A Caltech Library Service

Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies

van Velzen, Sjoert and Gezari, Suvi and Hammerstein, Erica and Roth, Nathaniel and Frederick, Sara and Ward, Charlotte and Hung, Tiara and Cenko, S. Bradley and Stein, Robert and Perley, Daniel A. and Taggart, Kirsty and Sollerman, Jesper and Andreoni, Igor and Bellm, Eric C. and Brinnel, Valery and De, Kishalay and Dekany, Richard and Feeney, Michael and Foley, Ryan J. and Fremling, Christoffer and Giomi, Matteo and Golkhou, V. Zach and Ho, Anna Y. Q. and Kasliwal, Mansi M. and Kilpatrick, Charles D. and Kulkarni, Shrinivas R. and Kupfer, Thomas and Laher, Russ R. and Mahabal, Ashish and Masci, Frank J. and Nordin, Jakob and Riddle, Reed and Rusholme, Ben and Sharma, Yashvi and van Santen, Jakob and Shupe, David L. and Soumagnac, Maayane T. (2020) Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies. . (Unpublished)

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


While tidal disruption events (TDEs) have long been heralded as laboratories for the study of quiescent black holes, the small number of known TDEs and uncertainties in their emission mechanism have hindered progress towards this promise. Here present 17 new TDEs that have been detected recently by the Zwicky Transient Facility along with Swift UV and X-ray follow-up observations. Our homogeneous analysis of the optical/UV light curves, including 22 previously known TDEs from the literature, reveals a clean separation of light curve properties with spectroscopic class. The TDEs with Bowen fluorescence features in their optical spectra have smaller blackbody radii, as well as longer rise times and higher disruption rates compared to the rest of the sample. The Bowen fluorescence mechanism requires a high density which can be reached at smaller radii, which in turn yields longer diffusion timescales. Thus, the difference in rise times suggests the pre-peak TDE light curves are governed not by the fallback timescale, but instead by the diffusion of photons through the tidal debris. The small subset of TDEs that show only helium emission lines in their spectra have the longest rise times, the highest luminosities and the lowest rates. We also report, for the first time, the detection of soft X-ray flares from a TDE on day timescales. Based on the fact the flares peak at a luminosity similar to the optical/UV blackbody luminosity, we attribute them to brief glimpses through a reprocessing layer that otherwise obscures the inner accretion flow.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
van Velzen, Sjoert0000-0002-3859-8074
Andreoni, Igor0000-0002-8977-1498
De, Kishalay0000-0002-8989-0542
Dekany, Richard0000-0002-5884-7867
Fremling, Christoffer0000-0002-4223-103X
Ho, Anna Y. Q.0000-0002-9017-3567
Kasliwal, Mansi M.0000-0002-5619-4938
Kulkarni, Shrinivas R.0000-0001-5390-8563
Laher, Russ R.0000-0003-2451-5482
Mahabal, Ashish0000-0003-2242-0244
Masci, Frank J.0000-0002-8532-9395
Riddle, Reed0000-0002-0387-370X
Rusholme, Ben0000-0001-7648-4142
Shupe, David L.0000-0003-4401-0430
Additional Information: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. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171. These results made use of the Discovery Channel Telescope at Lowell Observatory. Lowell is a private, non-profit institution dedicated to astrophysical research and public appreciation of astronomy and operates the DCT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University and Yale University. The upgrade of the DeVeny optical spectrograph has been funded by a generous grant from John and Ginger Giovale. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; the Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Research at Lick Observatory is partially supported by a generous gift from Google. We thank the Swift team, including the Observation Duty Scientists, and the science planners for promptly approving and executing our Swift observations. We also acknowledge the use of public data from the Swift data archive. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. We thank J. Brown and M. Siebert for help with Keck observations. S. van Velzen is supported by the James Arhtur Fellowship. S. Gezari is supported in part by NSF CAREER grant 1454816 and NSF AAG grant 1616566. N.R. acknowledges the support of a Joint Space-Science Institute prize postdoctoral fellowship. 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). A.Y.Q.H. is supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE1144469. This work was supported by the GROWTH project funded by the National Science Foundation under PIRE Grant No. 1545949. C. Fremling gratefully acknowledges support of his research by the Heising-Simons Foundation (#2018-0907). The UCSC transient team is supported in part by NSF grant AST-1518052, NASA/Swift grant 80NSSC19K1386, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, and by a fellowship from the David and Lucile Packard Foundation to R.J.F. Software: Ampel (Nordin et al. 2019), Astropy (Astropy Collaboration et al. 2018), catsHTM(Soumagnac & Ofek 2018b),emcee(Foreman-Mackey et al. 2013), extcats (, gPhoton (Million et al. 2016), HEAsoft (Arnaud 1996), FSPS (Conroy et al. 2009; Conroy & Gunn 2010;Foreman-Mackey et al. 2014), Prospector (Johnson & Leja 2017).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
Infrared Processing and Analysis Center (IPAC)UNSPECIFIED
Weizmann Institute of ScienceUNSPECIFIED
Stockholm UniversityUNSPECIFIED
University of MarylandUNSPECIFIED
University of WashingtonUNSPECIFIED
Deutsches Elektronen-SynchrotronUNSPECIFIED
Humboldt UniversityUNSPECIFIED
Los Alamos National LaboratoryUNSPECIFIED
University of Wisconsin-MilwaukeeUNSPECIFIED
Lawrence Berkeley National LaboratoryUNSPECIFIED
John and Ginger GiovaleUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
James Arthur FellowshipUNSPECIFIED
Joint Space-Science InstituteUNSPECIFIED
European Research Council (ERC)759194
NSF Graduate Research FellowshipDGE-1144469
Heising-Simons Foundation2018-0907
Gordon and Betty Moore FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20200414-075012273
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102520
Deposited By: Tony Diaz
Deposited On:14 Apr 2020 16:09
Last Modified:14 Apr 2020 16:09

Repository Staff Only: item control page