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Extreme variability in an active galactic nucleus: Gaia16aax

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dc.abstract.enWe present the results of a multiwavelength follow-up campaign for the luminous nuclear transient Gaia16aax, which was first identified in 2016 January. The transient is spatially consistent with the nucleus of an active galaxy at z = 0.25, hosting a black hole of mass ˜ 6× 10^8 M_⊙. The nucleus brightened by more than 1 mag in the Gaia G band over a time-scale of less than 1 yr, before fading back to its pre-outburst state over the following 3 yr. The optical spectra of the source show broad Balmer lines similar to the ones present in a pre-outburst spectrum. During the outburst, the H α and H β 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 disc. We consider variability in the accretion flow in the inner part of the disc, or a tidal disruption event of a star ≥ 1 M_{⊙} 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.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorCannizzaro, G.
dc.contributor.authorFraser, M.
dc.contributor.authorJonker, P. G.
dc.contributor.authorPringle, J. E.
dc.contributor.authorMattila, S.
dc.contributor.authorHewett, P. C.
dc.contributor.authorWevers, T.
dc.contributor.authorKankare, E.
dc.contributor.authorKostrzewa-Rutkowska, Zuzanna
dc.contributor.authorWyrzykowski, Łukasz
dc.contributor.authorOnori, F.
dc.contributor.authorHarmanen, J.
dc.contributor.authorFord, K. E. S.
dc.contributor.authorMcKernan, B.
dc.contributor.authorNixon, C. J.
dc.date.accessioned2024-01-25T00:14:51Z
dc.date.available2024-01-25T00:14:51Z
dc.date.copyright2020-01-21
dc.date.issued2020
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financePublikacja bezkosztowa
dc.description.number1
dc.description.versionORIGINAL_AUTHOR
dc.description.volume493
dc.identifier.doi10.1093/MNRAS/STAA186
dc.identifier.issn0035-8711
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/106891
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2020MNRAS.493..477C
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.relation.pages477-495
dc.rightsOther
dc.sciencecloudnosend
dc.titleExtreme variability in an active galactic nucleus: Gaia16aax
dc.typeJournalArticle
dspace.entity.typePublication