skip to main content

SciTech ConnectSciTech Connect

Title: TWO POPULATIONS OF GAMMA-RAY BURST RADIO AFTERGLOWS

The detection rate of gamma-ray burst (GRB) afterglows is ∼30% at radio wavelengths, much lower than in the X-ray (∼95%) or optical (∼70%) bands. The cause of this low radio detection rate has previously been attributed to limited observing sensitivity. We use visibility stacking to test this idea, and conclude that the low detection rate is instead due to two intrinsically different populations of GRBs: radio-bright and radio-faint. We calculate that no more than 70% of GRB afterglows are truly radio-bright, leaving a significant population of GRBs that lack a radio afterglow. These radio-bright GRBs have higher gamma-ray fluence, isotropic energies, X-ray fluxes, and optical fluxes than the radio-faint GRBs, thus confirming the existence of two physically distinct populations. We suggest that the gamma-ray efficiency of the prompt emission is responsible for the difference between the two populations. We also discuss the implications for future radio and optical surveys.
Authors:
; ;  [1]
  1. Also at Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), The University of Sydney, Sydney, NSW 2006, Australia. (Australia)
Publication Date:
OSTI Identifier:
22270790
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AFTERGLOW; ASTRONOMY; ASTROPHYSICS; COSMIC GAMMA BURSTS; COSMIC GAMMA SOURCES; COSMIC X-RAY SOURCES; DETECTION; EFFICIENCY; SENSITIVITY; VISIBILITY