Faraday depolarization and induced circular polarization by multipath propagation with application to FRBs
- Creators
- Beniamini, Paz
- Kumar, Pawan
- Narayan, Ramesh
Abstract
We describe how the observed polarization properties of an astronomical object are related to its intrinsic polarization properties and the finite temporal and spectral resolutions of the observing device. Moreover, we discuss the effect that a scattering screen, with non-zero magnetic field, between the source and observer has on the observed polarization properties. We show that the polarization properties are determined by the ratio of observing bandwidth and coherence bandwidth of the scattering screen and the ratio of temporal resolution of the instrument and the variability time of screen, as long as the length over which the Faraday rotation induced by the screen changes by ∼π is smaller than the size of the screen visible to the observer. We describe the conditions under which a source that is 100 per cent linearly polarized intrinsically might be observed as partially depolarized, and how the source's temporal variability can be distinguished from the temporal variability induced by the scattering screen. In general, linearly polarized waves passing through a magnetized scattering screen can develop a significant circular polarization. We apply the work to the observed polarization properties of a few fast radio bursts (FRBs), and outline potential applications to pulsars.
Additional Information
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Accepted 2021 December 17. Received 2021 December 7; in original form 2021 September 17. PB was supported by the Gordon and Betty Moore Foundation, Grant GBMF5076. This work has been funded in part by an NSF grant AST-2009619. DATA AVAILABILITY. The data produced in this study will be shared on reasonable request to the authors.Attached Files
Published - stab3730.pdf
Accepted Version - 2110.00028.pdf
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Additional details
- Alternative title
- Faraday depolarization and induced circular polarization by multi-path propagation with application to FRBs
- Eprint ID
- 114326
- Resolver ID
- CaltechAUTHORS:20220414-27799000
- GBMF5076
- Gordon and Betty Moore Foundation
- AST-2009619
- NSF
- Created
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2022-04-15Created from EPrint's datestamp field
- Updated
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2022-04-15Created from EPrint's last_modified field
- Caltech groups
- TAPIR, Walter Burke Institute for Theoretical Physics