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

Wenbin Lu, Paz Beniamini, Pawan Kumar

פרסום מחקרי: פרסום בכתב עתמאמרביקורת עמיתים


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 10$^{13}\,$G, and the spin period $\gtrsim 0.2\,$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 $\gtrsim 10^{10}\rm \, cm$.

שפה מקוריתאנגלית
עמודים (מ-עד)1867-1879
מספר עמודים13
כתב עתMonthly Notices of the Royal Astronomical Society
מספר גיליון2
מזהי עצם דיגיטלי (DOIs)
סטטוס פרסוםפורסם - פבר׳ 2022

הערה ביבליוגרפית

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

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