Optimum frequency of Faraday tomography to explore the intergalactic magnetic field in filaments of galaxies. (24th November 2018)

• Record Type: Journal Article
• Authors: Akahori, Takuya; Ideguchi, Shinsuke; Aoki, Takahiro; Takefuji, Kazuhiro; Ujihara, Hideki; Takahashi, Keitaro
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 70:Number 6(2018:Dec.)
• Publication Date: 2018-11-24
• Subjects: intergalactic medium -- large-scale structure of universe -- magnetic fields -- polarization; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psy124
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: Faraday tomography is thought to be a powerful tool to explore the cosmic magnetic field. Broadband radio polarimetric data are essential to ensuring the quality of Faraday tomography, but such data are not easy to obtain because of radio frequency interferences. In this paper, we investigate optimum frequency coverage of Faraday tomography so as to explore the Faraday rotation measure (RM) due to the intergalactic magnetic field (IGMF) in filaments of galaxies. We adopt a simple model of the IGMF and estimate confidence intervals of the model parameters using the Fisher information matrix. We find that meaningful constraints on RM due to the IGMF are available with data at multiple narrowbands which are scattered over the ultra-high frequency (UHF, 300–3000 MHz). The optimum frequency depends on the Faraday thickness of the Milky Way foreground. These results are obtained for a wide brightness range of the background source including fast radio bursts. We discuss the relation between the polarized-intensity spectrum and the optimum frequency.