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The high-Eddington NLS1 Ark 564 has the coolest corona

Kara, E. and García, J. A. and Lohfink, A. and Fabian, A. C. and Reynolds, C. S. and Tombesi, F. and Wilkins, D. R. (2017) The high-Eddington NLS1 Ark 564 has the coolest corona. Monthly Notices of the Royal Astronomical Society, 468 (3). pp. 3489-3498. ISSN 0035-8711. doi:10.1093/mnras/stx792.

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Ark 564 is an archetypal Narrow line Seyfert 1 that has been well observed in soft X-rays from 0.3-10 keV, revealing a steep spectrum, strong soft excess, iron K emission line and dramatic variability on the order of hours. Because of its very steep spectrum, observations of the source above 10 keV have been sparse. We report here on the first NuSTAR observation of Ark 564. The source was observed for 200 ks with NuSTAR, 50 ks of which were concurrent with Suzaku observations. NuSTAR and Suzaku observed a dramatic flare, in which the hard emission is clearly delayed with respect to the soft emission, consistent with previous detections of a low-frequency hard lag found in XMM-Newton data. The NuSTAR spectrum is well described by a low-temperature Comptonisation continuum (with an electron temperature of 15 +/- 2 keV), which irradiates a highly ionised disc. No further relativistic broadening or ionized absorption is required. These spectral results show that Ark 564 has one of the lowest temperature coronae observed by NuSTAR to date. We discuss possible reasons for low-temperature coronae in high-Eddington sources.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kara, E.0000-0003-0172-0854
García, J. A.0000-0003-3828-2448
Fabian, A. C.0000-0002-9378-4072
Tombesi, F.0000-0002-6562-8654
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 March 28. Received 2017 March 27; in original form 2017 January 17. Published: 30 March 2017. EK thanks Julian Malzac, Pierre-Olivier Petrucci, Andrea Marinucci and the participants of the FERO8 meeting in Moravia, Czech Republic for interesting discussions on accretion disc coronae. EK thanks the NuSTAR GO Programme for support under grant NNX15AV26G. EK thanks the Hubble Fellowship Programme. Support for Programme number HST-HF2-51360.001-A was provided by NASA through a Hubble Fellowship grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. ACF acknowledges ERC Advanced Grant 340442. CSR acknowledges support from NASA under grant NNX17AF29G.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
European Research Council (ERC)340442
Subject Keywords:black hole physics – galaxies: active – X-rays: individual: Ark 564
Issue or Number:3
Record Number:CaltechAUTHORS:20170331-101614336
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Official Citation:E. Kara, J. A. García, A. Lohfink, A. C. Fabian, C. S. Reynolds, F. Tombesi, D. R. Wilkins; The high-Eddington NLS1 Ark 564 has the coolest corona. Mon Not R Astron Soc 2017; 468 (3): 3489-3498. doi: 10.1093/mnras/stx792
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75576
Deposited By: Joy Painter
Deposited On:31 Mar 2017 17:25
Last Modified:15 Nov 2021 16:34

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