NuSTAR observations of the powerful radio-galaxy Cygnus A
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA (United Kingdom)
- Infrared Processing and Analysis Center, California Institute of Technology, MC100-22, Pasadena, CA 91125 (United States)
- Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
- Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)
- Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States)
- Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
- DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
- Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
- Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
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{sub H}∼1.6×10{sup 23} cm{sup −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{sub 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{sup −1} ), high column-density (N{sub W}>3×10{sup 23} cm{sup −2}), highly ionized (ξ∼2500 erg cm s{sup −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.
- OSTI ID:
- 22882840
- Journal Information:
- Astrophysical Journal, Vol. 808, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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