GRB Polarization: A Unique Probe of GRB Physics

Gill, Ramandeep; Kole, Merlin; Granot, Jonathan

doi:10.48550/arxiv.2109.03286

Cited by 4 publications

(8 citation statements)

References 282 publications

(467 reference statements)

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“…To break this stalemate, measurements of the gamma-ray polarization have been proposed in the last decades. Such measurements are theorized to be able to answer many open questions regarding GRBs [11].…”

Section: Jinst 19 P08002mentioning

confidence: 99%

Response of the first POLAR-2 prototype to polarized beams

Kole,

Angelis,

Bacelj

et al. 2024

J. Inst.

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POLAR-2 is a dedicated gamma-ray polarimeter currently foreseen to be launched towards the China Space Station around 2027. The design of the detector is based on the legacy of its predecessor mission POLAR which was launched in 2016. POLAR-2 aims to measure the polarization of the Gamma-ray Burst prompt emission within the 30–800 keV energy range. Thanks to its high sensitivity to gamma-ray polarization, as well as its large effective area, POLAR-2 will provide the most precise measurements of this type to date. Such measurements are key to improve our understanding of the astrophysical processes responsible for Gamma-Ray Bursts. The detector consists of a segmented array of plastic scintillator bars, each one of which is read out by a Silicon PhotoMultiplier channel. The flight model of POLAR-2 will contain a total of 6400 scintillators. These are divided into 100 groups of 64 bars each, in so-called polarimeter modules. In recent years, the collaboration has designed and produced the first prototypes of these polarimeter modules and subjected these to space qualification tests. In addition, in April 2023, the first of these modules were calibrated using fully polarized gamma-ray beams at the European Synchrotron Radiation Facility (ESRF) in France. In this work, we will present the results of this calibration campaign and compare these to the simulated performance of the POLAR-2 modules. Potential improvements to the design are also discussed. Finally, the measurements are used, in combination with the verified simulation framework, to estimate the scientific performance of the full POLAR-2 detector and compare it to its predecessor.

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Section: Jinst 19 P08002mentioning

confidence: 99%

Response of the first POLAR-2 prototype to polarized beams

Kole,

Angelis,

Bacelj

et al. 2024

J. Inst.

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“…• Gamma Ray Bursts: Measurement of Gamma ray polarization has the potential to test the proposed models for GRB prompt burst emission mechanism (Covino and Gotz, 2016;McConnell, 2016;Toma et al, 2009), e.g., synchrotron emission from relativistic electrons either in a globally ordered magnetic field (Granot and Königl, 2003;Lyutikov et al, 2003;Nakar et al, 2003) or in a random magnetic field generated in the shock plane within the jet (Medvedev and Loeb, 1999) or emission due to Comptonization of soft photons (Shaviv and Dar, 1995) by the relativistic jet. In the past decade, several dedicated X-ray polarimetry experiments and some of the spectroscopic instruments have reported measurements of X-ray/γ-ray polarization for several GRBs (see reviews by Chattopadhyay (2021); Gill et al (2021);McConnell (2016)). Gamma-Ray Burst Polarimeter (GAP) and CZT Imager (CZTI) aboard AstroSat reported high polarization fractions (>50 %) for a few GRBs (Chattopadhyay et al, 2019;Yonetoku et al, 2011Yonetoku et al, , 2012.…”

Section: Science Drivers Of Gamma Ray Polarimetrymentioning

confidence: 99%

Gamma-Ray Polarimetry

Bernard¹,

Chattopadhyay²,

Kislat³

et al. 2022

Preprint

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While the scientific potential of high-energy X-ray and gamma-ray polarimetry has long been recognized, measuring the polarization of high-energy photons is challenging. To date, there has been very few significant detections from an astrophysical source. However, recent technological developments raise the possibility that this may change in the not-too-distant future. Significant progress has been made in the development of Gamma-ray Burst (GRB) polarimeters and polarization sensitive Compton telescopes. A second-generation dedicated GRB polarimeter, POLAR-2, is under development for launch in 2024, and COSI a secondgeneration polarization sensitive Compton Telescope has been selected by NASA for launch in 2025. This chapter reviews basic concepts and experimental approaches of scattering polarimetry of hard X-rays to MeV γ-rays, and pair production polarimetry of higher-energy photons.

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“…11,12 There are competing models regarding the exact energy dissipation process, radiation mechanism, and radiation transfer processes in the prompt emission phase. 13 It is well established that these combined processes produce a non-thermal spectrum, often fitted with various phenomenological models, such as a power law, power law with an exponential cutoff, Band function, etc. 14,15 Most of the spectral analyses show similar fit statistics when fitted with different physical and empirical models; 16,17 however, different physical models predict different degrees of polarization.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, a statistical analysis of polarization properties of the GRB prompt emission phase can be a very useful tool to constrain the models and answer questions regarding the emission mechanism and geometry of GRB jets. 13,[18][19][20][21] High-energy polarization measurement is a very photon-hungry task. Due to the short-lived nature of the prompt emission phase, it has been extremely difficult to measure polarization of GRBs.…”

Section: Introductionmentioning

confidence: 99%

Prospects of measuring gamma-ray burst polarization with the Daksha mission

Bala,

Mate,

Mehla

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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.The proposed Daksha mission comprises of a pair of highly sensitive space telescopes for detecting and characterizing high-energy transients, such as electromagnetic counterparts of gravitational wave events and gamma-ray bursts (GRBs). Along with spectral and timing analysis, Daksha can also undertake polarization studies of these transients, providing data crucial for understanding the source geometry and physical processes governing high-energy emission. Each Daksha satellite will have 340 pixelated cadmium zinc telluride (CZT) detectors arranged in a quasi-hemispherical configuration without any field-of-view collimation (open detectors). These CZT detectors are good polarimeters in the energy range 100 to 400 keV, and their ability to measure polarization has been successfully demonstrated by the cadmium zinc telluride imager onboard AstroSat. Here, we demonstrate the hard x-ray polarization measurement capabilities of Daksha and estimate the polarization measurement sensitivity (in terms of the minimum detectable polarization: MDP) using extensive simulations. We find that Daksha will have MDP of 30% for a fluence threshold of 10 − 4 erg cm − 2 (in 10 to 1000 keV). We estimate that with this sensitivity, if GRBs are highly polarized, Daksha can measure the polarization of about five GRBs per year.

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GRB Polarization: A Unique Probe of GRB Physics

Abstract: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Cited by 4 publications

References 282 publications

Response of the first POLAR-2 prototype to polarized beams

Response of the first POLAR-2 prototype to polarized beams

Gamma-Ray Polarimetry

Prospects of measuring gamma-ray burst polarization with the Daksha mission

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