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Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654

Masterson, Megan and Kara, Erin and Ricci, Claudio and García, Javier A. and Fabian, Andrew C. and Pinto, Ciro and Kosec, Peter and Remillard, Ronald A. and Loewenstein, Michael and Trakhtenbrot, Benny and Arcavi, Iair (2022) Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654. Astrophysical Journal, 934 (1). Art. No. 35. ISSN 0004-637X. doi:10.3847/1538-4357/ac76c0.

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1ES 1927+654 is a paradigm-defying active galactic nucleus (AGN) and one of the most peculiar X-ray nuclear transients. In early 2018, this well-known AGN underwent a changing-look event, in which broad optical emission lines appeared and the optical flux increased. Yet, by 2018 July, the X-ray flux had dropped by over two orders of magnitude, indicating a dramatic change in the inner accretion flow. With three years of observations with NICER, XMM-Newton, and NuSTAR, we present the X-ray evolution of 1ES 1927+654, which can be broken down into three phases: (1) an early super-Eddington phase with rapid variability in X-ray luminosity and spectral parameters, (2) a stable super-Eddington phase at the peak X-ray luminosity, and (3) a steady decline back to the pre-outburst luminosity and spectral parameters. For the first time, we witnessed the formation of the X-ray corona, as the X-ray spectrum transitioned from thermally dominated to primarily Comptonized. We also track the evolution of the prominent, broad 1 keV feature in the early X-ray spectra and show that this feature can be modeled with blueshifted reflection (z = −0.33) from a single-temperature blackbody irradiating spectrum using xillverTDE, a new flavor of the xillver models. Thus, we propose that the 1 keV feature could arise from reflected emission off the base of an optically thick outflow from a geometrically thick, super-Eddington inner accretion flow, connecting the inner accretion flow with outflows launched during extreme accretion events (e.g., tidal disruption events). Lastly, we compare 1ES 1927+654 to other nuclear transients and discuss applications of xillverTDE to super-Eddington accretors.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Masterson, Megan0000-0003-4127-0739
Kara, Erin0000-0003-0172-0854
Ricci, Claudio0000-0001-5231-2645
García, Javier A.0000-0003-3828-2448
Fabian, Andrew C.0000-0002-9378-4072
Pinto, Ciro0000-0003-2532-7379
Kosec, Peter0000-0003-4511-8427
Remillard, Ronald A.0000-0003-4815-0481
Loewenstein, Michael0000-0002-1661-4029
Trakhtenbrot, Benny0000-0002-3683-7297
Arcavi, Iair0000-0001-7090-4898
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 March 9; revised 2022 May 23; accepted 2022 June 6; published 2022 July 22. We thank the anonymous referee for the helpful comments that improved this manuscript. M.M. thanks Ruancun Li, Christos Panagiotou, and Brenna Mockler for their useful comments and discussions. E.K. thanks Daniel Proga and John Raymond for insightful discussions. M.M. and E.K. acknowledge support from NASA grant 80NSSC21K0661. M.M., E.K., B.T., and I.A. acknowledge support from the MISTI Global Seed Funds and the MIT-Israel Zuckerman STEM Fund. C.R. acknowledges support from the Fondecyt Iniciacion grant 11190831 and ANID BASAL project FB210003. R.R. acknowledges support from NASA grant 80NSSC19K1287. I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that program, from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation program (grant agreement No. 852097), from the Israel Science Foundation (grant No. 2752/19), from the United States–Israel Binational Science Foundation (BSF), and from the Israeli Council for Higher Education Alon Fellowship. Facilities: XMM-Newton - , NuSTAR - , NICER. - Software: XSPEC (Arnaud 1996), Astropy (Astropy Collaboration et al. 2013, 2018), xillver (García & Kallman 2010; García et al. 2013), relxill (v1.4.0; García et al. 2014; Dauser et al. 2014).
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Massachusetts Institute of Technology (MIT)UNSPECIFIED
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)11190831
Agencia Nacional de Investigación y Desarrollo (ANID)FB210003
Canadian Institute for Advanced Research (CIFAR)UNSPECIFIED
European Research Council (ERC)852097
Israel Science Foundation2752/19
Binational Science Foundation (USA-Israel)UNSPECIFIED
Israeli Council for Higher EducationUNSPECIFIED
Subject Keywords:Active galactic nuclei; High energy astrophysics; Seyfert galaxies; Supermassive black holes; X-ray transient sources
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Active galactic nuclei (16); High energy astrophysics (739); Seyfert galaxies (1447); Supermassive black holes (1663); X-ray transient sources (1852)
Record Number:CaltechAUTHORS:20220726-998023000
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Official Citation:Megan Masterson et al 2022 ApJ 934 35
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115862
Deposited By: George Porter
Deposited On:27 Jul 2022 20:46
Last Modified:27 Jul 2022 20:46

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