Extreme variability in an active galactic nucleus: Gaia16aax
| Autor: | Jussi Harmanen, Łukasz Wyrzykowski, Paul C. Hewett, J. E. Pringle, Peter G. Jonker, Thomas Wevers, Chris Nixon, Z. Kostrzewa-Rutkowska, Giacomo Cannizzaro, Francesca Onori, Seppo Mattila, Erkki Kankare, Morgan Fraser, Barry McKernan, K. E. S. Ford |
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| Rok vydání: | 2020 |
| Předmět: |
Active galactic nucleus
Stellar mass Astronomy Astrophysics::High Energy Astrophysical Phenomena FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Tidal disruption event 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics High Energy Physics 010306 general physics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Physics High Energy Astrophysical Phenomena (astro-ph.HE) Supermassive black hole Astronomy and Astrophysics Quasar Light curve Astrophysics - Astrophysics of Galaxies Black hole Neutron star 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Astrophysics::Earth and Planetary Astrophysics Astrophysics - High Energy Astrophysical Phenomena |
| Zdroj: | BASE-Bielefeld Academic Search Engine Monthly Notices of the Royal Astronomical Society, 493, 1, pp. 477-495 Monthly Notices of the Royal Astronomical Society Monthly Notices of the Royal Astronomical Society, 493(1), 477-495 Monthly Notices of the Royal Astronomical Society, 493, 477-495 |
| ISSN: | 0035-8711 |
| Popis: | We present the results of a multi-wavelength follow up campaign for the luminous nuclear transient Gaia16aax, which was first identified in January 2016. The transient is spatially consistent with the nucleus of an active galaxy at z=0.25, hosting a black hole of mass $\rm \sim6\times10^8M_\odot$. The nucleus brightened by more than 1 magnitude in the Gaia G-band over a timescale of less than one year, before fading back to its pre-outburst state over the following three years. The optical spectra of the source show broad Balmer lines similar to the ones present in a pre-outburst spectrum. During the outburst, the $\rm H\alpha$ and $\rm H\beta$ emission lines develop a secondary peak. We also report on the discovery of two transients with similar light curve evolution and spectra: Gaia16aka and Gaia16ajq. We consider possible scenarios to explain the observed outbursts. We exclude that the transient event could be caused by a microlensing event, variable dust absorption or a tidal encounter between a neutron star and a stellar mass black hole in the accretion disk. We consider variability in the accretion flow in the inner part of the disk, or a tidal disruption event of a star $\geq 1 M_{\odot}$ by a rapidly spinning supermassive black hole as the most plausible scenarios. We note that the similarity between the light curves of the three Gaia transients may be a function of the Gaia alerts selection criteria. Comment: 21 pages, 17 figure - accepted for publication in MNRAS main journal |
| Databáze: | OpenAIRE |
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