Ricci, R. J. Assef, D. Stern, R. Nikutta, D. M. Alexander, D. Asmus, D. R. Ballantyne, F. E. Bauer, A. W. Blain, S. Boggs, P. G. Boorman, W. N. Brandt, M. Brightman, C. S. Chang, C-T. J. Chen, F. E. Christensen, A. Comastri, W. W. Craig, T. Diaz-Santos, P. R. Eisenhardt, D. Farrah, P. Gandhi, C. J. Hailey, F. A. Harrison, H. D. Jun, M. J. Koss, S. LaMassa, G. B. Lansbury, C. B. Markwardt, M. Stalevski, F. Stanley, E. Treister, C-W. Tsai, D. J. Walton, J. W. Wu, L. Zappacosta, W. W. Zhang
Hot dust-obscured galaxies (hot DOGs), selected from Wide-Field Infrared Survey Explorer’s all-sky infrared
survey, host some of the most powerful active galactic nuclei known and may represent an important stage in the
evolution of galaxies. Most known hot DOGs are located at z > 1.5, due in part to a strong bias against identifying
them at lower redshift related to the selection criteria. We present a new selection method that identifies 153 hot
DOG candidates at z ~ 1, where they are significantly brighter and easier to study. We validate this approach by
measuring a redshift z = 1.009 and finding a spectral energy distribution similar to that of higher-redshift hot
DOGs for one of these objects, WISE J1036+0449 ( LBol ~= 8 x 10^46 erg s^-1). We find evidence of a broadened
component in Mg II, which would imply a black hole mass of MBH ~= 2 x 10^8 M(solar) and an Eddington ratio of
LambdaEdd ~= 2.7. WISE J1036+0449 is the first hot DOG detected by the Nuclear Spectroscopic Telescope Array, and
observations show that the source is heavily obscured, with a column density of NH = 2-15 x 10^23 cm^-2 . The
source has an intrinsic 2–10 keV luminosity of ~ 6 x 10^44 erg s^-1, a value significantly lower than that expected
from the mid-infrared/X-ray correlation. We also find that other hot DOGs observed by X-ray facilities show a
similar deficiency of X-ray flux. We discuss the origin of the X-ray weakness and the absorption properties of hot
DOGs. Hot DOGs at z ~< 1 could be excellent laboratories to probe the characteristics of the accretion flow and of
the X-ray emitting plasma at extreme values of the Eddington ratio.
Funding
This work makes use of data products from the Wide-Field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology (Caltech). WISE is funded by the National Aeronautics and Space Administration (NASA). Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership between Caltech, the University of California, and NASA. Use of the observatory was made possible by the generous financial support of the W.M. Keck Foundation. This work makes use of data from the NuSTAR mission, a project led by Caltech, managed by the Jet Propulsion Laboratory, and funded by NASA. We thank the NuSTAR Operations, Software, and Calibration teams for their support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software, jointly developed by the ASI Science Data Center (Italy) and Caltech. This work has made use of the NASA/IPAC Infrared Science Archive and NASA/IPAC Extragalactic Database, which are operated by the Jet Propulsion Laboratory, Caltech, under contract with NASA. This material is based upon work supported by NASA under Proposal No. 13-ADAP13-0092, issued through the Astrophysics Data Analysis Program. We thank M. Karouzos and C.S. Chang for their comments on the manuscript. We acknowledge financial support from CONICYT-Chile grants "EMBIGGEN" Anillo ACT1101 (C.R., E.T., F.E.B.); FONDECYT 1141218 (C.R., F.E.B.), 3140436 (R.N.), and 1151408 (R.A.); and Basal-CATA PFB–06/2007 (C.R., F.E.B., E.T.) and from the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to the Millennium Institute of Astrophysics (F.E.B.). C.R. acknowledges support from the China-CONICYT fund. P.G. thanks the STFC for their support [grant reference ST/J003697/2], and W.N.B. acknowledges financial support from NuSTAR sub
History
Citation
Astrophysical Journal, 2017, 835 (1)
Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy