skip to main content

Title: NuSTARUnveils a Compton-Thick Type 2 Quasar in MrK 34

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 H lies in the Compton-thick (CT) regime. The new data also show a high intrinsic 2-10 keV luminosity of L 2-10 ~ 10 44 erg s –1, in contrast to previous low-energy X-ray measurements where L 2-10 ≲ 10 43 erg s –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 ismore » 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. In conclusion, 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.« less
ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [2] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ;  [1] ;  [12] ;  [13] ;  [14] ;  [2] ;  [15] more »;  [16] ;  [17] ;  [18] ;  [19] ;  [20] ;  [21] ;  [20] ;  [17] ;  [2] ;  [20] « less
  1. Durham Univ., Durham (United Kingdom)
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  3. Pontificia Univ. Catolica de Chile, Santiago (Chile); Univ. de Valparaiso, Valparaiso (Chile)
  4. Georgia Inst. of Technology, Atlanta, GA (United States)
  5. Pontificia Univ. Catolica de Chile, Santiago (Chile); Space Science Institute, Boulder, CO (United States)
  6. Univ. of California, Berkeley, CA (United States)
  7. The Pennsylvania State Univ., University Park, PA (United States)
  8. Max-Planck-Institut fur extraterrestrische Physik, Garching bei Munchen (Germany)
  9. Technical Univ. of Denmark, Lyngby (Denmark)
  10. INAF Osservatorio Astronomico di Bologna, Bologna (Italy)
  11. Technical Univ. of Denmark, Lyngby (Denmark); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  12. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  13. Institute of Astronomy, Cambridge (United Kingdom)
  14. Columbia Univ., New York, NY (United States)
  15. Dartmouth College, Hanover, NH (United States)
  16. ETH Zurich, Zurich (Switzerland)
  17. Yale Univ., New Haven, CT (United States)
  18. Univ. of California, Berkeley, CA (United States); The Pennsylvania State Univ., University Park, PA (United States)
  19. Stanford Univ., Stanford, CA (United States)
  20. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  21. ASDC-ASI, Roma (Italy); INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone (RM) (Italy)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1538-4357; arXiv:1407.1844
Grant/Contract Number:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 792; Journal Issue: 2; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; Astrophysics; ASTRO; GRQC; galaxies: active; X-rays: galaxies; X-rays: individual (Mrk 34)