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Main Authors: Zhao, Guoying, Shen, Rong-Feng
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2403.09444
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author Zhao, Guoying
Shen, Rong-Feng
author_facet Zhao, Guoying
Shen, Rong-Feng
contents Expanding X-ray halo or rings appear when short pulses of X-ray radiation from a background source are scattered by clouds of dust in the Milky Way. We study the X-ray rings of the brightest gamma-ray burst (GRB) 221009A, detected by the {\it Swift} X-Ray Telescope. The rings center on the GRB position and their angular radii increase with time. We identify five major expanding rings, and our modeling of their expansion history suggests that they are scattered off, respectively, from five dusty clouds at distances of 0.4-13 kpc from the observer. Given an assumed prompt X-ray fluence of this GRB, the fluxes of those rings suggest that these clouds have dust grain column densities of $10^{7\sim8}~\mathrm{cm^{-2}}$. More interestingly, our time-dependent spectral analysis of these rings show that they all experience spectral softening, i.e., getting softer as they expand, with spectral indices ranging from 2.2 to 5, consistent with what the dust scattering model predicts.
format Preprint
id arxiv_https___arxiv_org_abs_2403_09444
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Expansion and Spectral Softening of the Dust Scattering Rings of GRB 221009A
Zhao, Guoying
Shen, Rong-Feng
High Energy Astrophysical Phenomena
Expanding X-ray halo or rings appear when short pulses of X-ray radiation from a background source are scattered by clouds of dust in the Milky Way. We study the X-ray rings of the brightest gamma-ray burst (GRB) 221009A, detected by the {\it Swift} X-Ray Telescope. The rings center on the GRB position and their angular radii increase with time. We identify five major expanding rings, and our modeling of their expansion history suggests that they are scattered off, respectively, from five dusty clouds at distances of 0.4-13 kpc from the observer. Given an assumed prompt X-ray fluence of this GRB, the fluxes of those rings suggest that these clouds have dust grain column densities of $10^{7\sim8}~\mathrm{cm^{-2}}$. More interestingly, our time-dependent spectral analysis of these rings show that they all experience spectral softening, i.e., getting softer as they expand, with spectral indices ranging from 2.2 to 5, consistent with what the dust scattering model predicts.
title Expansion and Spectral Softening of the Dust Scattering Rings of GRB 221009A
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2403.09444