Magnetic Fields in Elliptical Galaxies: An Observational Probe of the Fluctuation Dynamo Action

Author:

Seta Amit,Rodrigues Luiz Felippe S.ORCID,Federrath ChristophORCID,Hales Christopher A.ORCID

Abstract

Abstract Fluctuation dynamos are thought to play an essential role in the evolution of magnetized galaxies, saturating within ∼0.01 Gyr and thus potentially acting as seeds for large-scale mean-field dynamos. However, unambiguous observational confirmation of the fluctuation dynamo action in a galactic environment is still missing. This is because, in spiral galaxies, it is difficult to differentiate between small-scale magnetic fields generated by a fluctuation dynamo and those due to the tangling of the large-scale field. We propose that observations of magnetic fields in elliptical galaxies would directly probe the fluctuation dynamo action. This is motivated by the fact that in ellipticals, due to their lack of significant rotation, the conventional large-scale dynamo is absent and the fluctuation dynamo is responsible for controlling the strength and structure of the magnetic field. By considering turbulence injected by Type Ia supernova explosions and possible magnetic field amplification by cooling flows, we estimate expected magnetic field strengths of in the centers of quiescent elliptical galaxies. We use a semianalytic model of galaxy formation to estimate the distribution and redshift evolution of field strengths, tentatively finding a decrease in magnetic field strength with decreasing redshift. We analyze a historical sample of radio sources that exhibit the Laing–Garrington effect (radio polarization asymmetry in jets) and infer magnetic field strengths between for a uniform thermal electron density and between for the thermal electron density following the King profile. We examine observational techniques for measuring the magnetic field saturation state in elliptical galaxies, focusing on Faraday rotation measure grids, the Laing–Garrington effect, synchrotron emission, and gravitational lensing, and finding appealing prospects for future empirical analysis.

Funder

Marie Sklodowska Curie

STFC

ARC

Publisher

American Astronomical Society

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 10 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. Structure functions with higher-order stencils as a probe to separate small- and large-scale magnetic fields;Monthly Notices of the Royal Astronomical Society;2024-08-10

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

3. Role of magnetic pressure forces in fluctuation dynamo saturation;Monthly Notices of the Royal Astronomical Society;2023-11-09

4. Deep Synoptic Array Science: Two Fast Radio Burst Sources in Massive Galaxy Clusters;The Astrophysical Journal Letters;2023-05-31

5. Magnetic fields and UHECR propagation;EPJ Web of Conferences;2023

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