# Probing Evolution of Long Gamma-Ray Burst Properties through Their Cosmic Formation History

## TL;DR

This study investigates how the properties and rate density of long gamma-ray bursts evolve over cosmic time, using observational data to compare different evolution models against the star formation rate density.

## Contribution

It demonstrates that simple models like no evolution or single-parameter evolution are insufficient, suggesting multiple evolving properties are needed to explain observations.

## Key findings

- No evolution model can be ruled out.
- Beaming angle or simple power-law evolution alone do not match data.
- Multiple evolving properties are necessary for accurate modeling.

## Abstract

The astrophysics of Long GRB (LGRB) progenitors as well as possible cosmological evolution in their properties still poses many open questions. Previous studies suggest that the LGRB rate density (LGRB-RD) follows the cosmic star formation rate density (SFRD) only at high-z and attribute this to the metallicity evolution of progenitor stars. For low z, opinions differ on whether the uptick in the LGRB RD is due to a distinct class of low-luminosity GRBs or perhaps even a different progenitor subclass. To investigate these questions, we utilize data from the Neil Gehrels Swift Observatory and ground-based observatories (redshift). To test the hypothesis that the observations can be mapped (with/without evolution) to the well-established cosmic SFRD, we consider three cases: no evolution, beaming angle evolution, and a simple power-law evolution. The comparison shows that the 'no evolution' case can be ruled out. Our study highlights that the beaming angle evolution or the simple power law evolution are also not sufficient to obtain a good match between the LGRB-RD and SFRD. Rather, the inclusion of multiple evolving properties of LGRBs in combination appears to be required to match the two rate densities in their entirety.