Iterative removal of sources to model the turbulent electromotive force

Author:

Bendre Abhijit B12ORCID,Schober Jennifer1ORCID,Dhang Prasun34ORCID,Subramanian Kandaswamy35ORCID

Affiliation:

1. Institute of Physics, Laboratory of Astrophysics , École Polytechnique Fédérale de Lausanne (EPFL), CH-1290 Sauverny , Switzerland

2. Scuola Normale Superiore di Pisa , Piazz dei Cavalieri 7, 56126 , Italy

3. IUCAA , Post Bag 4, Ganeshkhind, Pune 411007 , India

4. JILA, University of Colorado and National Institute of Standards and Technology , 440 UCB, Boulder, CO 80309-0440 , USA

5. Department of Physics, Ashoka University , Rajiv Gandhi Education City, Rai, Sonipat 131029, Haryana , India

Abstract

ABSTRACT We describe a novel method to compute the components of dynamo tensors from direct magnetohydrodynamic (MHD) simulations. Our method relies upon an extension and generalization of the standard Högbom CLEAN algorithm widely used in radio astronomy to systematically remove the impact of the strongest beams on to the corresponding image. This generalization, called the Iterative Removal of Sources (IROS) method, has been adopted here to model the turbulent electromotive force (EMF) in terms of the mean magnetic fields and currents. Analogous to the CLEAN algorithm, IROS treats the time series of the mean magnetic field and current as beams that convolve with the dynamo coefficients which are treated as (clean) images to produce the EMF time series (the dirty image). We apply this method to MHD simulations of galactic dynamos, to which we have previously employed other methods of computing dynamo coefficients such as the test-field method, the regression method, as well as local and non-local versions of the singular value decomposition (SVD) method. We show that our new method reliably recovers the dynamo coefficients from the MHD simulations. It also allows priors on the dynamo coefficients to be incorporated easily during the inversion, unlike in earlier methods. Moreover, using synthetic data, we demonstrate that it may serve as a viable post-processing tool in determining the dynamo coefficients, even when the power of additive noise to the EMF is twice as much the actual EMF.

Funder

Swiss National Science Foundation

Publisher

Oxford University Press (OUP)

Cited by 1 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Computational approaches to modeling dynamos in galaxies;Living Reviews in Computational Astrophysics;2024-07-02

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