We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the OGLE-IV survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5 mag, slow decline, very broad He and H spectral features make OGLE16aaa similar to other optical/UV Tidal Disruption Events (TDEs). Weak narrow emission lines in the spectrum and archival photometric observations suggest the host galaxy is a weak-line Active Galactic Nucleus (AGN), which has been accreting at higher rate in the past. OGLE16aaa, along with SDSS J0748, seems to form a sub-class of TDEs by weakly or recently active super-massive black holes (SMBHs). This class might bridge the TDEs by quiescent SMBHs and flares observed as "changing-look QSOs", if we interpret the latter as TDEs. If this picture is true, the previously applied requirement for identifying a flare as a TDE that it had to come from an inactive nucleus, could be leading to observational bias in TDE selection, thus affecting TDE-rate estimations.
@article{arxiv.1606.03125,
title = {OGLE16aaa - a Signature of a Hungry Super Massive Black Hole},
author = {Łukasz Wyrzykowski and M. Zieliński and Z. Kostrzewa-Rutkowska and A. Hamanowicz and P. G. Jonker and I. Arcavi and J. Guillochon and P. J. Brown and S. Kozłowski and A. Udalski and M. K. Szymański and I. Soszyński and R. Poleski and P. Pietrukowicz and J. Skowron and P. Mróz and K. Ulaczyk and M. Pawlak and K. A. Rybicki and J. Greiner and T. Krühler and J. Bolmer and S. J. Smartt and K. Maguire and K. Smith},
journal= {arXiv preprint arXiv:1606.03125},
year = {2016}
}