TY - JOUR
T1 - HALL CURRENT EFFECTS in MEAN-FIELD DYNAMO THEORY
AU - Lingam, Manasvi
AU - Bhattacharjee, Amitava
N1 - Funding Information:
M.L. and A.B. were supported by the NSF Grant No. AGS-1338944 and the DOE Grant No. DE-AC02-09CH-11466. M.L. is grateful to Pallavi Bhat, Luca Comisso, Fatima Ebrahimi, and Nishant K. Singh for their insightful comments and discussions.
Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.
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
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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 -