GRB Opening Angle & Space Density Distribution Determined from the GRB Intensity Distribution
Recent research results indicate that long gamma-ray bursts (GRBs) are produced at cosmological distances and the produced radiation may be constrained mostly in narrow beams. In this paper we determine the gamma-ray burst opening angle and space density distribution directly from the observed GRB intensity distribution. The determined GRB opening angle distribution is consistent with an exponential distribution with a mean opening angle of about 0.03 radian. The determined GRB space density follows the star formation rate until z = 1 but continues to increase monotonically up to at least z = 11.7, suggesting that either the actual star formation rate should peak at significantly higher z than believed previously, or GRBs do not follow the star formation rate for z > 1. The existence of the lower-bound z = 0.28 ± 0.04 for GRB production indicates absence or a much lower rate of massive star formation at the present time.
KeywordsGRB opening angle space density of GRBs
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