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Published October 2018 | Published + Accepted Version
Journal Article Open

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

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.

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.

Attached Files

Published - Hung_2018_ApJS_238_15.pdf

Accepted Version - 1712.04936.pdf

Accepted Version - nihms-1527449.pdf

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Additional details

Created:
August 19, 2023
Modified:
October 18, 2023