Modeling the early afterglow in the short and hard GRB 090510

TL;DR

This paper models the early afterglow of GRB 090510 using a leptonic external shock scenario, explaining multiwavelength observations and suggesting magnetic field amplification in neutron star mergers.

Contribution

It presents a novel leptonic external shock model for GRB 090510's early afterglow, incorporating synchrotron and synchrotron self-Compton emissions in a homogeneous medium.

Findings

Long-lasting LAT, X-ray, and optical fluxes explained by synchrotron emission from forward shock.

Bright LAT peak consistent with synchrotron self-Compton from reverse shock.

Evidence supporting magnetic field amplification in neutron star merger environment.

Abstract

The bright, short and hard GRB 090510 was detected by all instruments aboard Fermi and Swift satellites. The multiwavelength observations of this burst presented similar features with the Fermi-LAT-detected gamma-ray bursts. In the framework of the external shock model of early afterglow, a leptonic scenario that evolves in a homogeneous medium is proposed to revisit GRB 090510 and explain the multiwavelength light curve observations presented in this burst. These observations are consistent with the evolution of a jet before and after the jet break. The long-lasting LAT, X-ray and optical fluxes are explained in the synchrotron emission from the adiabatic forward shock. Synchrotron self-Compton emission from the reverse shock is consistent with the bright LAT peak provided that progenitor environment is entrained with strong magnetic fields. It could provide compelling evidence of magnetic field amplification in the neutron star merger.