AT 2021loi: A Bowen Fluorescence Flare with a Re-brightening Episode, Occurring in a Previously-Known AGN

by Dr. Lydia Makrygianni

TAU

at Astrophysics and Cosmology Seminar

Wed, 11 Jan 2023, 11:10
Sacta-Rashi Building for Physics (54), room 207

Abstract

AT2021loi is an optical-ultraviolet transient located at the center of its host galaxy. Its spectral features identify it as a member of the “Bowen Fluorescence Flare” (BFF) class. The first member of this class was considered to be related to a tidal disruption event, but enhanced accretion onto an already active supermassive black hole was suggested as an alternative explanation. AT 2021loi, having occurred in a previously-known unobscured AGN, strengthens the latter interpretation. Its light curve is similar to those of previous BFFs, showing a re-brightening approximately one year after the main peak (which was not explicitly identified, but might be the case, in all previous BFFs). An emission feature around 4680A, seen in the pre-flare spectrum, strengthens by a factor of ∼2 around the optical peak of the flare, and is clearly seen as a double peaked feature then, suggesting a blend of NΙΙΙλ4640 with HeΙΙλ4686 as its origin. The appearance of OΙΙΙλ3133 and possible NΙΙΙλλ4097, 4103 (blended with Hδ) during the flare further support a Bowen Fluorescence classification. Ι present ZTF, ATLAS, Keck/LRIS, Las Cumbres Observatory, Swift XRT/UVOT, AMI and VLA observations of AT2021loi, making it one of the best observed BFFs to date. AT2021loi thus provides some clarity on the nature of BFFs but also further demonstrates the diversity of nuclear transients.

Created on 08-01-2023 by Zitrin, Adi (zitrin)
Updaded on 08-01-2023 by Zitrin, Adi (zitrin)