We present a nuclear transient event, PS1-13cbe, that was first discovered in the Pan-STARRS1 survey in 2013. The outburst occurred in the nucleus of the galaxy SDSS J222153.87+003054.2 at z=0.12355, which was classified as a Seyfert 2 in a pre-outburst archival Sloan Digital Sky Survey (SDSS) spectrum. PS1-13cbe showed the appearance of strong broad Hα and Hβ emission lines and a non-stellar continuum in a Magellan spectrum taken 57 days after the peak of the outburst that resembled the characteristics of a Seyfert 1. These broad lines were not present in the SDSS spectrum taken a decade earlier and faded away within two years, as observed in several late-time MDM spectra. We argue that the dramatic appearance and disappearance of the broad lines and factor of ∼8 increase in the optical continuum is most likely caused by variability in the pre-existing accretion disk than a tidal disruption event, supernova, or variable obscuration. The timescale for the turn-on of the optical emission of ∼70 days observed in this transient is among the shortest observed in a "changing look" active galactic nucleus.
@article{arxiv.1811.03694,
title = {PS1-13cbe: The Rapid "Turn on" of a Seyfert 1},
author = {Reza Katebi and Ryan Chornock and Edo Berger and David O. Jones and Ragnhild Lunnan and Raffaella Margutti and Armin Rest and Daniel M. Scolnic and William S. Burgett and Nick Kaiser and Rolf-Peter Kudritzki and Eugene A. Magnier and Richard J. Wainscoat and Christopher Waters},
journal= {arXiv preprint arXiv:1811.03694},
year = {2018}
}