A new class of transient flares in Super Massive Black Holes

Nada Ihanec , Mariusz Gromadzki, Lukasz Wyrzykowski

The variability of active galactic nuclei in the ultraviolet and optical range is usually at a level of few tens of per cent. Recently, we discovered two transient events located in the centers of galaxies, OGLE17aaj and AT 2017bgt, which showed much more dramatic increase of flux. The optical spectra of these flares exhibit a mix of emission features. Some are typical of luminous, unobscured active galactic nuclei, but others are most likely driven by Bowen fluorescence. The optical spectral features and increased ultraviolet flux show little evolution over a period of at least a year. This disfavors the tidal disruption of a star by the super-massive black hole and other extreme types of active galactic nuclei variability identified in the past. These two objects, together with another similar events, F01004-2237 and Gaia19axp, make a new class of Super Massive Black Hole-related flares.

Proceedings of the Polish Astronomical Society, vol. 10, 226-230 (2020)

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