jetsimpy: A Highly Efficient Hydrodynamic Code for Gamma-ray Burst Afterglow

Fuente: arXiv
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Auteurs principaux: Wang, Hao, Dastidar, Ranadeep G., Giannios, Dimitrios, Duffell, Paul C.
Format: Preprint
Publié: 2024
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author Wang, Hao
Dastidar, Ranadeep G.
Giannios, Dimitrios
Duffell, Paul C.
author_facet Wang, Hao
Dastidar, Ranadeep G.
Giannios, Dimitrios
Duffell, Paul C.
contents Gamma-ray burst (GRB) afterglows are emissions from ultrarelativistic blast waves produced by a narrow jet interacting with surrounding matter. Since the first multimessenger observation of a neutron star merger, hydrodynamic modeling of GRB afterglows for structured jets with smoothly varying angular energy distributions has gained increased interest. While the evolution of a jet is well described by self-similar solutions in both ultrarelativistic and Newtonian limits, modeling the transitional phase remains challenging. This is due to the nonlinear spreading of a narrow jet to a spherical configuration and the breakdown of self-similar solutions. Analytical models are limited in capturing these nonlinear effects, while relativistic hydrodynamic simulations are computationally expensive, which restricts the exploration of various initial conditions. In this work, we introduce a reduced hydrodynamic model that approximates the blast wave as an infinitely thin two-dimensional surface. Further assuming axial symmetry, this model simplifies the simulation to one dimension and drastically reduces the computational costs. We have compared our modeling to relativistic hydrodynamic simulations and semianalytic methods, and applied it to fit the light curve and flux centroid motion of GRB 170817A. These comparisons demonstrate good agreement and validate our approach. We have developed this method into a numerical tool, \texttt{jetsimpy}, which models the synchrotron GRB afterglow emission from a blast wave with arbitrary angular energy and Lorentz factor distribution. Although the code is built with GRB afterglow in mind, it applies to any relativistic jet. This tool is particularly useful in Markov Chain Monte Carlo studies and is provided to the community.
format Preprint
id arxiv_https___arxiv_org_abs_2402_19359
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle jetsimpy: A Highly Efficient Hydrodynamic Code for Gamma-ray Burst Afterglow
Wang, Hao
Dastidar, Ranadeep G.
Giannios, Dimitrios
Duffell, Paul C.
High Energy Astrophysical Phenomena
Gamma-ray burst (GRB) afterglows are emissions from ultrarelativistic blast waves produced by a narrow jet interacting with surrounding matter. Since the first multimessenger observation of a neutron star merger, hydrodynamic modeling of GRB afterglows for structured jets with smoothly varying angular energy distributions has gained increased interest. While the evolution of a jet is well described by self-similar solutions in both ultrarelativistic and Newtonian limits, modeling the transitional phase remains challenging. This is due to the nonlinear spreading of a narrow jet to a spherical configuration and the breakdown of self-similar solutions. Analytical models are limited in capturing these nonlinear effects, while relativistic hydrodynamic simulations are computationally expensive, which restricts the exploration of various initial conditions. In this work, we introduce a reduced hydrodynamic model that approximates the blast wave as an infinitely thin two-dimensional surface. Further assuming axial symmetry, this model simplifies the simulation to one dimension and drastically reduces the computational costs. We have compared our modeling to relativistic hydrodynamic simulations and semianalytic methods, and applied it to fit the light curve and flux centroid motion of GRB 170817A. These comparisons demonstrate good agreement and validate our approach. We have developed this method into a numerical tool, \texttt{jetsimpy}, which models the synchrotron GRB afterglow emission from a blast wave with arbitrary angular energy and Lorentz factor distribution. Although the code is built with GRB afterglow in mind, it applies to any relativistic jet. This tool is particularly useful in Markov Chain Monte Carlo studies and is provided to the community.
title jetsimpy: A Highly Efficient Hydrodynamic Code for Gamma-ray Burst Afterglow
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2402.19359