Obtaining strength of magnetic field from E and B modes of dust polarization
arXiv:2306.11571 · doi:10.3847/1538-4357/ace10a
Abstract
We perform numerical simulations of supersonic magnetohydrodynamic (MHD) turbulence and calculate Fourier power spectra of E and B modes arising from dust polarization. We pay close attention to the ratio of E-mode to B-mode spectra (a.k.a. E/B power asymmetry) on small spatial scales. We find that the ratio depends on the strength of the mean magnetic field: the stronger the mean magnetic field is, the smaller the ratio is. More precisely speaking, the ratio scales with the Alfvén Mach number , the root-mean-square velocity divided by the Alfvén speed of the mean magnetic field, when it lies in the range . This result implies that we can use the E/B power asymmetry to constrain the strength of the mean magnetic field in supersonic and super-Alfvénic MHD turbulence.
10 pages, 7 figures, Submitted to ApJ
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