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Sifting for Sapphires: Systematic Selection of Tidal Disruption Events in iPTF

Hung, T. and Gezari, S. and Cenko, S. B. and van Velzen, S. and Blagorodnova, N. and Yan, Lin and Kulkarni, S. R. and Lunnan, R. and Kupfer, T. and Leloudas, G. and Kong, A. K. H. and Nugent, P. E. and Fremling, C. and Laher, Russ R. and Masci, F. J. and Cao, Y. and Roy, R. and Petrushevska, T. (2018) Sifting for Sapphires: Systematic Selection of Tidal Disruption Events in iPTF. Astrophysical Journal Supplement Series, 238 (2). Art. No. 15. ISSN 1538-4365. https://resolver.caltech.edu/CaltechAUTHORS:20180927-161113513

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Abstract

We present results from a systematic selection of tidal disruption events (TDEs) in a wide-area (4800 deg^2), g+R band, Intermediate Palomar Transient Factory experiment. Our selection targets typical optically selected TDEs: bright (>60% flux increase) and blue transients residing in the centers of red galaxies. Using photometric selection criteria to down-select from a total of 493 nuclear transients to a sample of 26 sources, we then use follow-up UV imaging with the Neil Gehrels Swift Telescope, ground-based optical spectroscopy, and light curve fitting to classify them as 14 Type Ia supernovae (SNe Ia), 9 highly variable active galactic nuclei (AGNs), 2 confirmed TDEs, and 1 potential core-collapse supernova. We find it possible to filter AGNs by employing a more stringent transient color cut (g − r < −0.2 mag); further, UV imaging is the best discriminator for filtering SNe, since SNe Ia can appear as blue, optically, as TDEs in their early phases. However, when UV-optical color is unavailable, higher-precision astrometry can also effectively reduce SNe contamination in the optical. Our most stringent optical photometric selection criteria yields a 4.5:1 contamination rate, allowing for a manageable number of TDE candidates for complete spectroscopic follow-up and real-time classification in the Zwicky Transient Facility era. We measure a TDE per galaxy rate of 1.7^(+2.9)_(-1.3) x 10^(-4) gal^(-1) yr^(-1) (90% CL in Poisson statistics). This does not account for TDEs outside our selection criteria, and thus may not reflect the total TDE population, which is yet to be fully mapped.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4365/aad8b1DOIArticle
https://arxiv.org/abs/1712.04936arXivDiscussion Paper
ORCID:
AuthorORCID
Hung, T.0000-0002-9878-7889
Gezari, S.0000-0003-3703-5154
Cenko, S. B.0000-0003-1673-970X
van Velzen, S.0000-0002-3859-8074
Blagorodnova, N.0000-0003-0901-1606
Yan, Lin0000-0003-1710-9339
Kulkarni, S. R.0000-0001-5390-8563
Lunnan, R.0000-0001-9454-4639
Kupfer, T.0000-0002-6540-1484
Leloudas, G.0000-0002-8597-0756
Kong, A. K. H.0000-0002-5105-344X
Nugent, P. E.0000-0002-3389-0586
Fremling, C.0000-0002-4223-103X
Laher, Russ R.0000-0003-2451-5482
Masci, F. J.0000-0002-8532-9395
Cao, Y.0000-0002-8036-8491
Petrushevska, T.0000-0003-4743-1679
Additional Information:© 2018 The American Astronomical Society. Received 2017 December 8; revised 2018 July 20; accepted 2018 August 4; published 2018 September 27. We thank the anonymous referee for helpful comments that improved the manuscript. T.H. thanks Jesper Sollerman for his feedback on the manuscript. S.G. is supported in part by NASA Swift Cycle 12 grant NNX16AN85G and NSF CAREER grant 1454816. 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 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. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DEAC02-05CH11231.
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory
Funders:
Funding AgencyGrant Number
NASANNX16AN85G
NSFAST-1454816
W. M. Keck FoundationUNSPECIFIED
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:accretion, accretion disks – black hole physics – galaxies: nuclei – surveys – ultraviolet: general
Issue or Number:2
Record Number:CaltechAUTHORS:20180927-161113513
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180927-161113513
Official Citation:T. Hung et al 2018 ApJS 238 15
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90042
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Sep 2018 23:41
Last Modified:03 Oct 2019 20:21

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