David Coward, Eric Howell, Tsvi Piran, Giulia Stratta, Marica Branchesi, Omer Bromberg, Bruce Gendre, Ronald Burman, Dafne Guetta
Short gamma-ray bursts (SGRBs) observed by {\it Swift} are potentially
revealing the first insight into cataclysmic compact object mergers. To
ultimately acquire a fundamental understanding of these events requires
pan-spectral observations and knowledge of their spatial distribution to
differentiate between proposed progenitor populations. Presently (late 2011)
there are only some 30% of SGRBs with reasonably firm redshifts, and this
sample is highly biased by the limited sensitivity of {\it Swift} to detect
SGRBs. We account for the dominant biases to calculate a realistic SGRB rate
density out to $z\approx0.5$ using the {\it Swift} sample of peak fluxes,
redshifts, and those SGRBs with a beaming angle constraint from X-ray/optical
observations. We find an SGRB lower rate density of $7.1^{+4.9}_{-3.2} $
$\mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$ (assuming isotropic emission), and a
beaming corrected upper limit of $1200^{+840}_{-550}$
$\mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$. Assuming a significant fraction of binary
neutron star mergers produce SGRBs, we calculate lower and upper detection rate
limits of $(1-200)$ yr$^{-1}$ by an ALIGO and Virgo coincidence search. Our
detection rate is similar to the lower and realistic rates inferred from
extrapolations using Galactic pulsar observations and population synthesis.
View original:
http://arxiv.org/abs/1202.2179
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