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Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector

Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector
Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector
We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray/gamma-ray sources on the sky, and the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed data analysis of the SGD observation, SGD background estimation, and SGD Monte Carlo simulations, and successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% ± 10.6%), and the polarization angle is 110.7 +13.2/−13.0 in the energy range of 60–160 keV (the errors correspond to the 1 σ deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.0 ± 0.1⁠.
0004-6264
1-19
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9
Gandhi, Poshak
5bc3b5af-42b0-4dd8-8f1f-f74048d4d4a9

Gandhi, Poshak (2018) Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector. Publications of the Astronomical Society of Japan, 70 (6), 1-19, [113]. (doi:10.1093/pasj/psy118).

Record type: Article

Abstract

We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray/gamma-ray sources on the sky, and the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed data analysis of the SGD observation, SGD background estimation, and SGD Monte Carlo simulations, and successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% ± 10.6%), and the polarization angle is 110.7 +13.2/−13.0 in the energy range of 60–160 keV (the errors correspond to the 1 σ deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.0 ± 0.1⁠.

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Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector - Accepted Manuscript
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More information

Accepted/In Press date: 30 September 2018
e-pub ahead of print date: 17 November 2018
Published date: 1 December 2018

Identifiers

Local EPrints ID: 428159
URI: http://eprints.soton.ac.uk/id/eprint/428159
ISSN: 0004-6264
PURE UUID: 88b30eec-3490-478b-810f-7edae4831595
ORCID for Poshak Gandhi: ORCID iD orcid.org/0000-0003-3105-2615

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Date deposited: 13 Feb 2019 17:30
Last modified: 07 Oct 2020 02:06

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Author: Poshak Gandhi ORCID iD

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