Time-varying Polarized Gamma-Rays from GRB 160821A: Evidence for Ordered Magnetic Fields

Vidushi Sharma; Shabnam Iyyani; Dipankar Bhattacharya; Tanmoy Chattopadhyay; A. R. Rao; E. Aarthy; Santosh V. Vadawale; N. P.S. Mithun; Varun B. Bhalerao; Felix Ryde; Asaf Pe'Er

doi:10.3847/2041-8213/ab3a48

Time-varying Polarized Gamma-Rays from GRB 160821A: Evidence for Ordered Magnetic Fields

Vidushi Sharma
, Shabnam Iyyani
, Dipankar Bhattacharya
, Tanmoy Chattopadhyay
, A. R. Rao
, E. Aarthy
, Santosh V. Vadawale
, N. P.S. Mithun
, Varun B. Bhalerao
, Felix Ryde
, Asaf Pe'Er

Department of Physics - at Bar-Ilan University

Inter-University Centre for Astronomy and Astrophysics India
Stanford University
Tata Institute of Fundamental Research
Physical Research Laboratory India
Indian Institute of Technology Bombay
KTH Royal Institute of Technology
The Oskar Klein Centre for Cosmoparticle Physics
University College Cork

Research output: Contribution to journal › Article › peer-review

47 Scopus citations

Abstract

GRB 160821A is the third most energetic gamma-ray burst observed by the Fermi gamma-ray space telescope. Based on the observations made by the Cadmium Zinc Telluride Imager on board AstroSat, here we report the most conclusive evidence to date of (i) high linear polarization ( detection), and (ii) variation of polarization angle with time, occurring twice during the rise and decay phase of the burst at 3.5σ and 3.1σ detections, respectively. All confidence levels are reported for two parameters of interest. These observations strongly suggest synchrotron radiation produced in magnetic field lines that are highly ordered on angular scales of 1/Γ, where Γ is the Lorentz factor of the outflow.

Original language	English
Article number	L10
Journal	Astrophysical Journal Letters
Volume	882
Issue number	1
DOIs	https://doi.org/10.3847/2041-8213/ab3a48
State	Published - 1 Sep 2019

Bibliographical note

Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved..

Funding

Funders	Funder number
Horizon 2020 Framework Programme	773062

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10.3847/2041-8213/ab3a48

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abstract = "GRB 160821A is the third most energetic gamma-ray burst observed by the Fermi gamma-ray space telescope. Based on the observations made by the Cadmium Zinc Telluride Imager on board AstroSat, here we report the most conclusive evidence to date of (i) high linear polarization ( detection), and (ii) variation of polarization angle with time, occurring twice during the rise and decay phase of the burst at 3.5σ and 3.1σ detections, respectively. All confidence levels are reported for two parameters of interest. These observations strongly suggest synchrotron radiation produced in magnetic field lines that are highly ordered on angular scales of 1/Γ, where Γ is the Lorentz factor of the outflow.",

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AU - Sharma, Vidushi

AU - Iyyani, Shabnam

AU - Bhattacharya, Dipankar

AU - Chattopadhyay, Tanmoy

AU - Rao, A. R.

AU - Aarthy, E.

AU - Vadawale, Santosh V.

AU - Mithun, N. P.S.

AU - Bhalerao, Varun B.

AU - Ryde, Felix

AU - Pe'Er, Asaf

PY - 2019/9/1

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N2 - GRB 160821A is the third most energetic gamma-ray burst observed by the Fermi gamma-ray space telescope. Based on the observations made by the Cadmium Zinc Telluride Imager on board AstroSat, here we report the most conclusive evidence to date of (i) high linear polarization ( detection), and (ii) variation of polarization angle with time, occurring twice during the rise and decay phase of the burst at 3.5σ and 3.1σ detections, respectively. All confidence levels are reported for two parameters of interest. These observations strongly suggest synchrotron radiation produced in magnetic field lines that are highly ordered on angular scales of 1/Γ, where Γ is the Lorentz factor of the outflow.

AB - GRB 160821A is the third most energetic gamma-ray burst observed by the Fermi gamma-ray space telescope. Based on the observations made by the Cadmium Zinc Telluride Imager on board AstroSat, here we report the most conclusive evidence to date of (i) high linear polarization ( detection), and (ii) variation of polarization angle with time, occurring twice during the rise and decay phase of the burst at 3.5σ and 3.1σ detections, respectively. All confidence levels are reported for two parameters of interest. These observations strongly suggest synchrotron radiation produced in magnetic field lines that are highly ordered on angular scales of 1/Γ, where Γ is the Lorentz factor of the outflow.

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Time-varying Polarized Gamma-Rays from GRB 160821A: Evidence for Ordered Magnetic Fields

Abstract

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