The First Tidal Disruption Flare in ZTF: From Photometric Selection to Multi-wavelength Characterization

February 2019 • 2019ApJ...872..198V

Authors • van Velzen, Sjoert • Gezari, Suvi • Cenko, S. Bradley • Kara, Erin • Miller-Jones, James C. A. • Hung, Tiara • Bright, Joe • Roth, Nathaniel • Blagorodnova, Nadejda • Huppenkothen, Daniela • Yan, Lin • Ofek, Eran • Sollerman, Jesper • Frederick, Sara • Ward, Charlotte • Graham, Matthew J. • Fender, Rob • Kasliwal, Mansi M. • Canella, Chris • Stein, Robert • Giomi, Matteo • Brinnel, Valery • van Santen, Jakob • Nordin, Jakob • Bellm, Eric C. • Dekany, Richard • Fremling, Christoffer • Golkhou, V. Zach • Kupfer, Thomas • Kulkarni, Shrinivas R. • Laher, Russ R. • Mahabal, Ashish • Masci, Frank J. • Miller, Adam A. • Neill, James D. • Riddle, Reed • Rigault, Mickael • Rusholme, Ben • Soumagnac, Maayane T. • Tachibana, Yutaro

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.


IPAC Authors

Frank Masci

Senior Scientist

Ben Rusholme

Chief Engineer