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Coherent Nonhelical Shear Dynamos Driven by Magnetic Fluctuations at Low Reynolds Numbers

Squire, J. and Bhattacharjee, A. (2015) Coherent Nonhelical Shear Dynamos Driven by Magnetic Fluctuations at Low Reynolds Numbers. Astrophysical Journal, 813 (1). Art. No. 52. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20151218-110554321

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Abstract

Nonhelical shear dynamos are studied with a particular focus on the possibility of coherent dynamo action. The primary results—serving as a follow up to the results of Squire & Bhattacharjee—pertain to the "magnetic shear-current effect" as a viable mechanism to drive large-scale magnetic field generation. This effect raises the interesting possibility that the saturated state of the small-scale dynamo could drive large-scale dynamo action, and is likely to be important in the unstratified regions of accretion disk turbulence. In this paper, the effect is studied at low Reynolds numbers, removing the complications of small-scale dynamo excitation and aiding analysis by enabling the use of quasi-linear statistical simulation methods. In addition to the magnetically driven dynamo, new results on the kinematic nonhelical shear dynamo are presented. These illustrate the relationship between coherent and incoherent driving in such dynamos, demonstrating the importance of rotation in determining the relative dominance of each mechanism.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/813/1/52DOIArticle
http://iopscience.iop.org/article/10.1088/0004-637X/813/1/52/metaPublisherArticle
Additional Information:© 2015. The American Astronomical Society. Received 2015 July 11; accepted 2015 September 24; published 2015 October 28. This work was supported by a Procter Fellowship at Princeton University, and the US Department of Energy Grant DE-AC02-09-CH11466. We would like to thank A. Schekochihin, J. Krommes, I. Rogachevskii, and G. Lesur for enlightening discussion and useful suggestions.
Group:TAPIR
Funders:
Funding AgencyGrant Number
Princeton University Charlotte Elizabeth Procter FellowshipUNSPECIFIED
Department of Energy (DOE)DE-AC02-09-CH11466
Subject Keywords:accretion, accretion disks – dynamo – magnetic fields – magnetohydrodynamics (MHD) – turbulence
Record Number:CaltechAUTHORS:20151218-110554321
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151218-110554321
Official Citation:J. Squire and A. Bhattacharjee 2015 ApJ 813 52
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63069
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:18 Dec 2015 23:38
Last Modified:18 Dec 2015 23:38

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