A Unified Model for GRB Prompt Emission from Optical to $\gamma$-Rays: Exploring GRBs as Standard Candles

TL;DR

This paper presents a multi-component model that explains the broadband prompt emission of GRBs from optical to gamma-ray energies, supporting their potential as standard candles for cosmology.

Contribution

The study introduces a unified multi-component model that fits the entire broadband spectrum of a GRB, linking optical and gamma-ray emissions to a common origin.

Findings

Optical and high-energy gamma-ray emissions originate from the same region.

The model successfully fits GRB 110205A's spectrum from optical to gamma-rays.

Accurate redshift estimation enhances the use of GRBs as standard candles.

Abstract

The origin of prompt emission from gamma ray bursts remains to be an open question. Correlated prompt optical and gamma-ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the broadband GRB spectrum prompted the hypothesis of different emission mechanisms for the low- and high-energy radiations. We demonstrate that our multi-component model for GRB gamma-ray prompt emission provides an excellent fit to GRB 110205A from optical to gamma-ray energies. Our results show that the optical and highest gamma-ray emissions have the same spatial and spectral origin, which is different from the bulk of the X- and softest gamma-ray radiation. Finally, our accurate redshift estimate for GRB 110205A demonstrates promise for using GRBs as cosmological standard candles.