A Changing-Look Seyfert Discovered by eROSITA Reveals a Two-Component Broad-Line Region
Rattachement africain : pl, de, gb, ru, rs, Afrique du Sud, in, us. Niveau de preuve : code pays fourni par la source.
Le résumé fourni par la source
Extreme sudden changes in the flow of accreting gas onto SMBHs manifest themselves via large-amplitude continuum variability and changes to broad Balmer emission profiles, driving changing-look AGN. X-ray flux monitoring with SRG/eROSITA revealed that in the Seyfert AGN HE 1237-2252 the soft X-ray flux dipped abruptly, by a factor of 17 within 18 months. We initiated a follow-up campaign that caught the luminosity recovery after the dip, and enabled us to study how the various accretion components responded during this flux recovery. Our campaign included multiband photometry, X-ray spectroscopy, and optical spectroscopy. We tracked as the accretion rate relative to Eddington increased by a factor of 7 in 3 years. Based on broad Hbeta variability, HE 1237-2252 was subtype 1.0-1.2 in 2002, transitioned to subtype 1.8 by the time of the luminosity dip, and then transitioned back to subtype 1.0 within 3 months as luminosity recovered. Both transitions saw broad Hbeta integrated line flux change by factors of 4-6. The broad Balmer profile is decomposed into a broad Gaussian consistent with virialized gas at 27+/-3 lt-dy, plus a double-peaked profile, consistent with a diskline structure at more than roughly 5 lt-dy. The diskline component's relative contribution to the total profile increases as continuum flux rises. The lack of obscuration in the X-ray spectra, as well as the IR continuum dip, point to an intrinsic pause in the accretion rate as opposed to variable line-of-sight obscuration. Candidates for the underlying mechanisms include propagating cold and warm fronts in the accretion disk. The increased prominence of the diskline BLR component's emission could be due to evolution in the physical extent of the X-ray corona, and in the fraction of >13.6 eV photons intercepted by the diskline, as the accretion rate increases.
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Nicolaus Copernicus Astronomical Center pays non établi dans la noticeStructure de recherche
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Polish Academy of Sciences Nicolaus Copernicus Astronomical Center pays non établi dans la noticeOrganisme public
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Leibniz Institute for Astrophysics Potsdam pays non établi dans la noticeStructure de recherche
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University of Cambridge Institute of Astronomy pays non établi dans la noticeUniversité ou école supérieure
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Institute of Astronomy pays non établi dans la noticeStructure de recherche
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Center for Theoretical Physics pays non établi dans la noticeStructure de recherche
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Astronomical Observatory Afrique du Sud (pays nommé en fin d’affiliation)Structure de recherche
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University of Warsaw Astronomical Observatory pays non établi dans la noticeUniversité ou école supérieure
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University of Johannesburg Department of Physics University of Johannesburg, Afrique du Sud (code pays fourni par la source)Université ou école supérieure
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Friedrich-Alexander-Universität Erlangen-Nürnberg pays non établi dans la noticeUniversité ou école supérieure
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Inter-University Centre for Astronomy and Astrophysics pays non établi dans la noticeStructure de recherche
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University of the Free State Department of Physics Afrique du Sud (code pays fourni par la source)Université ou école supérieure
Nicolaus Copernicus Astronomical Center, Nicolaus Copernicus Astronomical Center — Polish Academy of Sciences et Leibniz Institute for Astrophysics Potsdam, avec 9 autres affiliations. Pays d’affiliation : Afrique du Sud.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.