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Title: NuSTAR observations of the powerful radio-galaxy Cygnus A

Here, 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 $$\gt 70$$ keV. In gross terms, the NuSTAR spectrum of the AGN has the form of a power law ($${\rm{\Gamma }}\sim 1.6-1.7$$) absorbed by a neutral column density of $${N}_{{\rm{H}}}\sim 1.6\times {10}^{23}\;\;{\mathrm{cm}}^{-2}$$. However, we also detect curvature in the hard ($$\gt 10$$ 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 $${E}_{\mathrm{cut}}\gt 111$$ keV(90% confidence). Interestingly, the absorbed power law plus reflection model leaves residuals suggesting the absorption/emission from a fast ($$15,000-26,000\;\;\mathrm{km}\;\;{{\rm{s}}}^{-1}\;$$), high column-density ($${N}_{W}\gt 3\times {10}^{23}\;\;{\mathrm{cm}}^{-2}$$), highly ionized ($$\xi \sim 2500\;\mathrm{erg}\;\mathrm{cm}\;{{\rm{s}}}^{-1}$$) 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.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [3] ; ORCiD logo [3] ;  [2] ;  [4] ;  [5] ;  [6] ;  [7] ; ORCiD logo [8] ;  [9] ; ORCiD logo [3] ;  [10] ;  [3] ;  [11] ;  [12] ; ORCiD logo [3] ;  [3] ;  [4]
  1. Univ. of Maryland, College Park, MD (United States); Joint Space-Science Institute (JSI), College Park, MD (United States)
  2. Institute of Astronomy, Cambridge (United Kingdom)
  3. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  4. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  6. Georgia Inst. of Technology, Atlanta, GA (United States)
  7. Univ. of California, Berkeley, CA (United States)
  8. Technical Univ. of Denmark, Lyngby (Denmark)
  9. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  10. Columbia Univ., New York, NY (United States)
  11. Univ. of Michigan, Ann Arbor, MI (United States)
  12. Univ. of Maryland, College Park, MD (United States)
Publication Date:
OSTI Identifier:
1313945
Report Number(s):
SLAC-PUB-16797
Journal ID: ISSN 1538-4357; arXiv:1506.07175
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 808; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
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
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; astrophysics; ASTRO; GRQC; accretion; accretion disks; galaxies: clusters: intracluster medium; galaxies: jets; X-rays: individual (Cygnus A)