Where are the prompt emitting regions of long GRBs?

Abstract

We have used a simple method to estimate the prompt emission radii of 27 Swift and 37 pre-Swift long gamma-ray bursts with known redshift and jet break time. The prompt γ -rays are found to emit mainly from a beamed jet with dynamic open angle narrower than its geometric open angle, suggesting an obviously dynamic evolution from prompt to follow-up phases for the jetted outflow. Under condition of the external shock scenario, we confirm that long gamma-ray bursts are produced at a larger radius of ∼10 16 cm, which puts a strict constraint on the currently theoretical models.

Mearsuring the prompt emitting regions of short and low-luminosity GRBs

“…However, the Lorentz factor and the radius of 44 low-luminosity GRBs are found to range from 10 to for low-luminosity GRBs are very consistent with that of general long GRBs[4]. Now, we fit the distribution the prompt emitting radii of short and low--luminosity GRBs.…”

“…However, the external shock, the turbulence [5] and the electromagnetic wind could cause a low-luminosity GRB at a radius of cm 16 10 ≈ , which makes it is very uncertain what is the exact mechanism of the low-luminosity GRBs, as well as the normal long GRBs measured in paper I [4]. ACKNOWLEDGMENT We thank Dr. Nat Butler (http://astro.berkeley.edu/~nat/) and D. Y. Chen for helping gather the data of Swift short and low-luminosity GRBs.…”

Superluminal Motions of AGNs and GRBs at Multiple-Frequencies

“…Based on the consideration, the apparent superluminal motion of GRBs in their prompt phase had been studied. For the sake of comparison, 27 Swift and 37 pre-Swift long GRBs with known redshift, duration time and jet break time are taken from Zhang, Zhao & Zhang (2011). In addition, I pay particular attention to GRB 170817A whose redshift, lorentz factor and viewing angle are estimated as z = 0.0098 (Levan et al 2017)…”