Article

<i>NuSTAR</i>AND<i>XMM-NEWTON</i>OBSERVATIONS OF NGC 1365: EXTREME ABSORPTION VARIABILITY AND A CONSTANT INNER ACCRETION DISK

D. J. WaltonCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USAG. RisalitiHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USAFiona A. HarrisonCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USAA. C. FabianInstitute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UKJ. M. MïllerDepartment of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USAP. ArévaloPontificia Universidad Católica de Chile, Instituto de Astrfísica, Casilla 306, Santiago 22, ChileD. R. BallantyneCenter for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USASteven E. BoggsSpace Sciences Laboratory, University of California, Berkeley, CA 94720, USALaura BrennemanHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USAFinn E. ChristensenDTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby, DenmarkWilliam W. CraigSpace Sciences Laboratory, University of California, Berkeley, CA 94720, USAM. ElvisHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USAF. FuerstCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USAP. GandhiDepartment of Physics, Durham University, South Road, Durham DH1 3LE, UKBrian W. GrefenstetteCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USACharles J. HaileyColumbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USAErin KaraInstitute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UKBin LuoDepartment of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802, USAKristin K. MadsenCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USAAndrea MarinucciDipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma, ItalyG. MattDipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma, ItalyM. L. ParkerInstitute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UKC. S. ReynoldsDepartment of Astronomy, University of Maryland, College Park, MD 20742, USAE. RiversCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USAR. R. RossPhysics Department, College of the Holy Cross, Worcester, MA 01610, USADaniel SternJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USAW. W. ZhangNASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

2014en

ABI

Abstract

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; in all cases the dimensionless spin parameter is constrained to be a* > 0.97 (at 90% statistical confidence or better).

Identifiers

DOI: 10.1088/0004-637x/788/1/76

Citations and references

Cited by 30 references

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