Exploring jet structure and dynamics in short gamma-ray bursts: A case study on GRB 090510

¹ Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
² Division of Science, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
³ Department of Astronomical Science, The Graduate University for Advanced Studies, SOKENDAI, Shonankokusaimura, Hayama, Miura District, Kanagawa 240-0115, Japan
⁴ Space Science Institute, 4765 Walnut St Ste B, Boulder, CO 80301, USA
⁵ Nevada Center for Astrophysics, University of Nevada, 4505 Maryland Parkway, Las Vegas, NV 89154, USA

^⋆ Corresponding authors: jsaji@cft.edu.pl; maria.dainotti@nao.ac.jp; agnieszka.janiuk@cft.edu.pl

Received: 15 February 2025
Accepted: 16 July 2025

Abstract

Observations of gamma-ray bursts (GRBs) at high energies enable the emission processes of these still puzzling events to be investigated. In this study, we perform general relativistic magnetohydrodynamic simulations to investigate GRB 090510, a peculiar short GRB detected by Fermi-LAT. Our primary goal is to model the energetics, jet structure, variability, and opening angle of the burst to understand its underlying physical conditions. We tested both 2D and 3D models and estimated the variability timescales. The predicted energetics and the jet opening angle reconcile with the observed ones with 1σ when considering that the jet opening angles also evolve with redshift. Furthermore, we extended our analysis by incorporating dynamical ejecta into selected models to study their impact on jet collimation at smaller distances. In addition, we investigated a suite of models exhibiting a broad range of observable GRB properties, thereby extending our understanding beyond this specific event.