NuSTAR unveils a Compton-thick type 2 quasar in MrK 34
- Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States)
- Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)
- Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)
- Cahill Center for Astrophysics, California Institute of Technology, 1216 East California, Boulevard, Pasadena, CA 91125 (United States)
- Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
- Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
- Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany)
- DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
- INAF Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)
- Columbia Astrophysics Laboratory, Columbia University, 550 W 120th Street, NY 10027 (United States)
- Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States)
We present Nuclear Spectroscopic Telescope Array (NuSTAR) 3-40 keV observations of the optically selected Type 2 quasar (QSO2) SDSS J1034+6001 or Mrk 34. The high-quality hard X-ray spectrum and archival XMM-Newton data can be fitted self-consistently with a reflection-dominated continuum and a strong Fe Kα fluorescence line with equivalent width >1 keV. Prior X-ray spectral fitting below 10 keV showed the source to be consistent with being obscured by Compton-thin column densities of gas along the line of sight, despite evidence for much higher columns from multiwavelength data. NuSTAR now enables a direct measurement of this column and shows that N {sub H} lies in the Compton-thick (CT) regime. The new data also show a high intrinsic 2-10 keV luminosity of L {sub 2-10} ∼ 10{sup 44} erg s{sup –1}, in contrast to previous low-energy X-ray measurements where L {sub 2-10} ≲ 10{sup 43} erg s{sup –1} (i.e., X-ray selection below 10 keV does not pick up this source as an intrinsically luminous obscured quasar). Both the obscuring column and the intrinsic power are about an order of magnitude (or more) larger than inferred from pre-NuSTAR X-ray spectral fitting. Mrk 34 is thus a 'gold standard' CT QSO2 and is the nearest non-merging system in this class, in contrast to the other local CT quasar NGC 6240, which is currently undergoing a major merger coupled with strong star formation. For typical X-ray bolometric correction factors, the accretion luminosity of Mrk 34 is high enough to potentially power the total infrared luminosity. X-ray spectral fitting also shows that thermal emission related to star formation is unlikely to drive the observed bright soft component below ∼3 keV, favoring photoionization instead.
- OSTI ID:
- 22364925
- Journal Information:
- Astrophysical Journal, Vol. 792, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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