# ICRC 2021

Jul 12 – 23, 2021
Online
Europe/Berlin timezone

## A theoretical model of an off-axis GRB jet

Jul 14, 2021, 6:00 PM
1h 30m
04

#### 04

Talk GAD | Gamma Ray Direct

### Speaker

Mr Boris Betancourt Kamenetskaia

### Description

In light of the most recent observations of late afterglows produced by the merger of compact objects or by the core-collapse of massive dying stars, we research the evolution of the afterglow produced by an off-axis top-hat jet and its interaction with a surrounding medium. The medium is parametrized by a power law distribution of the form $n(r)\propto r^{-k}$, where $k$ is the stratification parameter and contains the development when the surrounding density is constant ($k=0$) or wind-like (k=2). We develop an analytical synchrotron forward-shock model when the outflow is viewed off-axis, and it is decelerated by a stratified medium. Using the X-ray data points collected by a large campaign of orbiting satellites and ground telescopes, we have managed to apply our model and fit the X-ray spectrum of the GRB afterglow associated to SN 2020bvc with conventional parameters. Our model predicts that its circumburst medium is parametrized by a power law with stratification parameter $k=1.5$.

### Keywords

mergers; black holes; neutron stars; compact binary stars; radiation mechanism; nonthermal; ISM; GRB

Subcategory Theoretical Methods

### Primary authors

Nissim Fraija (Astronomy Institute) Mr Antonio Gálvan-Gámez (Instituto de Astronomía, Universidad Nacional Autónoma de México) Dr Rodolfo Barniol Duran (Department of Physics and Astronomy, California State University, Sacramento) Simone Dichiara (Universidad Nacional Autónoma de México)