| Name: | Saikruba Krishnan |
| Affiliation: | The Inter-University Centre for Astronomy and Astrophysics (IUCAA) |
| Conference ID : | ASI2024_433 |
| Title : | Multi-wavelength study of an X-ray flaring event and a variable soft X-ray excess in Seyfert galaxy detected with eROSITA |
| Authors : | S. Krishnan1⋆, A.G. Markowitz1, 2, M. Krumpe3, D. Homan3, R. Brogan3, S. Haemmerich4, M. Gromadzki5, T. Saha1, M. Schramm6, H. Winkler7, S. Waddell8, J. Wilms4, A. Rau8, Z. Liu8, and I. Grotova8 |
| Authors Affiliation: | 1. Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warszawa, Poland
2. University of California, San Diego, Center for Astrophysics and Space Sciences, MC 0424, La Jolla, CA, 92093-0424, USA
3. Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
4. Remeis Observatory & Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwart-str. 7, 96049 Bamberg, Germany
5. Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, PL-00-478 Warsaw, Poland
6. Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
7. Department of Physics, University of Johannesburg, Kingsway, Auckland Park, Johannesburg, 2006, South Africa
8. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching bei München, Germany |
| Mode of Presentation: | Poster |
| Abstract Category : | High Energy Phenomena, Fundamental Physics and Astronomy |
| Abstract : | Active Galactic Nuclei (AGN) are powered by accretion of gas onto supermassive black holes. There are open questions regarding how the X-ray corona, disk, and BLR evolve in response to changes in the global accretion supply. We are using eROSITA's all-sky X-ray surveys to identify extragalactic X-ray transients. I present multi-wavelength observations of a candidate AGN transient event detected with eROSITA. Its X-ray flux increased by ~6 over six months; concurrent optical photometric monitoring data with ATLAS showed a simultaneous increase by 4. We triggered a multi-wavelength follow-up monitoring program (XMM-Newton, NICER; optical spectroscopy) to study the evolution of the accretion disk, broad-line region, and X-ray corona. We witnessed a likely sudden strong increase in local accretion rate, which manifested itself via an increase in accretion disk emission and thermal Comptonization emission in the soft X-rays, followed by a decrease in accretion and Comptonized luminosity. The physical processes (e.g., disk instabilities) leading to such substantial variations are still an open question, and future continuous monitoring along with multi-wavelength studies will shed some light on it. |
