Synchrotron Intensity and Polarization Gradients: Tools to Obtain the Magnetization Level in a Turbulent Medium

Author(s)

Carmo, Lorena ^{[1, 2]} ; Gonzalez-Casanov, Diego F. ^[2] ; Falceta-Goncalves, Diego ^{[3, 1]} ; Lazarian, Alex ^[2] ; Zhang, Jian-Fu ^{[2, 4]} ; Ferreira, Ivan ^[5] ; Castro, Manuel ^[1] ; Yang, Bo ^[2] ; Jablonski, Francisco ^[1]

Affiliation

^[1] Inst Nacl Pesquisas Espaciais INPE, Div Astrofis, Av Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Wisconsin, Astron Dept, Madison, WI 53711 - USA

^[3] Univ Sao Paulo, Escola Artes Ciencias & Humanidades, Rua Arlindo Bettio 1000, BR-03828000 Sao Paulo, SP - Brazil

^[4] Xiangtan Univ, Dept Phys, Xiangtan 411105, Hunan - Peoples R China

^[5] Univ Brasilia, Inst Fis, BR-70910900 Brasilia, DF - Brazil

• Document type: Journal article
• Source: ASTROPHYSICAL JOURNAL; v. 905, n. 2 DEC 2020.
• Web of Science Citations: 0

Abstract

Synchrotron intensity and polarization gradients (SIG and SPG), proposed by Lazarian et al. and Lazarian \& Yuen, present a new way to recover the mean magnetic field direction in the plane of the sky. To measure the magnetization level, Lazarian et al. suggested that the methods used in the context of the ``Velocity Gradient Technique{''} could also be used on the SIG and SPG contexts. In this work we test the two proposed methods, named ``top-base{''} and the circular standard deviation, ``S,{''} to obtain the level of magnetization from synchrotron emission. In order to test the methods, we generate synthetic observations from magnetohydrodynamic computer simulations, with Alfvenic Mach numbers, M-A {[}0.2,1.7]. Using a Bayesian analysis we find that the circular standard deviations for the SIG and SPG methods are able to recover the magnetization for cases with signal-to-noise ratio greater than or similar to 5. We found that for weak Faraday depolarization and different angles between the magnetic field direction and the line of sight the magnetization level can still be estimated. (AU)

• FAPESP's process: 15/25972-0 - Development and Characterization of the Detector System of the MIRAX Experiment
• Grantee: Manuel Antonio Castro Ávila
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Special Projects