A Caltech Library Service

NuSTAR Unveils a Compton-thick Type 2 Quasar in Mrk 34

Gandhi, P. and Baloković, M. and Harrison, F. A. and Walton, D. J. (2014) NuSTAR Unveils a Compton-thick Type 2 Quasar in Mrk 34. Astrophysical Journal, 792 (2). Art. No. 117. ISSN 0004-637X. doi:10.1088/0004-637X/792/2/117.

PDF - Published Version
See Usage Policy.

PDF - Submitted Version
See Usage Policy.

PDF - Erratum
See Usage Policy.


Use this Persistent URL to link to this item:


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 ~ 1044 erg s–1, in contrast to previous low-energy X-ray measurements where L 2-10 lsim 1043 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 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Gandhi, P.0000-0003-3105-2615
Harrison, F. A.0000-0003-2992-8024
Walton, D. J.0000-0001-5819-3552
Additional Information:Grant and fellowship acknowledgments: STFC ST/J003697/1 (P.G.), ST/K501979/1 (G.B.L.), ST/I001573/1 (D.M.A. and A.D.M.), Leverhulme Trust (D.M.A.), NASA Postdoctoral Program (S.H.T), ASI-INAF grant (A.C.), Anillo ACT1101 and FONDECYT 1140304 (P.A.), International Fulbright Science and Technology Award (M.B.), and Swiss National Science Foundation (NSF) grant PP00P2 138979/1 (M.K.). In addition, F.A.H. acknowledges support from a Durham University COFUND fellowship, and F. E. B. acknowledges support from Basal-CATA PFB-06/2007, CONICYT-Chile (FONDECYT 1141218 and “EMBIGGEN” Anillo ACT1101) Project IC120009 “Millennium Institute of Astrophysics (MAS)” funded by the Iniciativa Cient´ıfica Milenio del Ministerio de Econom´ıa, Fomento y Turismo. The authors thank Fred K.Y. Lo for megamaser discussions, and the referee for the report. P.G. thanks James R. Mullaney and Chris M. Harrison for discussions. P.G. is also grateful to Matteo Guainazzi for his comments and insights on the origin of the soft X-ray spectrum. NuSTAR is a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL), and funded by the National Aeronautics and Space Administration (NASA). The NuSTAR Operations, Software, and Calibration teams are acknowledged for support with these observations. This research has made use of the NuSTAR Data Analysis Software (nustardas) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This work has made use of data from XMM-Newton and the Sloan Digital Sky Survey. Figure 5 is based upon data from with the NASA/ESA Hubble Space Telescope and obtained from the Hubble Legacy Archive. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by JPL, Caltech, under contract with NASA. Facilities: NuSTAR, XMM-Newton, Sloan, WISE, HST, Swift, CXO
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/J003697/1
Science and Technology Facilities Council (STFC)ST/K501979/1
Science and Technology Facilities Council (STFC)ST/I001573/1
Leverhulme TrustUNSPECIFIED
NASA Postdoctoral ProgramUNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT1101
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1140304
International Fulbright Science and Technology AwardUNSPECIFIED
Swiss National Science Foundation (SNSF)PP00P2 138979/1
Durham UniversityUNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1141218
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)EMBIGGEN Anillo ACT1101
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
Subject Keywords:galaxies: active; X-rays: galaxies; X-rays: individual (Mrk 34)
Issue or Number:2
Record Number:CaltechAUTHORS:20140925-140514974
Persistent URL:
Official Citation:NuSTAR Unveils a Compton-thick Type 2 Quasar in Mrk 34 P. Gandhi et al. 2014 ApJ 792 117
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50038
Deposited On:26 Sep 2014 14:29
Last Modified:10 Nov 2021 18:51

Repository Staff Only: item control page