CaltechAUTHORS
Published October 1, 2022 | Version public
Journal Article Metadata-only

Cosmological Fast Optical Transients with the Zwicky Transient Facility: A Search for Dirty Fireballs

Creators

  • 1. ROR icon New York State Office for People With Developmental Disabilities
  • 2. ROR icon University of California, Berkeley
  • 3. ROR icon Lawrence Berkeley National Laboratory
  • 4. ROR icon Cornell University
  • 5. ROR icon Liverpool John Moores University
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Ioffe Institute
  • 8. ROR icon Astrophysique Relativiste, Théories, Expériences, Métrologie, Instrumentation, Signaux
  • 9. ROR icon National Radio Astronomy Observatory
  • 10. ROR icon Instituto de Astrofísica de Andalucía
  • 11. ROR icon Louisiana State University
  • 12. ROR icon University of Maryland, College Park
  • 13. ROR icon University of Washington
  • 14. ROR icon Polytechnic University of Bari
  • 15. ROR icon INFN Sezione di Bari
  • 16. ROR icon University of Alabama in Huntsville
  • 17. ROR icon Indian Institute of Technology Bombay
  • 18. ROR icon Infrared Processing and Analysis Center
  • 19. ROR icon New York University Abu Dhabi
  • 20. ROR icon National Space Science and Technology Center
  • 21. ROR icon Northwestern University
  • 22. ROR icon University of Geneva
  • 23. ROR icon Stockholm University
  • 24. ROR icon Astronomical Institute
  • 25. ROR icon Max Planck Institute for Extraterrestrial Physics

Abstract

Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor Γᵢₙᵢₜ below the Γᵢₙᵢₜ ∼ 100 required to produce a long-duration gamma-ray burst (LGRB), but which could still produce optical emission resembling LGRB afterglows. Here we present the results of a search for on-axis optical afterglows using the Zwicky Transient Facility (ZTF). Our search yielded seven optical transients that resemble on-axis LGRB afterglows in terms of their red colors (g − r > 0 mag), faint host galaxies (r > 23 mag), rapid fading (dr/dt > 1 mag day⁻¹), and in some cases X-ray and radio emission. Spectroscopy of the transient emission within a few days of discovery established cosmological distances (redshift z = 0.876 to 2.9) for six of the seven events, tripling the number of afterglows with redshift measurements discovered by optical surveys without a γ-ray trigger. A likely associated LGRB (GRB 200524A, GRB 210204A, GRB 210212B, and GRB 210610B) was identified for four events (ZTF 20abbiixp/AT 2020kym, ZTF 21aagwbjr/AT 2021buv, ZTF 21aakruew/AT 2021cwd, and ZTF 21abfmpwn/AT 2021qbd) post facto, while three (ZTF 20aajnksq/AT 2020blt, ZTF 21aaeyldq/AT 2021any, and ZTF 21aayokph/AT 2021lfa) had no detected LGRB counterpart. The simplest explanation for the three "orphan" events is that they were regular LGRBs missed by high-energy satellites owing to detector sensitivity and duty cycle, although it is possible that they were intrinsically subluminous in γ-rays or viewed slightly off-axis. We rule out a scenario in which dirty fireballs have a similar energy per solid angle to LGRBs and are an order of magnitude more common. In addition, we set the first direct constraint on the ratio of the opening angles of the material producing γ-rays and the material producing early optical afterglow emission, finding that they must be comparable.

Additional Information

The authors would like to thank WeiKang Zheng at U.C. Berkeley for assistance with Keck observations. A.Y.Q.H. would like to thank Ragnhild Lunnan for helpful comments on the manuscript; and Eliot Quataert, Dan Kasen, Andrew MacFadyen, and Paul Duffell for fruitful discussions about jet structure and dirty fireballs. D.A.P.'s contribution was performed in part at the Aspen Center for Physics, which is supported by National Science Foundation (NSF) grant PHY-1607611. This work was partially supported by a grant from the Simons Foundation. D.F., A.T., and M.U. acknowledge support from RSF grant 21-12-00250. D.A.K. and J.F.A.F acknowledges support from Spanish National Research Project RTI2018-098104-J-I00 (GRBPhot). H.K. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, Brinson and Moore Foundations. J.F.A.F. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades through the grant PRE2018-086507. A.V.F.'s group at U.C. Berkeley is grateful for assistance from the Christopher R. Redlich Fund and many individual donors. 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 NSF under grants AST-1440341 and AST-2034437 and a collaboration including current partners 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, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. 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. SED Machine is based upon work supported by the NSF under grant 1106171. Based on observations obtained at the international Gemini Observatory, a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the NSF on behalf of the Gemini Observatory partnership: the NSF (U.S.), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). Partially based on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. Partially based on observations collected at the Centro Astronómico Hispano en Andalucía (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC). The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by AURA, Inc. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Additional details

Identifiers

Eprint ID
117550
Resolver ID
CaltechAUTHORS:20221024-125854800.19

Related works

Describes
https://resolver.caltech.edu/CaltechAUTHORS:20220224-200924937 (URL)

Funding

NSF
PHY-1607611
Simons Foundation
Russian Science Foundation
21-12-00250
Ministerio de Ciencia e Innovación (MCINN)
RTI2018-098104-J-I00
Large Synoptic Survey Telescope Corporation
NSF
OAC-1829740
Brinson Foundation
Gordon and Betty Moore Foundation
Ministerio de Ciencia, Innovación y Universidades (MICIU)
PRE2018-086507
Christopher R. Redlich Fund
NSF
AST-1440341
NSF
AST-2034437
ZTF partner institutions
Science and Technology Facilities Council (STFC)
NSF
AST-1106171

Dates

Created
2022-11-01
Created from EPrint's datestamp field
Updated
2022-11-01
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility, Division of Geological and Planetary Sciences (GPS)