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A rapidly spinning supermassive black hole at the centre of NGC 1365

Risaliti, G. and Harrison, F. A. and Madsen, K. K. and Walton, D. J. and Boggs, S. E. and Christensen, F. E. and Craig, W. W. and Grefenstette, B. W. and Hailey, C. J. and Nardini, E. and Stern, Daniel and Zhang, W. W. (2013) A rapidly spinning supermassive black hole at the centre of NGC 1365. Nature, 494 (7438). pp. 449-451. ISSN 0028-0836. doi:10.1038/nature11938.

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Broad X-ray emission lines from neutral and partially ionized iron observed in active galaxies have been interpreted as fluorescence produced by the reflection of hard X-rays off the inner edge of an accretion disk. In this model, line broadening and distortion result from rapid rotation and relativistic effects near the black hole, the line shape being sensitive to its spin. Alternative models in which the distortions result from absorption by intervening structures provide an equally good description of the data, and there has been no general agreement on which is correct. Recent claims that the black hole (2 × 10^6 solar masses) at the centre of the galaxy NGC 1365 is rotating at close to its maximum possible speed rest on the assumption of relativistic reflection. Here we report X-ray observations of NGC 1365 that reveal the relativistic disk features through broadened Fe-line emission and an associated Compton scattering excess of 10–30 kiloelectronvolts. Using temporal and spectral analyses, we disentangle continuum changes due to time-variable absorption from reflection, which we find arises from a region within 2.5 gravitational radii of the rapidly spinning black hole. Absorption-dominated models that do not include relativistic disk reflection can be ruled out both statistically and on physical grounds.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access
Harrison, F. A.0000-0003-2992-8024
Madsen, K. K.0000-0003-1252-4891
Walton, D. J.0000-0001-5819-3552
Boggs, S. E.0000-0001-9567-4224
Christensen, F. E.0000-0001-5679-1946
Grefenstette, B. W.0000-0002-1984-2932
Nardini, E.0000-0001-9226-8992
Stern, Daniel0000-0003-2686-9241
Zhang, W. W.0000-0002-1426-9698
Additional Information:© 2013 Macmillan Publishers Limited. Received 29 October 2012; Accepted 16 January 2013; Published online 27 February 2013. This work was supported under NASA grant number NNG08FD60C, and made use of data from the Nuclear Spectroscopic Telescope Array (NuSTAR) mission, a project led by Caltech, 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 execution and analysis of these observations. This work also made use of observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. Author Contributions: G.R. is the Principal Investigator of the XMM observations of NGC1365. He led the XMM data analysis and joint spectral analysis, modelling and interpretation of the results. F.A.H. is the Principal Investigator of NuSTAR and led observation planning, execution and participated in scientific interpretation and manuscript preparation. D.J.W. analysed NuSTAR data and participated in modelling and interpretation. K.K.M. led NuSTAR calibration analysis for NGC1365. D.S. is the NuSTAR Project Scientist and participated in definition and interpretation of the observations. B.W.G. assisted in adaptation of the NuSTAR data analysis to NGC1365. E.N. participated in XMM observations, reduction and interpretation. S.E.B., F.E.C., W.W.C., C.J.H. and W.W.Z. led efforts in design, calibration and implementation of NuSTAR. All authors participated in review of the manuscript.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:High-energy astrophysics
Issue or Number:7438
Record Number:CaltechAUTHORS:20130329-085204800
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Official Citation:Risaliti, G., F. A. Harrison, et al. (2013). "A rapidly spinning supermassive black hole at the centre of NGC[thinsp]1365." Nature 494(7438): 449-451.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37683
Deposited By: Tony Diaz
Deposited On:11 Apr 2013 23:58
Last Modified:09 Nov 2021 23:30

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