An X-ray flaring event and a variable soft X-ray excess in the Seyfert LCRS B040659.9–385922 as detected with eROSITA
Rattachement africain : pl, in, us, de, jp, Afrique du Sud. Niveau de preuve : code pays fourni par la source.
Le résumé fourni par la source
Context. Extreme continuum variability in extragalactic nuclear sources can indicate extreme changes in accretion flows onto supermassive black holes. Aims. We explore the multiwavelength nature of a continuum flare in the Seyfert LCRS B040659.9−385922. The all-sky X-ray surveys conducted by the Spectrum Roentgen Gamma (SRG)/extended ROentgen Survey with an Imaging Telescope Array (eROSITA) showed that its X-ray flux increased by a factor of roughly five over six months, and concurrent optical photometric monitoring with the Asteroid Terrestrial-impact Last Alert System (ATLAS) showed a simultaneous increase. Methods. We complemented the eROSITA and ATLAS data by triggering a multiwavelength follow-up monitoring program (X-ray Multi-Mirror Mission: XMM-Newton, Neutron star Interior Composition Explorer: NICER; optical spectroscopy) to study the evolution of the accretion disk, broad-line region, and X-ray corona. During the campaign, X-ray and optical continuum flux subsided over roughly six months. Our campaign includes two XMM-Newton observations, one taken near the peak of this flare and the other taken when the flare had subsided. Results. The soft X-ray excess in both XMM-Newton observations was power law-like (distinctly nonthermal). Using a simple power law, we observed that the photon index of the soft excess varies from a steep value of Γ ∼ 2.7 at the flare peak to a relatively flatter value of Γ ∼ 2.2 as the flare subsided. We successfully modeled the broadband optical/UV/X-ray spectral energy distribution at both the flare peak and post-flare times with the AGNSED model, incorporating thermal disk emission into the optical/UV and warm thermal Comptonization in the soft X-rays. The accretion rate falls by roughly 2.5, and the radius of the hot Comptonizing region increases from the flaring state to the post-flare state. Additionally, from the optical spectral observations, we find that the broad He IIλ4686 emission line fades significantly as the optical/UV/X-ray continuum fades, which could indicate a substantial flare of disk emission above 54 eV. We also observed a redshifted broad component in the Hβ emission line that is present during the high flux state of the source and disappears in subsequent observations. Conclusions. A sudden strong increase in the local accretion rate in this source manifested itself via an increase in accretion disk emission and in thermal Comptonized emission in the soft X-rays, which subsequently faded. The redshifted broad Balmer component could be associated with a transient kinematic component distinct from that comprising the rest of the broad-line region.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- An X-ray flaring event and a variable soft X-ray excess in the Seyfert LCRS B040659.9–385922 as detected with eROSITA
- Date Crossref
- 31/10/2024
- Éditeur
- EDP Sciences
- Type
- journal-article
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Nicolaus Copernicus Astronomical Center pays non établi dans la noticeStructure de recherche
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Inter-University Centre for Astronomy and Astrophysics 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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University of California San Diego pays non établi dans la noticeUniversité ou école supérieure
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Leibniz Institute for Astrophysics Potsdam pays non établi dans la noticeStructure de recherche
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Friedrich-Alexander-Universität Erlangen-Nürnberg pays non établi dans la noticeUniversité ou école supérieure
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University of Warsaw Astronomical Observatory pays non établi dans la noticeUniversité ou école supérieure
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Saitama University pays non établi dans la noticeUniversité ou école supérieure
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University of North Carolina at Chapel Hill Department of Physics and Astronomy 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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Max Planck Institute for Extraterrestrial Physics pays non établi dans la noticeStructure de recherche
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Leibniz-Institut für Astrophysik Potsdam pays non établi dans la noticeStructure de recherche
Nicolaus Copernicus Astronomical Center, Inter-University Centre for Astronomy and Astrophysics et Nicolaus Copernicus Astronomical Center — Polish Academy of Sciences, avec 9 autres affiliations. Pays d’affiliation : Afrique du Sud.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.