Sambruna, R. M. and Reeves, J. N. and Braito, V. and Lewis, K. T. and Eracleous, M. and Gliozzi, M. and Tavecchio, F. and Ballantyne, D. R. and Ogle, P. M. and Barth, A. J. and Tueller, J. (2009) Structure of the accretion flow in broad-line radio galaxies: the case of 3C 390.3. Astrophysical Journal, 700 (2). pp. 1473-1487. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090918-114104086
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We present XMM-Newton and Suzaku observations of the broad-line radio galaxy 3C 390.3 acquired in 2004 October and 2006 December, respectively. An archival Swift BAT spectrum from the 9 month survey is also analyzed, as well as an optical spectrum simultaneous to XMM-Newton. At soft X-rays, no absorption features are detected in the Reflection Grating Spectrometer spectrum of 3C 390.3; a narrow emission line is found at 0.564 keV, most likely originating in the narrow-line region. Both the EPIC and XIS data sets confirm the presence of an Fe Kα emission line at 6.4 keV with equivalent width (EW) = 40 eV. The Fe Kα line has a width FWHM ∼ 8800 km s^−1, consistent within a factor of 2 with the width of the double-peaked Hα line, suggesting an origin from the broad-line region. The data show for the first time a weak, broad bump extending from 5 to 7 keV. When fitted with a Gaussian, its centroid energy is 6.6 keV in the source’s rest frame with FWHM of 43,000 km s^−1 and EW of 50 eV; its most likely interpretation is emission from He-like Fe (Fe xxv), suggesting the presence of an ionized medium in the inner regions of 3C 390.3. The broadband 0.5–100 keV continuum is well described by a single power law with photon index Γ = 1.6 and cutoff energy 157 keV, plus cold reflection with strength R = 0.5. In addition, ionized reflection is required to account for the 6.6 keV bump in the broadband continuum, yielding an ionization parameter ξ ∼ 2700 erg cm s^−1; the inner radius of the ionized reflector is constrained to be larger than 20r_G, although this result depends on the assumed emissivity profile of the disk. If true, we argue that the lack of broad Fe K emission from within 20r_G indicates that the innermost regions of the disk in 3C 390.3 are obscured and/or poorly illuminated. While the spectral energy distribution (SED) of 3C 390.3 is generally dominated by accretionrelated continuum, during accretion low states the jet can significantly contribute in the optical to X-ray bands via synchrotron self-Compton emission. The Compton component is expected to extend to and peak at GeV gamma rays where it will be detected with the Fermi Gamma-Ray Space Telescope during its first few years of operation.
|Additional Information:||© 2009 The American Astronomical Society (AAS). Received 2009 January 2, accepted for publication 2009 June 2. This research has made use of data obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), provided by NASA’s Goddard Space Flight Center, and of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. R.M.S. acknowledges support from NASA through the Suzaku and XMM Newton programs. We thank Ski Antonucci and G. Ghisellini for interesting e-discussions. Research by A.J.B. is supported by NSF grant AST-0548198. We thank Jenny Greene for assistance with the Keck observations. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.|
|Subject Keywords:||galaxies: active; galaxies: individual: 3C390.3; galaxies: jets; galaxies: nuclei; galaxies: Seyfert|
|Official Citation:||Structure of the Accretion Flow in Broad-Line Radio Galaxies: The Case of 3C 390.3 R. M. Sambruna, J. N. Reeves, V. Braito, K. T. Lewis, M. Eracleous, M. Gliozzi, F. Tavecchio, D. R. Ballantyne, P. M. Ogle, A. J. Barth, and J. Tueller 2009 ApJ 700 1473-1487 doi: 10.1088/0004-637X/700/2/1473|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Joy Painter|
|Deposited On:||21 Sep 2009 22:16|
|Last Modified:||26 Dec 2012 11:24|
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