Faraday Rotation Measure due to the Intergalactic Magnetic Field

Takuya Akahori; Dongsu Ryu

doi:10.1088/0004-637X/723/1/476

paper

Faraday Rotation Measure due to the Intergalactic Magnetic Field

arXiv:1009.0570 · doi:10.1088/0004-637X/723/1/476

Abstract

Studying the nature and origin of the intergalactic magnetic field (IGMF) is an outstanding problem of cosmology. Measuring Faraday rotation would be a promising method to explore the IGMF in the large-scale structure (LSS) of the universe. We investigated the Faraday rotation measure (RM) due to the IGMF in filaments of galaxies using simulations for cosmological structure formation. We employed a model IGMF based on turbulence dynamo in the LSS of the universe; it has an average strength of $< B >\sim 10$ nG and a coherence length of several $\times 100 h^{- 1}$ kpc in filaments. With the coherence length smaller than path length, the inducement of RM would be a random walk process, and we found that the resultant RM is dominantly contributed by the density peak along line of sight. The rms of RM through filaments at the present universe was predicted to be $\sim 1 rad m^{- 2}$ . In addition, we predicted that the probability distribution function of $∣ RM ∣$ through filaments follows the log-normal distribution, and the power spectrum of RM in the local universe peaks at a scale of $\sim 1 h^{- 1}$ Mpc. Our prediction of RM could be tested with future instruments.

To appear in ApJ. Pdf with full resolution figures can be downloaded from http://canopus.cnu.ac.kr/ryu/ar.pdf

Faraday Rotation Measure due to the Intergalactic Magnetic Field

Abstract

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