A recent change in the optical and gamma ray polarization of the Crab nebula and pulsar
Moran, Paul Kyne, Gillian Redfern, R. M. Shearer, Andrew
Moran, Paul
Kyne, Gillian
Redfern, R. M.
Shearer, Andrew
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Publication Date
2015-12-31
Type
Article
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Moran, P.; Kyne, G.; Gouiffès, C.; Laurent, P.; Hallinan, G.; Redfern, R. M.; Shearer, A. (2016) 'A recent change in the optical and gamma ray polarization of the Crab nebula and pulsar'. Monthly Notices Of The Royal Astronomical Society, 456 :2974-2981.
Abstract
We report on observations of the polarization of optical and γ-ray photons from the Crab nebula and pulsar system using the Galway Astronomical Stokes Polarimeter (GASP), the Hubble Space Telescope, Advanced Camera for Surveys and the International Gamma-Ray Astrophysics Laboratory satellite (INTEGRAL). These, when combined with other optical polarization observations, suggest that the polarized optical emission and γ-ray polarization changes in a similar manner. A change in the optical polarization angle has been observed by this work, from 109.5 ± 0 ∘ . .∘ 7 in 2005 to 85.3 ± 1 ∘ . .∘ 4 in 2012. On the other hand, the γ-ray polarization angle changed from 115 ± 11° in 2003–2007 to 80 ± 12° in 2012–2014. Strong flaring activities have been detected in the Crab nebula over the past few years by the high-energy γ-ray missions Agile and Fermi, and magnetic reconnection processes have been suggested to explain these observations. The change in the polarized optical and γ-ray emission of the Crab nebula/pulsar as observed, for the first time, by GASP and INTEGRAL may indicate that reconnection is possibly at work in the Crab nebula. We also report, for the first time, a non-zero measure of the optical circular polarization from the Crab pulsar+knot system.
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Oxford journals
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Attribution-NonCommercial-NoDerivs 3.0 Ireland