The awakening beast in the Seyfert 1 Galaxy KUG 1141+371 – I. Issue 1 (3rd December 2020)

• Record Type: Journal Article
• Authors: Jiang, Jiachen; Cheng, Huaqing; Gallo, Luigi C; Ho, Luis C; Buisson, Douglas J K; Fabian, Andrew C; Harrison, Fiona A; Parker, Michael L; Reynolds, Christopher S; Steiner, James F; Tomsick, John A; Walton, Dominic J; Yuan, Weimin
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 501:Issue 1(2021)
• Page Start: 916
• Page End: 932
• Publication Date: 2020-12-03
• Subjects: accretion, accretion discs -- black hole physics -- galaxies: Seyfert -- X-rays: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3737
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: KUG 1141+371 is a Seyfert 1 galaxy that shows a simultaneous flux increase in the optical and UV bands in the past decade. For instance, the latest Swift observation in 2019 shows that the UVW2 flux of the active galactic nucleus in KUG 1141+371 has increased by over one order of magnitude since 2009. Meanwhile, the soft X-ray flux of KUG 1141+371 also shows a steady increase by one order of magnitude since 2007. The significant multiwavelength luminosity change is likely due to a boost of mass accretion rate from approximately $0.6{{\ \rm per\ cent}}$ of the Eddington limit to $3.2{{\ \rm per\ cent}}$, assuming a black hole mass of 10 8 M⊙ . In this work, we conduct detailed multi-epoch X-ray spectral analysis focusing on the variability of the X-ray continuum emission and the puzzling soft excess emission. In addition, our SED models also suggest a simultaneous increase of disc temperature and a decreasing inner disc radius along with the increasing accretion rate. Finally, we discuss possible connection between KUG 1141+371 and black hole transients in outburst.