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Murchison Widefield Array rapid-response observations of the short GRB 180805A
- Source :
- Publications of the Astronomical Society of Australia, 38:e026. Cambridge University Press
- Publication Year :
- 2021
- Publisher :
- Cambridge University Press, 2021.
-
Abstract
- Here we present stringent low-frequency 185MHz limits on coherent radio emission associated with a short gamma-ray burst (SGRB). Our observations of the short GRB 180805A were taken with the upgraded Murchison Widefield Array (MWA) rapid-response system, which triggered within 20s of receiving the transient alert from Swift, corresponding to 83.7s post-burst. The SGRB was observed for 30m, resulting in a 3sigma persistent flux density upper-limit of 40.2mJy/beam. Transient searches were conducted at the Swift position of this GRB on 0.5s, 5s, 30s, and 2m timescales, resulting in 3sigma limits of 570-1830, 270-630, 200-420, and 100-200mJy/beam, respectively. We also performed a dedispersion search for prompt signals at the position of the SGRB with a temporal and spectral resolution of 0.5s and 1.28MHz, resulting in a 6sigma fluence upper-limit range from 570Jyms at DM=3000pc/cm^3 (z~2.5) to 1750Jyms at DM=200pc/cm^3 (z~0.1). We compare the fluence prompt emission limit and the persistent upper-limit to SGRB coherent emission models assuming the merger resulted in a stable magnetar. Our observations were not sensitive enough to detect prompt emission associated with the alignment of magnetic fields of a binary neutron star just prior to the merger, from the interaction between the relativistic jet and the interstellar medium or persistent pulsar-like emission from the spin-down of the magnetar. However, in the case of a more powerful SGRB (a gamma-ray fluence an order of magnitude higher than GRB 180805A and/or a brighter X-ray counterpart), our MWA observations may be sensitive enough to detect coherent radio emission from the jet-ISM interaction and/or the magnetar remnant. Finally, we demonstrate that of all current low-frequency radio telescopes, only the MWA has the sensitivity and response times capable of probing prompt emission models associated with the initial SGRB merger event.<br />Comment: 20 pages, 11 figures, accepted for publication in PASA
- Subjects :
- High Energy Astrophysical Phenomena (astro-ph.HE)
Physics
010504 meteorology & atmospheric sciences
FOS: Physical sciences
Astronomy and Astrophysics
Murchison Widefield Array
Astrophysics
Astronomy & Astrophysics
Magnetar
01 natural sciences
Redshift
Radio telescope
Interstellar medium
Neutron star
Space and Planetary Science
0103 physical sciences
0201 Astronomical and Space Sciences, 0299 Other Physical Sciences
Spectral resolution
Astrophysics - High Energy Astrophysical Phenomena
Gamma-ray burst
010303 astronomy & astrophysics
0105 earth and related environmental sciences
Subjects
Details
- Language :
- English
- ISSN :
- 14486083 and 13233580
- Volume :
- 38
- Database :
- OpenAIRE
- Journal :
- Publications of the Astronomical Society of Australia
- Accession number :
- edsair.doi.dedup.....a92be706903d1e1423ea2499e37d60a3