A DECADE OF SHORT-DURATION GAMMA-RAY BURST BROADBAND AFTERGLOWS: ENERGETICS, CIRCUMBURST DENSITIES, AND JET OPENING ANGLES

We present a comprehensive catalog and analysis of broadband afterglow observations for 103 short-duration gamma-ray bursts (GRBs), comprised of all short GRBs from 2004 November to 2015 March with prompt follow-up observations in the X-ray, optical, near-infrared (NIR), and/or radio bands. These afterglow observations have uncovered 71 X-ray detections, 30 optical/NIR detections, and 4 radio detections. Employing the standard afterglow synchrotron model, we perform joint probability analyses for a subset of 38 short GRBs with well-sampled light curves to infer the burst isotropic-equivalent energies and circumburst densities. For this subset, we find median isotropic-equivalent 7-ray and kinetic energies of E-gamma,E-iso approximate to 2 x 10(51) erg, and E-K, (iso) approximate to (1-3) x 10(51) erg, respectively, depending on the values of the model input parameters. We further find that short GRBs occur in low-density environments, with a median density of n approximate to (3-15) x 10(-3) cm(-3), and that 80%-95% of bursts have densities of n less than or similar to 1 cm(-3). We investigate trends between the circumburst densities and host galaxy properties, and find that events located at large projected offsets of >10 effective radii from their hosts exhibit particularly low densities of n less than or similar to 10(-4) cm(-3), consistent with an intergalactic medium-like environment. Using late-time afterglow data for 11 events, we find a median jet opening angle of theta(j), = 16 +/- 10 degrees. We also calculate a median beaming factor of f(b) approximate to 0.04, leading to a beaming-corrected total energy release of E-true approximate to 1.6 x 10(50) erg. Furthermore, we calculate a beaming-corrected event rate of (sic)(true) = 270(180)(-)(+1580) Gpc(-3) yr(-1), or approximate to(+47)(-5) within a 200 Mpc volume, the Advanced LIGO/Virgo typical detection distance for NS-NS binaries.