The Astrophysical Journal (Jan 2024)

Contemporaneous X-Ray Observations of 30 Bright Radio Bursts from the Prolific Fast Radio Burst Source FRB 20220912A

  • Amanda M. Cook,
  • Paul Scholz,
  • Aaron B. Pearlman,
  • Thomas C. Abbott,
  • Marilyn Cruces,
  • B. M. Gaensler,
  • Fengqiu Adam Dong,
  • Daniele Michilli,
  • Gwendolyn Eadie,
  • Victoria M. Kaspi,
  • Ingrid Stairs,
  • Chia Min Tan,
  • Mohit Bhardwaj,
  • Tomas Cassanelli,
  • Alice P. Curtin,
  • Adaeze L. Ibik,
  • Mattias Lazda,
  • Kiyoshi W. Masui,
  • Ayush Pandhi,
  • Masoud Rafiei-Ravandi,
  • Mawson W. Sammons,
  • Kaitlyn Shin,
  • Kendrick Smith,
  • David C. Stenning

DOI
https://doi.org/10.3847/1538-4357/ad6a13
Journal volume & issue
Vol. 974, no. 2
p. 170

Abstract

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We present an extensive contemporaneous X-ray and radio campaign performed on the repeating fast radio burst (FRB) source FRB 20220912A for 8 weeks immediately following the source’s detection by CHIME/FRB. This includes X-ray data from XMM-Newton, NICER, and Swift, and radio detections of FRB 20220912A from CHIME/Pulsar and Effelsberg. We detect no significant X-ray emission at the time of 30 radio bursts with upper limits on a 0.5–10.0 keV X-ray fluence of (1.5–14.5) × 10 ^−10 erg cm ^−2 (99.7% credible interval, unabsorbed) on a timescale of 100 ms. Translated into a fluence ratio η _x/r = F _X-ray / F _radio , this corresponds to η _x/r < 7 × 10 ^6 . For persistent emission from the location of FRB 20220912A, we derive a 99.7% 0.5–10.0 keV isotropic flux limit of 8.8 × 10 ^−15 erg cm ^−2 s ^−1 (unabsorbed) or an isotropic luminosity limit of 1.4 × 10 ^41 erg s ^−1 at a distance of 362.4 Mpc. We derive a hierarchical extension to the standard Bayesian treatment of low-count and background-contaminated X-ray data, which allows the robust combination of multiple observations. This methodology allows us to place the best (lowest) 99.7% credible interval upper limit on an FRB η _x/r to date, η _x/r < 2 × 10 ^6 , assuming that all 30 detected radio bursts are associated with X-ray bursts with the same fluence ratio. If we instead adopt an X-ray spectrum similar to the X-ray burst observed contemporaneously with FRB-like emission from the Galactic magnetar SGR 1935+2154 detected on 2020 April 28, we derive a 99.7% credible interval upper limit on η _x/r of 8 × 10 ^5 , which is only 3 times the observed value of η _x/r for SGR 1935+2154.

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