A RADIO-SELECTED SAMPLE OF GAMMA-RAY BURST AFTERGLOWS

Abstract

We present a catalog of radio afterglow observations of gamma-ray bursts\n(GRBs) over a 14 year period from 1997 to 2011. Our sample of 304 afterglows\nconsists of 2995 flux density measurements (including upper limits) at\nfrequencies between 0.6 GHz and 660 GHz, with the majority of data taken at 8.5\nGHz frequency band (1539 measurements). We use this dataset to carry out a\nstatistical analysis of the radio-selected sample. The detection rate of radio\nafterglows has stayed unchanged almost at 31% before and after the launch of\nthe {\\em Swift} satellite. The canonical long-duration GRB radio light curve at\n8.5 GHz peaks at 3-6 days in the source rest frame, with a median peak\nluminosity of $10^{31}$ erg s$^{-1}$ Hz$^{-1}$. The peak radio luminosities for\nshort-hard bursts, X-ray flashes and the supernova-GRB classes are an order of\nmagnitude or more fainter than this value. There are clear relationships\nbetween the detectability of a radio afterglow and the fluence or energy of a\nGRB, and the X-ray or optical brightness of the afterglow. However, we find few\nsignificant correlations between these same GRB and afterglow properties and\nthe peak radio flux density. We also produce synthetic light curves at\ncentimeter (cm) and millimeter (mm) bands using a range of blastwave and\nmicrophysics parameters derived from multiwavelength afterglow modeling, and we\nuse them to compare to the radio sample. Finding agreement, we extrapolate this\nbehavior to predict the cm and mm behavior of GRBs observed by the Expanded\nVery Large Array and the Atacama Large Millimeter Array.\n