Phase-resolved X-ray polarimetry of the Crab pulsar with the AstroSat CZT Imager

Vadawale, S.; Chattopadhyay, Tanmoy; Mithun, N. P. S.; Rao, A. R.; Bhattacharya, Dipankar; Vibhute, A.; Bhalerao, V.; Dewangan, G. C.; Misra, Ranjeev; Paul, Biswajit; Basu, Avishek; Joshi, B. C.; Sreekumar, S.; Samuel, Essy; Priya, P. Aruna; Vinod, P.; Seetha, S.

doi:10.1038/s41550-017-0293-z

Cited by 76 publications

(50 citation statements)

References 31 publications

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“…Moreover, it has been shown that these values do not vary with energy, from 130 to 436 keV. Also, they are in good agreement with those obtained with the 2003 observations by Chauvin et al (2013), INTEGRAL IBIS (Forot et al 2008), PoGOLite+ (Chauvin et al 2017), CZTI instrument on AstroSat (Vadawale et al 2018) and SGD on Hitomi (Hitomi collaboration 2019), when they consider (as done here) the total (Pulsar + nebula) Crab emission. Lastly, our value is comparable to those reported in optical by S lowikowska et al (2009).…”

Section: Discussionsupporting

confidence: 88%

2003–2018 Monitoring of the Crab Nebula Polarization in Hard X-Rays with INTEGRAL SPI

Jourdain

Roques

2019

ApJ

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We have analyzed 16 years of observations dedicated to the Crab(pulsar + nebula) with the INTEGRAL SPI instrument to investigate its polarization properties. We find that the source presents a substantially polarized emission (PF = 24%) in the hard X-ray domain, with the electric vector aligned with the pulsar spin axis, in agreement with other results at various wavelengths. The stability of the polarization characteristics with energy and over the 16 years covered by the data is remarkable, completing the standard candle status of the source in the spectral domain. The polarization measurements imply that the synchrotron emission is the dominant mechanism of photon production from radio to hard X-rays. The high level of polarized emission points out the steadiness of the source, in particular of the magnetic field configuration and geometry.

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Section: Discussionsupporting

confidence: 88%

2003–2018 Monitoring of the Crab Nebula Polarization in Hard X-Rays with INTEGRAL SPI

Jourdain

Roques

2019

ApJ

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“…The upgraded PoGO+ instrument later provided an independent study in the range 19-160 keV, confirming the findings from PoGOLite, significantly improving the statistical precision and producing a result for the off-pulse (nebula-dominated) and second pulse ("P2", off-pulse-subtracted) phase regions, respectively [14]. Since the PoGO+ results were published, results from the AstroSat mission have also been reported [15], in an energy range complementary to that of PoGO+, 100-380 keV. Results from these high-energy studies were collected and are shown in Figure 5, where low-energy optical values from the NOT [16] are also included.…”

Section: Scientific Results From Pogosupporting

confidence: 53%

The PoGO+ Balloon-Borne Hard X-ray Polarimetry Mission

et al. 2018

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Abstract:The PoGO mission, including the PoGOLite Pathfinder and PoGO+, aims to provide polarimetric measurements of the Crab system and Cygnus X-1 in the hard X-ray band. Measurements are conducted from a stabilized balloon-borne platform, launched on a 1 million cubic meter balloon from the Esrange Space Center in Sweden to an altitude of approximately 40 km. Several flights have been conducted, resulting in two independent measurements of the Crab polarization and one of Cygnus X-1. Here, a review of the PoGO mission is presented, including a description of the payload and the flight campaigns, and a discussion of some of the scientific results obtained to date.

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“…Linear polarisation signature in the GRB is estimated through the non-uniform azimuthal distribution of the Compton-scattered photons. First, onboard verification of CZTI X-ray polarimetry measurement capability was done by the measurement of the polarisation of Crab nebula and pulsar in 100-380 keV energy range (Vadawale et al 2018). GRB 160325A has been found to be polarised at > 2σ confidence level with a high polarisation fraction of 59 ± 28 % for the whole burst .…”

Section: Polarisation Measurementsmentioning

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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Phase-resolved X-ray polarimetry of the Crab pulsar with the AstroSat CZT Imager

Cited by 76 publications

References 31 publications

2003–2018 Monitoring of the Crab Nebula Polarization in Hard X-Rays with INTEGRAL SPI

2003–2018 Monitoring of the Crab Nebula Polarization in Hard X-Rays with INTEGRAL SPI

The PoGO+ Balloon-Borne Hard X-ray Polarimetry Mission

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

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