Spectral Energy Correlations of Gamma-Ray Bursts from Structured Jets

TL;DR

This study analyzes spectral energy correlations in gamma-ray bursts considering structured jet models, revealing viewing angle dependencies and improved cosmological measurements through in-axis relations.

Contribution

It introduces structured jet corrections to spectral energy relations and demonstrates their impact on viewing angle dependence and cosmological applications.

Findings

Energy relations depend on observer viewing angle within the jet.

In-axis energy relations are steeper and more universal.

In-axis Hubble diagrams serve as better cosmological indicators.

Abstract

Using 148 out-axis gamma-ray bursts, we build their spectrum-energy relations of peak energy versus isotropic energy, peak energy versus peak luminosity and peak energy versus jet-calibrated energy which are corrected for a structured jet model. These relations are found to depend on the observer's viewing angle as long as the observer is within the jet cone. After converting the out-axis energy relations to the in-axis situations, we find that the corresponding in-axis energy relations are universally steeper, of which all of them can be roughly interpreted by the Synchrotron radiation mechanism as shown in Xu et al.. Meanwhile, we notice that the in-axis means of isotropic energies are about one order of magnitude larger than the out-axis means for both short and long bursts except the Supernova-associated gamma-ray bursts. Furthermore, we apply all the newly-found energy relations to construct the Hubble diagrams of out/in-axis bursts. It is found that the in-axis Hubble diagrams are better cosmological indicators.