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Title: Faraday dispersion functions of galaxies

The Faraday dispersion function (FDF), which can be derived from an observed polarization spectrum by Faraday rotation measure synthesis, is a profile of polarized emissions as a function of Faraday depth. We study intrinsic FDFs along sight lines through face-on Milky Way like galaxies by means of a sophisticated galactic model incorporating three-dimensional MHD turbulence, and investigate how much information the FDF intrinsically contains. Since the FDF reflects distributions of thermal and cosmic-ray electrons as well as magnetic fields, it has been expected that the FDF could be a new probe to examine internal structures of galaxies. We, however, find that an intrinsic FDF along a sight line through a galaxy is very complicated, depending significantly on actual configurations of turbulence. We perform 800 realizations of turbulence and find no universal shape of the FDF even if we fix the global parameters of the model. We calculate the probability distribution functions of the standard deviation, skewness, and kurtosis of FDFs and compare them for models with different global parameters. Our models predict that the presence of vertical magnetic fields and the large-scale height of cosmic-ray electrons tend to make the standard deviation relatively large. In contrast, the differences in skewnessmore » and kurtosis are relatively less significant.« less
Authors:
; ;  [1] ;  [2] ;  [3]
  1. University of Kumamoto, 2-39-1, Kurokami, Kumamoto 860-8555 (Japan)
  2. Sydney Institute for Astronomy, School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia)
  3. Department of Physics, School of Natural Sciences, Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
Publication Date:
OSTI Identifier:
22365185
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; CONFIGURATION; COSMIC RADIATION; DISPERSIONS; DISTRIBUTION; DISTRIBUTION FUNCTIONS; EMISSION; FARADAY EFFECT; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MILKY WAY; POLARIZATION; PROBABILITY; SCALE HEIGHT; SPECTRA; STATISTICS; SYNTHESIS; THREE-DIMENSIONAL CALCULATIONS; TURBULENCE