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NuSTAR observations of the powerful radio-galaxy Cygnus A

Reynolds, Christopher S. and Lohfink, Anne M. and Ogle, Patrick M. and Harrison, Fiona A. and Madsen, Kristin K. and Fabian, Andrew C. and Wik, Daniel R. and Madejski, Grzegorz and Ballantyne, David R. and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Fuerst, Felix and Hailey, Charles J. and Lanz, Lauranne and Miller, Jon M. and Saez, Cristian and Stern, Daniel and Walton, Dominic J. and Zhang, William W. (2015) NuSTAR observations of the powerful radio-galaxy Cygnus A. Astrophysical Journal, 808 (2). Art. No. 154. ISSN 0004-637X. doi:10.1088/0004-637X/808/2/154.

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We present NuSTAR observations of the powerful radio galaxy Cygnus A, focusing on the central absorbed active galactic nucleus (AGN). Cygnus A is embedded in a cool-core galaxy cluster, and hence we also examine archival XMM-Newton data to facilitate the decomposition of the spectrum into the AGN and intracluster medium components. NuSTAR gives a source-dominated spectrum of the AGN out to >70 keV. In gross terms, the NuSTAR spectrum of the AGN has the form of a power law (Γ ~ 1.6-1.7) absorbed by a neutral column density of N_H ~ 1.6 x 10^(23) cm^(-2). However, we also detect curvature in the hard (>10 keV) spectrum resulting from reflection by Compton-thick matter out of our line of sight to the X-ray source. Compton reflection, possibly from the outer accretion disk or obscuring torus, is required even permitting a high-energy cut off in the continuum source; the limit on the cut-off energy is E_(cut) > 111 keV(90% confidence). Interestingly, the absorbed power law plus reflection model leaves residuals suggesting the absorption/emission from a fast (15,000-26,000 km s^(-1)), high column-density (N_W > 3 x 10^(23) cm^(-2)), highly ionized (ζ – 2500 erg cm s^(-1)) wind. A second, even faster ionized wind component is also suggested by these data. We show that the ionized wind likely carries a significant mass and momentum flux, and may carry sufficient kinetic energy to exercise feedback on the host galaxy. If confirmed, the simultaneous presence of a strong wind and powerful jets in Cygnus A demonstrates that feedback from radio-jets and sub-relativistic winds are not mutually exclusive phases of AGN activity but can occur simultaneously.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ogle, Patrick M.0000-0002-3471-981X
Harrison, Fiona A.0000-0003-2992-8024
Madsen, Kristin K.0000-0003-1252-4891
Fabian, Andrew C.0000-0002-9378-4072
Wik, Daniel R.0000-0001-8952-676X
Ballantyne, David R.0000-0001-8128-6976
Boggs, Steven E.0000-0001-9567-4224
Christensen, Finn E.0000-0001-5679-1946
Fuerst, Felix0000-0003-0388-0560
Lanz, Lauranne0000-0002-3249-8224
Stern, Daniel0000-0003-2686-9241
Walton, Dominic J.0000-0001-5819-3552
Zhang, William W.0000-0002-1426-9698
Additional Information:© 2015 The American Astronomical Society. Received 2015 March 18; accepted 2015 June 17; published 2015 July 29. We thank the anonymous referee for their thorough and constructive comments that improved the quality of the manuscript. The authors also thank Francesco Tombesi for stimulating conversations throughout the course of this work. C.S.R. thanks NASA for support under grant NNX14AF86G. Our analysis makes use of the XSPEC_EMCEE package developed and distributed by Jeremy Sanders. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of 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). Facilities:NuSTAR, XMM-Newton, Chandra
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:accretion, accretion disks – galaxies: clusters: intracluster medium – galaxies: jets – X-rays: individual (Cygnus A)
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2015-44
Issue or Number:2
Record Number:CaltechAUTHORS:20150802-074905579
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59137
Deposited By: Joy Painter
Deposited On:06 Aug 2015 18:31
Last Modified:10 Nov 2021 22:15

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