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

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

Research output: Contribution to journalArticlepeer-review

79 Scopus citations


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.

Original languageEnglish
Article number198
JournalAstrophysical Journal
Issue number2
StatePublished - 2019
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved..


We thank the National Radio Astronomy Observatory (NRAO) staff for the rapid scheduling of the VLA observations. NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the staff of the Mullard Radio Astronomy Observatory for their assistance in the operation of AMI. We acknowledge the use of public data from the Swift data archive. This work is based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. Major funding has been provided by the U.S National Science Foundation under grant No. AST-1440341 and by the ZTF partner institutions: the California Institute of Technology, the Oskar Klein Centre, the Weizmann Institute of Science, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron, the University of Wisconsin-Milwaukee, and the TANGO Program of the University System of Taiwan.

FundersFunder number
National Science Foundation1440341, 1616566, 1454816, AST-1440341, 1545949
American Committee for the Weizmann Institute of Science
University of Wisconsin-Milwaukee
University of Washington
University of Maryland
Horizon 2020 Framework Programme759194
European Research Council
Australian Research CouncilFT140101082


    • accretion, accretion disks
    • galaxies: nuclei


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