Low-efficiency long gamma-ray bursts: a case study with AT2020blt

N. Sarin, R. Hamburg, E. Burns, G. Ashton, P. D. Lasky, G. P. Lamb

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8 Citations (Scopus)

Abstract

The Zwicky Transient Facility recently announced the detection of an optical transient AT2020blt at redshift z = 2.9, consistent with the afterglow of an on-axis gamma-ray burst. However, no prompt emission was observed. We analyse AT2020blt with detailed models, showing the data are best explained as the afterglow of an on-axis long gamma-ray burst, ruling out other hypotheses such as a cocoon and a low-Lorentz factor jet. We search Fermi data for prompt emission, setting deeper upper limits on the prompt emission than in the original detection paper. Together with KONUS-Wind observations, we show that the gamma-ray efficiency of AT2020blt is 0.3-4.5. We speculate that AT2020blt and AT2021any belong to the low-efficiency tail of long gamma-ray burst distributions that are beginning to be readily observed due to the capabilities of new observatories like the Zwicky Transient Facility.

Original languageEnglish
Pages (from-to)1391-1399
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume512
Issue number1
DOIs
Publication statusPublished - 1 May 2022

Keywords

  • gamma-ray bursts

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  • Extreme astrophysics in the age of gravitational waves

    Lasky, P. (Primary Chief Investigator (PCI))

    Australian Research Council (ARC), Monash University

    30/06/17 → 18/11/21

    Project: Research

  • ARC Centre of Excellence for Gravitational Wave Discovery

    Bailes, M. (Primary Chief Investigator (PCI)), McClelland, D. E. (Chief Investigator (CI)), Levin, Y. (Chief Investigator (CI)), Blair, D. G. (Chief Investigator (CI)), Scott, S. M. (Chief Investigator (CI)), Ottaway, D. J. (Chief Investigator (CI)), Melatos, A. (Chief Investigator (CI)), Veitch, P. J. (Chief Investigator (CI)), Wen, L. (Chief Investigator (CI)), Shaddock, D. A. (Chief Investigator (CI)), Slagmolen, B. J. J. (Chief Investigator (CI)), Zhao, C. (Chief Investigator (CI)), Evans, R. J. (Chief Investigator (CI)), Ju, L. (Chief Investigator (CI)), Galloway, D. (Chief Investigator (CI)), Thrane, E. (Chief Investigator (CI)), Hurley, J. R. (Chief Investigator (CI)), Coward, D. M. (Chief Investigator (CI)), Cooke, J. (Chief Investigator (CI)), Couch, W. (Partner Investigator (PI)), Hobbs, G. B. (Partner Investigator (PI)), Reitze, D. (Partner Investigator (PI)), Rowan, S. (Partner Investigator (PI)), Cai, R. (Partner Investigator (PI)), Adhikari, R. X. (Partner Investigator (PI)), Danzmann, K. (Partner Investigator (PI)), Mavalvala, N. (Partner Investigator (PI)), Kulkarni, S. R. (Partner Investigator (PI)), Kramer, M. (Partner Investigator (PI)), Branchesi, M. (Partner Investigator (PI)), Gehrels, N. (Partner Investigator (PI)), Weinstein, A. J. R. (Partner Investigator (PI)), Steeghs, D. (Partner Investigator (PI)), Bock, D. (Partner Investigator (PI)) & Lasky, P. (Chief Investigator (CI))

    Monash University – Internal University Contribution, Monash University – Internal Department Contribution

    1/01/17 → 31/03/24

    Project: Research

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