Characterizing the Uncertainty in Cluster Magnetic Fields Derived from Rotation Measures

Magnetic fields play vital roles in intracluster media (ICMs), but estimating their strengths and distributions from observations is a major challenge. Faraday rotation measures (RMs) are widely applied to this task, so it is critical to understand inherent uncertainties in RM analysis. In this pape...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal Vol. 888; no. 2; pp. 101 - 116
Main Authors: Johnson, A. R., Rudnick, L., Jones, T. W., Mendygral, P. J., Dolag, K.
Format: Journal Article
Language:English
Published: Philadelphia The American Astronomical Society 10.01.2020
IOP Publishing
Subjects:
Astrophysics
Computational fluid dynamics
Computer simulation
Electron density
Extragalactic magnetic fields
Faraday effect
Field strength
Fluid flow
Galactic clusters
Galaxies
Galaxy clusters
Intracluster medium
Magnetic fields
Magnetohydrodynamics
Parameter uncertainty
Physical properties
Polarimetry
Uncertainty analysis
ISSN:0004-637X, 1538-4357
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Magnetic fields play vital roles in intracluster media (ICMs), but estimating their strengths and distributions from observations is a major challenge. Faraday rotation measures (RMs) are widely applied to this task, so it is critical to understand inherent uncertainties in RM analysis. In this paper, we seek to characterize those uncertainties given the types of information available today, independent of the specific technique used. We conduct synthetic RM observations through the ICM of a galaxy cluster drawn from a magnetohydrodynamic cosmological simulation in which the magnetic field is known. We analyze the synthetic RM observations using an analytical formalism based on commonly used model assumptions, allowing us to relate model physical variables to outcome uncertainties. Despite the simplicity of some assumptions, and unknown physical parameters, we are able to extract an approximate magnitude of the central magnetic field within an apparently irreducible uncertain factor of 3. Principal, largely irreducible, uncertainties come from the unknown depth along the line of sight of embedded polarized sources, the lack of robust coherence lengths from area-constrained polarization sampling, and the unknown scaling between ICM electron density and magnetic field strength. The RM-estimated central magnetic field strengths span more than an order of magnitude including the full range of synthetic experiments.
Bibliography:Galaxies and Cosmology
AAS15797
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 14
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab5d30