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Growth of Beam–Plasma Instabilities in the Presence of Background Inhomogeneity

Shalaby, Mohamad and Broderick, Avery E. and Chang, Philip and Pfrommer, Christoph and Lamberts, Astrid and Puchwein, Ewald (2018) Growth of Beam–Plasma Instabilities in the Presence of Background Inhomogeneity. Astrophysical Journal, 859 (1). Art. No. 45. ISSN 1538-4357. http://resolver.caltech.edu/CaltechAUTHORS:20180524-133816051

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Abstract

We explore how inhomogeneity in the background plasma number density alters the growth of electrostatic unstable wavemodes of beam–plasma systems. This is particularly interesting for blazar-driven beam–plasma instabilities, which may be suppressed by inhomogeneities in the intergalactic medium (IGM) as was recently claimed in the literature. Using high-resolution particle-in-cell simulations with the SHARP code, we show that the growth of the instability is local, i.e., regions with almost homogeneous background density will support the growth of the Langmuir waves even when they are separated by strongly inhomogeneous regions, resulting in an overall slower growth of the instability. We also show that if the background density is continuously varying, the growth rate of the instability is lower, although in all cases the system remains within the linear regime longer and the instability is not extinguished. In all cases, the beam loses approximately the same fraction of its initial kinetic energy in comparison to the uniform case at nonlinear saturation. Thus, inhomogeneities in the IGM are unlikely to suppress the growth of blazar-driven beam–plasma instabilities.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/aabe92DOIArticle
https://arxiv.org/abs/1804.05071arXivDiscussion Paper
ORCID:
AuthorORCID
Shalaby, Mohamad0000-0001-9625-5929
Broderick, Avery E.0000-0002-3351-760X
Chang, Philip0000-0002-2137-2837
Pfrommer, Christoph0000-0002-7275-3998
Lamberts, Astrid0000-0001-8740-0127
Additional Information:© 2018 The American Astronomical Society. Received 2018 March 8; revised 2018 April 2; accepted 2018 April 12; published 2018 May 23. M.S. and A.E.B. received financial support from the Perimeter Institute for Theoretical Physics and the Natural Sciences and Engineering Research Council of Canada through a Discovery Grant. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research and Innovation. P.C. gratefully acknowledges support from NSF grant AST-1255469. C.P. acknowledges support by the European Research Council under ERC-CoG grant CRAGSMAN-646955. A.L. receives financial support from an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant 411920 and CAREER grant 1455342. E.P. acknowledges support by the Kavli Foundation.
Funders:
Funding AgencyGrant Number
Perimeter Institute for Theoretical PhysicsUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Industry CanadaUNSPECIFIED
Ontario Ministry of Research and InnovationUNSPECIFIED
NSFAST-1255469
European Research Council (ERC)CRAGSMAN-646955
Alfred P. Sloan FoundationUNSPECIFIED
NASANNX14AH35G
NSFAST-411920
NSFAST-1455342
Kavli FoundationUNSPECIFIED
Subject Keywords:instabilities – methods: numerical – plasmas – relativistic processes – waves
Record Number:CaltechAUTHORS:20180524-133816051
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180524-133816051
Official Citation:Mohamad Shalaby et al 2018 ApJ 859 45
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86592
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 May 2018 20:55
Last Modified:24 May 2018 20:55

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