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Published October 10, 2018 | Accepted Version
Journal Article Open

NuSTAR view of the central region of the Perseus cluster

Abstract

Located at the center of the Perseus cluster, 3C 84 is an extremely bright and nearby radio galaxy. Because of the strong diffuse thermal emission from the cluster in X-rays, the detailed properties and the origin of a power-law component from the central active galactic nucleus (AGN) remains unclear in the source. We report here the first NuSTAR observations of 3C 84. The source was observed for 24.2 and 32 ks on 2018 February 1 and 4, respectively. NuSTAR observations spectrally decompose the power-law AGN component above 10 keV. The power-law component dominates the spectrum above 20 keV with a photon index ~1.9 and an energy flux F_(20–30 keV) = 1.0 × 10^(−11) erg cm^(−2) s^(−1), corresponding to an isotropic luminosity, L_(20–30 keV) = 7.4 × 10^(42) erg s^(−1). We discuss possible emitting sites for the power-law component. The expected thermal emission from the accretion disk is not hot enough to account for the hard X-rays detected from the source. Similar X-ray and γ-ray photon indices and long-term flux variations, the absence of cutoff energy in the hard X-ray spectrum of the source, correlated hard X-ray flux and hardness ratio variations, and the similarity of optical-X-ray slope to blazar rather than Seyfert galaxies supports the hard X-ray power-law component originating from the jet.

Additional Information

© 2018 The American Astronomical Society. Received 2018 July 19; revised 2018 September 14; accepted 2018 September 26; published 2018 October 11. This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association through a contract with NASA. B.R. thanks Erin Kara, Mihoko Yukita, Dave Thompson, Stefan Walker, Amy Lien, Hans Krimm, and Chris Shrader, for interesting discussions about AGN disks and coronas.

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