Measurement of Interstellar Magnetization by Synchrotron Polarization Variance
Ning-Ning Guo (Xiangtan Univ.), Jian-Fu Zhang, Hua-Ping Xiao, Jungyeon Cho, Xue-Juan Yang
arXiv:2404.16310v1 Announce Type: new
Abstract: Since synchrotron polarization fluctuations are related to the fundamental properties of the magnetic field, we propose the polarization intensity variance to measure the Galactic interstellar medium (ISM) magnetization. We confirm the method’s applicability by comparing it with the polarization angle dispersion and its reliability by measuring the underlying Alfv’enic Mach number of MHD turbulence. With the finding of the power-law relation of $mathcal{A} propto M_{rm A}^{2}$ between polarization intensity variance $mathcal{A}$ and Alfv’enic Mach number $M_{rm A}$, we apply the new technique to the Canadian Galactic Plane Survey (CGPS) data, achieving Alfv’enic Mach number of the Galactic ISM. Our results show that the low-latitude Galactic ISM is dominated by sub-Alf’enic turbulence, with $M_{rm A}$ approximately between 0.5 and 1.0.arXiv:2404.16310v1 Announce Type: new
Abstract: Since synchrotron polarization fluctuations are related to the fundamental properties of the magnetic field, we propose the polarization intensity variance to measure the Galactic interstellar medium (ISM) magnetization. We confirm the method’s applicability by comparing it with the polarization angle dispersion and its reliability by measuring the underlying Alfv’enic Mach number of MHD turbulence. With the finding of the power-law relation of $mathcal{A} propto M_{rm A}^{2}$ between polarization intensity variance $mathcal{A}$ and Alfv’enic Mach number $M_{rm A}$, we apply the new technique to the Canadian Galactic Plane Survey (CGPS) data, achieving Alfv’enic Mach number of the Galactic ISM. Our results show that the low-latitude Galactic ISM is dominated by sub-Alf’enic turbulence, with $M_{rm A}$ approximately between 0.5 and 1.0.