Time-integrated Polarizations of the GRB X-Ray Flares

Despite decades of studies, the energy dissipation mechanism of the X-ray flares in the afterglow phase of gamma-ray bursts (GRBs) is still debated. If the jet is dominated by the Poynting flux, there would be a large-scale ordered magnetic field in it, and the X-ray flares might be powered by the m...

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Main Authors: Xing-Yao Wang, Mi-Xiang Lan
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Online Access:https://doi.org/10.3847/1538-4357/adee19
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author Xing-Yao Wang
Mi-Xiang Lan
author_facet Xing-Yao Wang
Mi-Xiang Lan
author_sort Xing-Yao Wang
collection DOAJ
description Despite decades of studies, the energy dissipation mechanism of the X-ray flares in the afterglow phase of gamma-ray bursts (GRBs) is still debated. If the jet is dominated by the Poynting flux, there would be a large-scale ordered magnetic field in it, and the X-ray flares might be powered by the magnetic reconnection process. However, if the jet is dynamical energy dominated and the magnetic field is random, the X-ray flares may be generated by the internal shocks of the cold outflow or by the synchrotron emission escaping from the hot plasma. Polarization is very sensitive to the magnetic field configuration in the radiation region; hence, it can be used as a probe of the magnetic field and the corresponding energy dissipation mechanism in the radiation region. In this paper, the magnetic reconnection model, the internal shock model, and the photosphere model are all described by a simple parametric model to study the time-integrated polarizations of the GRB X-ray flares. We found the time-integrated polarization degree of the GRB X-ray flares would concentrate on high values for the magnetic reconnection process and around zero for the internal shock or the photosphere origin. The influences of the parameters on the time-integrated polarizations are also discussed. Therefore, the statistical properties of the polarizations obtained by the dedicated polarization detector, Low-energy Polarimetry Detector on board POLAR-2, would make a distinction of the energy dissipation processes in the radiation region of the GRB X-ray flares.
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spelling doaj-art-08c85daedd3d4c0398ae7e950044c8442025-08-20T03:36:14ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01989217210.3847/1538-4357/adee19Time-integrated Polarizations of the GRB X-Ray FlaresXing-Yao Wang0Mi-Xiang Lan1https://orcid.org/0000-0001-5641-2598Center for Theoretical Physics and College of Physics, Jilin University , Changchun, 130012, People’s Republic of China ; lanmixiang@jlu.edu.cnCenter for Theoretical Physics and College of Physics, Jilin University , Changchun, 130012, People’s Republic of China ; lanmixiang@jlu.edu.cnDespite decades of studies, the energy dissipation mechanism of the X-ray flares in the afterglow phase of gamma-ray bursts (GRBs) is still debated. If the jet is dominated by the Poynting flux, there would be a large-scale ordered magnetic field in it, and the X-ray flares might be powered by the magnetic reconnection process. However, if the jet is dynamical energy dominated and the magnetic field is random, the X-ray flares may be generated by the internal shocks of the cold outflow or by the synchrotron emission escaping from the hot plasma. Polarization is very sensitive to the magnetic field configuration in the radiation region; hence, it can be used as a probe of the magnetic field and the corresponding energy dissipation mechanism in the radiation region. In this paper, the magnetic reconnection model, the internal shock model, and the photosphere model are all described by a simple parametric model to study the time-integrated polarizations of the GRB X-ray flares. We found the time-integrated polarization degree of the GRB X-ray flares would concentrate on high values for the magnetic reconnection process and around zero for the internal shock or the photosphere origin. The influences of the parameters on the time-integrated polarizations are also discussed. Therefore, the statistical properties of the polarizations obtained by the dedicated polarization detector, Low-energy Polarimetry Detector on board POLAR-2, would make a distinction of the energy dissipation processes in the radiation region of the GRB X-ray flares.https://doi.org/10.3847/1538-4357/adee19Gamma-ray burstsMagnetic fieldsStarlight polarization
spellingShingle Xing-Yao Wang
Mi-Xiang Lan
Time-integrated Polarizations of the GRB X-Ray Flares
The Astrophysical Journal
Gamma-ray bursts
Magnetic fields
Starlight polarization
title Time-integrated Polarizations of the GRB X-Ray Flares
title_full Time-integrated Polarizations of the GRB X-Ray Flares
title_fullStr Time-integrated Polarizations of the GRB X-Ray Flares
title_full_unstemmed Time-integrated Polarizations of the GRB X-Ray Flares
title_short Time-integrated Polarizations of the GRB X-Ray Flares
title_sort time integrated polarizations of the grb x ray flares
topic Gamma-ray bursts
Magnetic fields
Starlight polarization
url https://doi.org/10.3847/1538-4357/adee19
work_keys_str_mv AT xingyaowang timeintegratedpolarizationsofthegrbxrayflares
AT mixianglan timeintegratedpolarizationsofthegrbxrayflares