HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY

Manasvi Lingam; Amitava Bhattacharjee

doi:10.3847/0004-637X/829/1/51

HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY

Manasvi Lingam, Amitava Bhattacharjee

Astrophysical Sciences

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The role of the Hall term on large-scale dynamo action is investigated by means of the first-order smoothing approximation. It is shown that the standard α coefficient is altered, and is zero when a specific double Beltrami state is attained, in contrast to the Alfvénic state for magnetohydrodynamical dynamos. The β coefficient is no longer positive definite, and thereby enables dynamo action even if α-quenching were to operate. The similarities and differences with the (magnetic) shear-current effect are pointed out, and a mechanism that may be potentially responsible for is advanced. The results are compared against previous studies, and their astrophysical relevance is also highlighted.

Original language	English (US)
Article number	51
Journal	Astrophysical Journal
Volume	829
Issue number	1
DOIs	https://doi.org/10.3847/0004-637X/829/1/51
State	Published - Sep 20 2016

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

ISM: magnetic fields
dynamo
galaxies: magnetic fields
magnetohydrodynamics (MHD)
turbulence

Access to Document

10.3847/0004-637X/829/1/51

Cite this

@article{db06c2409d85465bb5d7052df8c8846f,

title = "HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY",

abstract = "The role of the Hall term on large-scale dynamo action is investigated by means of the first-order smoothing approximation. It is shown that the standard α coefficient is altered, and is zero when a specific double Beltrami state is attained, in contrast to the Alfv{\'e}nic state for magnetohydrodynamical dynamos. The β coefficient is no longer positive definite, and thereby enables dynamo action even if α-quenching were to operate. The similarities and differences with the (magnetic) shear-current effect are pointed out, and a mechanism that may be potentially responsible for is advanced. The results are compared against previous studies, and their astrophysical relevance is also highlighted.",

keywords = "ISM: magnetic fields, dynamo, galaxies: magnetic fields, magnetohydrodynamics (MHD), turbulence",

author = "Manasvi Lingam and Amitava Bhattacharjee",

year = "2016",

month = sep,

day = "20",

doi = "10.3847/0004-637X/829/1/51",

language = "English (US)",

volume = "829",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1",

}

TY - JOUR

T1 - HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY

AU - Lingam, Manasvi

AU - Bhattacharjee, Amitava

PY - 2016/9/20

Y1 - 2016/9/20

N2 - The role of the Hall term on large-scale dynamo action is investigated by means of the first-order smoothing approximation. It is shown that the standard α coefficient is altered, and is zero when a specific double Beltrami state is attained, in contrast to the Alfvénic state for magnetohydrodynamical dynamos. The β coefficient is no longer positive definite, and thereby enables dynamo action even if α-quenching were to operate. The similarities and differences with the (magnetic) shear-current effect are pointed out, and a mechanism that may be potentially responsible for is advanced. The results are compared against previous studies, and their astrophysical relevance is also highlighted.

AB - The role of the Hall term on large-scale dynamo action is investigated by means of the first-order smoothing approximation. It is shown that the standard α coefficient is altered, and is zero when a specific double Beltrami state is attained, in contrast to the Alfvénic state for magnetohydrodynamical dynamos. The β coefficient is no longer positive definite, and thereby enables dynamo action even if α-quenching were to operate. The similarities and differences with the (magnetic) shear-current effect are pointed out, and a mechanism that may be potentially responsible for is advanced. The results are compared against previous studies, and their astrophysical relevance is also highlighted.

KW - ISM: magnetic fields

KW - dynamo

KW - galaxies: magnetic fields

KW - magnetohydrodynamics (MHD)

KW - turbulence

UR - http://www.scopus.com/inward/record.url?scp=84991235546&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84991235546&partnerID=8YFLogxK

U2 - 10.3847/0004-637X/829/1/51

DO - 10.3847/0004-637X/829/1/51

M3 - Article

AN - SCOPUS:84991235546

SN - 0004-637X

VL - 829

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 51

ER -

HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY

Abstract

All Science Journal Classification (ASJC) codes

Keywords

Access to Document

Other files and links

Fingerprint

Cite this