A decade of short-duration gamma-ray burst broadband afterglows: Energetics, circumburst densities, and jet opening angles
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
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 E{sub γ,iso} ≈ 2 × 10{sup 51} erg, and E{sub K,iso} ≈ (1–3) × 10{sup 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 ≈ (3–15) × 10{sup −3} cm{sup −3}, and that ≈80%–95% of bursts have densities of n ≲ 1 cm{sup −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{sup −4} cm{sup −3}, consistent with an intergalactic medium-like environment. Using late-time afterglow data for 11 events, we find a median jet opening angle of θ{sub j} = 16 ± 10°. We also calculate a median beaming factor of f{sub b} ≈ 0.04, leading to a beaming-corrected total energy release of E{sub true} ≈ 1.6 × 10{sup 50} erg. Furthermore, we calculate a beaming-corrected event rate of R{sub true}=270{sub −180}{sup +1580} Gpc{sup −3} yr{sup −1}, or ≈8{sub −5}{sup +47} yr{sup −1} within a 200 Mpc volume, the Advanced LIGO/Virgo typical detection distance for NS–NS binaries.
- OSTI ID:
- 22882348
- Journal Information:
- Astrophysical Journal, Vol. 815, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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