The First Tidal Disruption Flare in ZTF: From Photometric Selection to Multi-wavelength Characterization
/ Authors
S. van Velzen, S. Gezari, S. Cenko, E. Kara, J. Miller-Jones, T. Hung, J. Bright, Nathaniel Roth, N. Blagorodnova, D. Huppenkothen
and 30 more authors
Lin Yan, E. Ofek, J. Sollerman, S. Frederick, C. Ward, M. Graham, R. Fender, M. Kasliwal, Chris Canella, R. Stein, M. Giomi, V. Brinnel, J. Santen, J. Nordin, E. Bellm, R. Dekany, C. Fremling, V. Golkhou, T. Kupfer, S. Kulkarni, R. Laher, A. Mahabal, F. Masci, Adam A. Miller, James D. Neill, R. Riddle, M. Rigault, B. Rusholme, M. Soumagnac, Yutaro 朗橘 Tachibana 優太
/ Abstract
We present Zwicky Transient Facility (ZTF) observations of the tidal disruption flare AT2018zr/PS18kh reported by Holoien et al. and detected during ZTF commissioning. The ZTF light curve of the tidal disruption event (TDE) samples the rise-to-peak exceptionally well, with 50 days of g- and r-band detections before the time of maximum light. We also present our multi-wavelength follow-up observations, including the detection of a thermal (kT ≈ 100 eV) X-ray source that is two orders of magnitude fainter than the contemporaneous optical/UV blackbody luminosity, and a stringent upper limit to the radio emission. We use observations of 128 known active galactic nuclei (AGNs) to assess the quality of the ZTF astrometry, finding a median host-flare distance of 0.″2 for genuine nuclear flares. Using ZTF observations of variability from known AGNs and supernovae we show how these sources can be separated from TDEs. A combination of light-curve shape, color, and location in the host galaxy can be used to select a clean TDE sample from multi-band optical surveys such as ZTF or the Large Synoptic Survey Telescope.
Journal: The Astrophysical Journal