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Title: FLUCTUATION DYNAMO AT FINITE CORRELATION TIMES AND THE KAZANTSEV SPECTRUM

Fluctuation dynamos are generic to astrophysical systems. The only analytical model of the fluctuation dynamo is the Kazantsev model which assumes a velocity field that is delta-correlated in time. We derive a generalized model of fluctuation dynamos with finite correlation time, τ, using renovating flows. For τ → 0, we recover the standard Kazantsev equation for the evolution of longitudinal magnetic correlation, M{sub L} . To the next order in τ, the generalized equation involves third and fourth spatial derivatives of M{sub L} . It can be recast to one with at most second derivatives of M{sub L} using the Landau-Lifschitz approach. Remarkably, we then find that the magnetic power spectrum remains the Kazantsev spectrum of M(k)∝k {sup 3/2}, in the large k limit, independent of τ.
Authors:
;  [1]
  1. IUCAA, Post Bag 4, Ganeshkhind, Pune 411007 (India)
Publication Date:
OSTI Identifier:
22365286
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 791; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; CORRELATIONS; FLUCTUATIONS; GALAXIES; GINZBURG-LANDAU THEORY; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; TURBULENCE; VELOCITY