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Scintillation Can Explain the Spectral Structure of the Bright Radio Burst from SGR 1935+2154

Simard, Dana and Ravi, Vikram (2020) Scintillation Can Explain the Spectral Structure of the Bright Radio Burst from SGR 1935+2154. Astrophysical Journal Letters, 899 (1). Art. No. L21. ISSN 2041-8213. https://resolver.caltech.edu/CaltechAUTHORS:20200813-094025490

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Abstract

The discovery of a fast radio burst (FRB) associated with a magnetar in the Milky Way by the Canadian Hydrogen Intensity Mapping Experiment FRB collaboration (CHIME/FRB) and the Survey for Transient Astronomical Radio Emission 2 has provided an unprecedented opportunity to refine FRB emission models. The burst discovered by CHIME/FRB shows two components with different spectra. We explore interstellar scintillation as the origin for this variation in spectral structure. Modeling a weak scattering screen in the supernova remnant associated with the magnetar, we find that a superluminal apparent transverse velocity of the emission region of >9.5c is needed to explain the spectral variation. Alternatively, the two components could have originated from independent emission regions >8.3 × 10⁴ km apart. These scenarios may arise in "far-away" models where the emission originates from well beyond the magnetosphere of the magnetar (for example, through a synchrotron maser mechanism set up by an ultrarelativistic radiative shock), but not in "close-in" models of emission from within the magnetosphere. If further radio observations of the magnetar confirm scintillation as the source of the observed variation in spectral structure, this scattering model thus constrains the location of the emission region.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/2041-8213/abaa40DOIArticle
https://arxiv.org/abs/2006.13184arXivDiscussion Paper
ORCID:
AuthorORCID
Simard, Dana0000-0002-8873-8784
Ravi, Vikram0000-0002-7252-5485
Additional Information:© 2020. The American Astronomical Society. Received 2020 June 23; revised 2020 July 26; accepted 2020 July 29; published 2020 August 13. We thank Christopher Bochenek, Casey Law, and Wenbin Lu for helpful feedback on early drafts of this work. We thank the anonymous reviewer for helpful feedback that has improved the presentation of this work. This research was supported by the National Science Foundation under grant AST-1836018. Software: astropy (Astropy Collaboration et al. 2013; The Astropy Collaboration et al. 2018), pyne2001 (https://pypi.org/project/pyne2001), NE2001 model (Cordes & Lazio 2002, 2003).
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
NSFAST-1836018
Subject Keywords:Neutron stars ; Magnetars ; Radio bursts ; Interstellar scattering
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Neutron stars (1108); Magnetars (992); Radio bursts (1339); Interstellar scattering (854)
Record Number:CaltechAUTHORS:20200813-094025490
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200813-094025490
Official Citation:Dana Simard and Vikram Ravi 2020 ApJL 899 L21
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104948
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:13 Aug 2020 19:50
Last Modified:13 Aug 2020 19:50

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