High energy polarimetry of prompt GRB emission

McConnell, Mark L.

doi:10.1016/j.newar.2016.11.001

Cited by 65 publications

(47 citation statements)

References 78 publications

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“…• The polarization sensitivity of e-ASTROGAM is designed to enable measurements of the gammaray polarization fraction in more than 20 GRBs per year (GRBs being promising candidates for highly gamma-ray polarized sources, see, e.g., [93]). Such measurements will provide important information on the magnetization and content (leptons, hadrons, Poynting flux) of the relativistic outflows, and, in the case of GRBs at cosmological distance, will address fundamental questions of physics related to vacuum birefringence and Lorentz invariance violation (e.g., [69]).…”

Section: Scientific Requirementsmentioning

confidence: 99%

The e-ASTROGAM mission

et al. 2017

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e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV -the lower energy limit can be pushed to energies as low as 150 keV, albeit with rapidly degrading angular resolution, for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and the promise of eLISA.

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Section: Scientific Requirementsmentioning

confidence: 99%

The e-ASTROGAM mission

et al. 2017

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“…Linear polarisation measurement of the prompt emission of GRBs is a powerful tool, in addition to spectral analysis, to strongly constrain the radiation process, geometry of the emitting region and the composition of the GRB outflow (Covino & Gotz 2016). Currently, polarisation measurement of prompt emission has been reported for only a handful of cases (Wigger et al 2004;Willis et al 2005;McGlynn et al 2007;Götz et al 2009;McGlynn et al 2009;Yonetoku et al 2011Yonetoku et al , 2012Götz et al 2013Götz et al , 2014Zhang et al 2019;Burgess et al 2019b;Chand et al 2018Chand et al , 2019Sharma et al 2019;Chattopadhyay et al 2019; for a recent review see McConnell 2017). Linear polarisation has also been measured in early optical afterglows of a few GRBs (Wijers et al 1999;Covino et al 2002;Greiner et al 2003;King et al 2014;Gorbovskoy et al 2016;Troja et al 2017;Laskar et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Spectropolarimetric analysis of prompt emission of GRB 160325A: jet with evolving environment of internal shocks

Sharma

Iyyani

Bhattacharya

et al. 2020

Monthly Notices of the Royal Astronomical Society

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GRB 160325A is the only bright burst detected by AstroSat CZT Imager in its primary field of view to date. In this work, we present the spectral and polarimetric analysis of the prompt emission of the burst using AstroSat, Fermi and Niel Gehrels Swift observations. The prompt emission consists of two distinct emission episodes separated by a few seconds of quiescent/ mild activity period. The first emission episode shows a thermal component as well as a low polarisation fraction of PF < 37 % at 1.5 σ confidence level. On the other hand, the second emission episode shows a non-thermal spectrum and is found to be highly polarised with PF > 43 % at 1.5σ confidence level. We also study the afterglow properties of the jet using Swift/XRT data. The observed jet break suggests that the jet is pointed towards the observer and has an opening angle of 1.2 • for an assumed redshift, z = 2. With composite modelling of polarisation, spectrum of the prompt emission and the afterglow, we infer that the first episode of emission originates from the photosphere with localised dissipation happening below it, and the second from the optically thin region above the photosphere. The photospheric emission is generated mainly by inverse Compton scattering, whereas the emission in the optically thin region is produced by the synchrotron process. The low radiation efficiency of the burst suggests that the outflow remains baryonic dominated throughout the burst duration with only a subdominant Poynting flux component, and the kinetic energy of the jet is likely dissipated via internal shocks which evolves from an optically thick to optically thin environment within the jet.

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“…And perhaps more challenging obstacle is the detailed calibration required to perform polarization measurements. As several past polarization measurements are not trusted by the community due to a lack of calibration, see for example [18], we decided to first carefully check the accuracy of the POLAR calibration for all incoming photon angles.…”

Section: Introductionmentioning

confidence: 99%

Phase-resolved gamma-ray spectroscopy of the Crab pulsar observed by POLAR

Gauvin

et al. 2019

Journal of High Energy Astrophysics

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The POLAR detector is a space based Gamma-Ray Burst (GRB) polarimeter sensitive in the 15-500 keV energy range. Apart from its main scientific goal as a Gamma-Ray Burst polarimeter it is also able to detect photons from pulsars in orbit. By using the six-months in-orbit observation data, significant pulsation from the PSR B0531+21 (Crab pulsar) was obtained. In this work, we present the precise timing analysis of the Crab pulsar, together with a phase-resolved spectroscopic study using a joint-fitting method adapted for wide field of view instruments like POLAR. By using single power law fitting over the pulsed phase, we obtained spectral indices ranging from 1.718 to 2.315, and confirmed the spectral evolution in a reverse S shape which is homogenous with results from other missions over broadband. We will also show, based on the POLAR in-orbit performance and Geant4 Monte-Carlo simulation, the inferred capabilities of POLAR-2, the proposed follow-up mission of POLAR on board the China Space Station (CSS), for pulsars studies.

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High energy polarimetry of prompt GRB emission

Cited by 65 publications

References 78 publications

The e-ASTROGAM mission

The e-ASTROGAM mission

Spectropolarimetric analysis of prompt emission of GRB 160325A: jet with evolving environment of internal shocks

Phase-resolved gamma-ray spectroscopy of the Crab pulsar observed by POLAR

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