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Implications of a rapidly varying FRB in a globular cluster of M81

Lu, Wenbin and Beniamini, Paz and Kumar, Pawan (2022) Implications of a rapidly varying FRB in a globular cluster of M81. Monthly Notices of the Royal Astronomical Society, 510 (2). pp. 1867-1879. ISSN 0035-8711. doi:10.1093/mnras/stab3500.

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A repeating source of fast radio bursts (FRBs) is recently discovered from a globular cluster of M81. Association with a globular cluster (or other old stellar systems) suggests that strongly magnetized neutron stars, which are the most likely objects responsible for FRBs, are born not only when young massive stars undergo core-collapse, but also by mergers of old white dwarfs. We find that the fractional contribution to the total FRB rate by old stellar populations is at least a few per cent, and the precise fraction can be constrained by FRB searches in the directions of nearby galaxies, both star-forming and elliptical ones. Using very general arguments, we show that the activity time of the M81-FRB source is between 10⁴ and 10⁶ yr, and more likely of the order of 10⁵ yr. The energetics of radio outbursts put a lower limit on the magnetic field strength of 10¹³ G, and the spin period ≳ 0.2 s, thereby ruling out the source being a milli-second pulsar. The upper limit on the persistent X-ray luminosity (provided by Chandra), together with the high FRB luminosity and frequent repetitions, severely constrains (or rules out) the possibility that the M81-FRB is a scaled-up version of giant pulses from Galactic pulsars. Finally, the 50-ns variability time of the FRB light curve suggests that the emission is produced in a compact region inside the neutron star magnetosphere, as it cannot be accounted for when the emission is at distances ≳ 10¹⁰ cm.

Item Type:Article
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URLURL TypeDescription Paper
Lu, Wenbin0000-0002-1568-7461
Beniamini, Paz0000-0001-7833-1043
Additional Information:© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 November 29. Received 2021 October 26; in original form 2021 July 6. We thank Eliot Quataert for useful discussion on the evolution of double white dwarf merger remnants and Jonathan Katz for insightful comments on an earlier version of thìs paper. We also thank the participants of the FRB2021 conference for their questions/comments while the work was presented. This work has been funded in part by an NSF grant AST-2009619. WL was supported by the David and Ellen Lee Fellowship at Caltech and Lyman Spitzer, Jr. Fellowship at Princeton University. PB was supported by the Gordon and Betty Moore Foundation, Grant GBMF5076. DATA AVAILABILITY. The data underlying this paper will be shared on reasonable request to the corresponding author.
Funding AgencyGrant Number
David and Ellen Lee Postdoctoral ScholarshipUNSPECIFIED
Princeton UniversityUNSPECIFIED
Gordon and Betty Moore FoundationGBMF5076
Subject Keywords:stars: neutron, radio continuum: transients
Issue or Number:2
Record Number:CaltechAUTHORS:20220309-965827000
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Official Citation:Wenbin Lu, Paz Beniamini, Pawan Kumar, Implications of a rapidly varying FRB in a globular cluster of M81, Monthly Notices of the Royal Astronomical Society, Volume 510, Issue 2, February 2022, Pages 1867–1879,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113842
Deposited By: George Porter
Deposited On:11 Mar 2022 17:29
Last Modified:11 Mar 2022 17:29

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