TY - JOUR
T1 - Fast-transient searches in real time with ZTFReST: Identification of three optically discovered gamma-ray burst afterglows and new constraints on the kilonova rate
AU - Andreoni, Igor
AU - Coughlin, Michael W.
AU - Kool, Erik C.
AU - Kasliwal, Mansi M.
AU - Kumar, Harsh
AU - Bhalerao, Varun
AU - Carracedo, Ana Sagués
AU - Ho, Anna Y.Q.
AU - Pang, Peter T.H.
AU - Saraogi, Divita
AU - Sharma, Kritti
AU - Shenoy, Vedant
AU - Burns, Eric
AU - Ahumada, Tomás
AU - Anand, Shreya
AU - Singer, Leo P.
AU - Perley, Daniel A.
AU - De, Kishalay
AU - Fremling, U. C.
AU - Bellm, Eric C.
AU - Bulla, Mattia
AU - Crellin-Quick, Arien
AU - Dietrich, Tim
AU - Drake, Andrew
AU - Duev, Dmitry A.
AU - Goobar, Ariel
AU - Graham, Matthew J.
AU - Kaplan, David L.
AU - Kulkarni, S. R.
AU - Laher, Russ R.
AU - Mahabal, Ashish A.
AU - Shupe, David L.
AU - Sollerman, Jesper
AU - Walters, Richard
AU - Yao, Yuhan
N1 - Funding Information:
M.W.C acknowledges support from the National Science Foundation with grant number PHY-2010970. M.B. acknowledges support from the Swedish Research Council (Reg. no. 2020-03330). A.S.C, E.C.K., A.G., and J.S., acknowledge support from the G.R.E.A.T. research environment funded by Vetenskapsr?det, the Swedish Research Council, under project number 2016-06012, and support from The Wenner-Gren Foundations. Bayes factor computations between kilonova and GRB afterglow models have used computational resources provided through SuperMUC_NG (LRZ) under project number pn29ba and Hawk (HLRS) under project number 44189. This work was supported by the GROWTH project funded by the National Science Foundation under PIRE grant No. 1545949. GROWTH is a collaborative project among California Institute of Technology (USA), University of Maryland College Park (USA), University of Wisconsin Milwaukee (USA), Texas Tech University (USA), San Diego State University (USA), University of Washington (USA), Los Alamos National Laboratory (USA), Tokyo Institute of Technology (Japan), National Central University (Taiwan), Indian Institute of Astrophysics (India), Indian Institute of Technology Bombay (India), Weizmann Institute of Science (Israel), The Oskar Klein Centre at Stockholm University (Sweden), Humboldt University (Germany), Liverpool John Moores University (UK), and University of Sydney (Australia). 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-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant No. 12540303 (PI: Graham). 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. This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. The ATLAS project is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queens University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile.
Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/9/8
Y1 - 2021/9/8
N2 - The most common way to discover extragalactic fast transients, which fade within a few nights in the optical, is via follow-up of gamma-ray burst and gravitational-wave triggers. However, wide-field surveys have the potential to identify rapidly fading transients independently of such external triggers. The volumetric survey speed of the Zwicky Transient Facility (ZTF) makes it sensitive to objects as faint and fast fading as kilonovae, the optical counterparts to binary neutron star mergers, out to almost 200 Mpc. We introduce an open-source software infrastructure, the ZTF REaltime Search and Triggering, ZTFReST, designed to identify kilonovae and fast transients in ZTF data. Using the ZTF alert stream combined with forced point-spread-function photometry, we have implemented automated candidate ranking based on their photometric evolution and fitting to kilonova models. Automated triggering, with a human in the loop for monitoring, of follow-up systems has also been implemented. In 13 months of science validation, we found several extragalactic fast transients independently of any external trigger, including two supernovae with post-shock cooling emission, two known afterglows with an associated gamma-ray burst (ZTF20abbiixp, ZTF20abwysqy), two known afterglows without any known gamma-ray counterpart (ZTF20aajnksq, ZTF21aaeyldq), and three new fast-declining sources (ZTF20abtxwfx, ZTF20acozryr, ZTF21aagwbjr) that are likely associated with GRB200817A, GRB201103B, and GRB210204A. However, we have not found any objects that appear to be kilonovae. We constrain the rate of GW170817-like kilonovae to R < 900 Gpc-3 yr-1 (95% confidence). A framework such as ZTFReST could become a prime tool for kilonova and fast-transient discovery with the Vera Rubin Observatory.
AB - The most common way to discover extragalactic fast transients, which fade within a few nights in the optical, is via follow-up of gamma-ray burst and gravitational-wave triggers. However, wide-field surveys have the potential to identify rapidly fading transients independently of such external triggers. The volumetric survey speed of the Zwicky Transient Facility (ZTF) makes it sensitive to objects as faint and fast fading as kilonovae, the optical counterparts to binary neutron star mergers, out to almost 200 Mpc. We introduce an open-source software infrastructure, the ZTF REaltime Search and Triggering, ZTFReST, designed to identify kilonovae and fast transients in ZTF data. Using the ZTF alert stream combined with forced point-spread-function photometry, we have implemented automated candidate ranking based on their photometric evolution and fitting to kilonova models. Automated triggering, with a human in the loop for monitoring, of follow-up systems has also been implemented. In 13 months of science validation, we found several extragalactic fast transients independently of any external trigger, including two supernovae with post-shock cooling emission, two known afterglows with an associated gamma-ray burst (ZTF20abbiixp, ZTF20abwysqy), two known afterglows without any known gamma-ray counterpart (ZTF20aajnksq, ZTF21aaeyldq), and three new fast-declining sources (ZTF20abtxwfx, ZTF20acozryr, ZTF21aagwbjr) that are likely associated with GRB200817A, GRB201103B, and GRB210204A. However, we have not found any objects that appear to be kilonovae. We constrain the rate of GW170817-like kilonovae to R < 900 Gpc-3 yr-1 (95% confidence). A framework such as ZTFReST could become a prime tool for kilonova and fast-transient discovery with the Vera Rubin Observatory.
UR - http://www.scopus.com/inward/record.url?scp=85115962408&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/ac0bc7
DO - 10.3847/1538-4357/ac0bc7
M3 - Article
AN - SCOPUS:85115962408
SN - 0004-637X
VL - 918
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 63
ER -