Portal de Periódicos da CAPES

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

2015; IOP Publishing; Volume: 815; Issue: 2 Linguagem: Inglês

10.1088/0004-637x/815/2/102

1538-4357

W. Fong, E. Berger, R. Margutti, B. A. Zauderer,

Astrophysical Phenomena and Observations

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 γ-ray and kinetic energies of Eγ,iso ≈ 2 × 1051 erg, and EK,iso ≈ (1–3) × 1051 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 ≈ (3–15) × 10−3 cm−3, and that ≈80%–95% of bursts have densities of n ≲ 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 ≲ 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 θj = 16 ± 10°. We also calculate a median beaming factor of fb ≈ 0.04, leading to a beaming-corrected total energy release of Etrue ≈ 1.6 × 1050 erg. Furthermore, we calculate a beaming-corrected event rate of Gpc−3 yr−1, or yr−1 within a 200 Mpc volume, the Advanced LIGO/Virgo typical detection distance for NS–NS binaries.