Constraining the Kilonova Rate with Zwicky Transient Facility Searches Independent of Gravitational Wave and Short Gamma-Ray Burst Triggers

Igor Andreoni, Erik C. Kool, Ana Sagués Carracedo, Mansi M. Kasliwal, Mattia Bulla, Tomás Ahumada, Michael W. Coughlin, Shreya Anand, Jesper Sollerman, Ariel Goobar, David L. Kaplan, Tegan T. Loveridge, Viraj Karambelkar, Jeff Cooke, Ashot Bagdasaryan, Eric C. Bellm, S. Bradley Cenko, David O. Cook, Kishalay De, Richard DekanyAlexandre Delacroix, Andrew Drake, Dmitry A. Duev, Christoffer Fremling, V. Zach Golkhou, Matthew J. Graham, David Hale, S. R. Kulkarni, Thomas Kupfer, Russ R. Laher, Ashish A. Mahabal, Frank J. Masci, Ben Rusholme, Roger M. Smith, Anastasios Tzanidakis, Angela Van Sistine, Yuhan Yao

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The first binary neutron star merger, GW170817, was accompanied by a radioactivity-powered optical/infrared transient called a kilonova. To date, no compelling kilonova has been found in all-sky optical surveys, independently of short gamma-ray burst and gravitational-wave triggers. In this work, we searched the first 23 months of the Zwicky Transient Facility (ZTF) data stream for candidate kilonovae in the form of rapidly evolving transients. We combined ZTF alert queries with forced point-spread-function photometry and nightly flux stacking to increase our sensitivity to faint and fast transients. Automatic queries yielded >11,200 candidates, 24 of which passed quality checks and selection criteria based on a grid of kilonova models tailored for both binary neutron star and neutron star-black hole mergers. None of the candidates in our sample was deemed a possible kilonova after thorough vetting. The sources that passed our selection criteria are dominated by Galactic cataclysmic variables. We identified two fast transients at high Galactic latitude, one of which is the confirmed afterglow of long-duration GRB 190106A, the other is a possible cosmological afterglow. Using a survey simulation code, we constrained the kilonova rate for a range of models including top-hat, linearly decaying light curves, and synthetic light curves obtained with radiative transfer simulations. For prototypical GW170817-like kilonovae, we constrain the rate to be Gpc-3 yr-1 (95% confidence). By assuming a population of kilonovae with the same geometry and composition of GW170817 observed under a uniform viewing angle distribution, we obtained a constraint on the rate of R < 4029 Gpc-3 yr-1.

Original languageEnglish (US)
Article number155
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 1 2020

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© 2020. The American Astronomical Society. All rights reserved..


  • Cataclysmic variable stars (203)
  • Compact objects (288)
  • Gamma-ray bursts (629)
  • Gravitational wave astronomy (675)
  • Gravitational wave sources (677)
  • Neutron stars (1108)
  • Optical bursts (1164)
  • Optical observation (1169)
  • R-process (1324)
  • Surveys (1671)
  • Transient sources (1851)


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