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

van Velzen, Sjoert and Blagorodnova, Nadejda and Graham, Matthew J. and Kasliwal, Mansi M. and Canella, Chris and Fremling, Christoffer and Kupfer, Thomas and Kulkarni, Shrinivas R. and Mahabal, Ashish and Neill, James D. and Yan, Lin and Dekany, Richard and Riddle, Reed and Laher, Russ R. and Masci, Frank J. and Rusholme, Ben and Tachibana, Yutaro (2019) The First Tidal Disruption Flare in ZTF: From Photometric Selection to Multi-wavelength Characterization. Astrophysical Journal, 872 (2). Art. No. 198. ISSN 1538-4357.

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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 0farcs2 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
van Velzen, Sjoert0000-0002-3859-8074
Blagorodnova, Nadejda0000-0003-0901-1606
Graham, Matthew J.0000-0002-3168-0139
Kasliwal, Mansi M.0000-0002-5619-4938
Fremling, Christoffer0000-0002-4223-103X
Kupfer, Thomas0000-0002-6540-1484
Kulkarni, Shrinivas R.0000-0001-5390-8563
Mahabal, Ashish0000-0003-2242-0244
Neill, James D.0000-0002-0466-1119
Yan, Lin0000-0003-1710-9339
Riddle, Reed0000-0002-0387-370X
Laher, Russ R.0000-0003-2451-5482
Masci, Frank J.0000-0002-8532-9395
Rusholme, Ben0000-0001-7648-4142
Tachibana, Yutaro0000-0001-6584-6945
Additional Information:© 2019 The American Astronomical Society. Received 2018 September 7; revised 2018 December 21; accepted 2019 January 5; published 2019 February 25. We thank the referee for the useful comments. 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. 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 research made use of Astropy, a community-developed core Python package for Astronomy (The Astropy Collaboration et al. 2018). S. Gezari is supported in part by NSF CAREER grant 1454816 and NSF AAG grant 1616566. M. M. Kasliwal acknowledges support by the GROWTH (Global Relay of Observatories Watching Transients Happen) project funded by the National Science Foundation PIRE (Partnership in International Research and Education) program under Grant No 1545949. N.R. acknowledges the support of a Joint Space-Science Institute prize postdoctoral fellowship. J.C.A.M.-J. is supported by an Australian Research Council Future Fellowship (FT140101082). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 759194—USNAC). Software: Astropy (The Astropy Collaboration et al. 2018), CASA (McMullin et al. 2007), HEAsoft (Arnaud 1996), SAS (Gabriel et al. 2004), FSPS (Conroy et al. 2009; Conroy & Gunn 2010) with Python binding from Foreman-Mackey et al. 2014).
Group:Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
Oskar Klein CentreUNSPECIFIED
Weizmann Institute of ScienceUNSPECIFIED
University of Maryland UNSPECIFIED
University of WashingtonUNSPECIFIED
Deutsches Elektronen-SynchrotronUNSPECIFIED
University of Wisconsin-MilwaukeeUNSPECIFIED
University System of TaiwanUNSPECIFIED
Associated Universities, Inc.UNSPECIFIED
Joint Space-Science InstituteUNSPECIFIED
Australian Research CouncilFT140101082
European Research Council (ERC)759194
Record Number:CaltechAUTHORS:20190225-095722804
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Official Citation:Sjoert van Velzen et al 2019 ApJ 872 198
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93218
Deposited By: Tony Diaz
Deposited On:25 Feb 2019 18:12
Last Modified:28 Apr 2019 16:39

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