Faraday dispersion functions of galaxies

Journal Article · Mon Sep 01 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/792/1/51· OSTI ID:22365185

Ideguchi, Shinsuke; Tashiro, Yuichi; Takahashi, Keitaro ^[1]; Akahori, Takuya ^[2]; Ryu, Dongsu ^[3]

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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)

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 skewness and kurtosis are relatively less significant.

• OSTI ID: 22365185
• Journal Information: Astrophysical Journal, Vol. 792, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

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