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Title: NuSTAR and XMM-Newton observations of NGC 1365: Extreme absorption variability and a constant inner accretion disk

We present a spectral analysis of four coordinated NuSTAR+XMM-Newton observations of the Seyfert galaxy NGC 1365. These exhibit an extreme level of spectral variability, which is primarily due to variable line-of-sight absorption, revealing relatively unobscured states in this source for the first time. Despite the diverse range of absorption states, each of the observations displays the same characteristic signatures of relativistic reflection from the inner accretion disk. Through time-resolved spectroscopy, we find that the strength of the relativistic iron line and the Compton reflection hump relative to the intrinsic continuum are well correlated, which is expected if they are two aspects of the same broadband reflection spectrum. We apply self-consistent disk reflection models to these time-resolved spectra in order to constrain the inner disk parameters, allowing for variable, partially covering absorption to account for the vastly different absorption states that were observed. Each of the four observations is treated independently to test the consistency of the results obtained for the black hole spin and the disk inclination, which should not vary on observable timescales. We find both the spin and the inclination determined from the reflection spectrum to be consistent, confirming that NGC 1365 hosts a rapidly rotating black hole;more » in all cases the dimensionless spin parameter is constrained to be a* > 0.97 (at 90% statistical confidence or better).« less
Authors:
; ; ; ;  [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [6] ; ;  [7] ; ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] more »; « less
  1. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. INAF-Osservatoria Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy)
  3. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  4. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States)
  5. Pontificia Universidad Católica de Chile, Instituto de Astrfísica, Casilla 306, Santiago 22 (Chile)
  6. Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)
  7. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
  8. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  9. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  10. Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
  11. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  12. Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States)
  13. Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy)
Publication Date:
OSTI Identifier:
22356637
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ACCRETION DISKS; BLACK HOLES; COMPTON EFFECT; INCLINATION; IRON; REFLECTION; RELATIVISTIC RANGE; SEYFERT GALAXIES; SPECTRA; SPECTROSCOPY; SPIN; TIME RESOLUTION; X RADIATION