Dispersion of Magnetic Fields in Molecular Clouds. III

TL;DR

This paper analyzes magnetic field dispersion in molecular clouds using high-resolution polarization data to characterize turbulence spectra and dissipation scales, revealing different power-law behaviors and cutoff scales in various regions.

Contribution

It introduces a method to analyze high-resolution polarization data for turbulence spectra and dissipation scales in molecular clouds, applied to multiple Orion KL regions.

Findings

Power-law turbulence spectrum in Orion KL with index -2.9

Estimated ambipolar diffusion scale of 9.9 mpc in Orion KL

Different spectral indices and cutoff scales in NGC 1333 IRAS 4A and IRAS 16293

Abstract

We apply our technique on the dispersion of magnetic fields in molecular clouds to high spatial resolution Submillimeter Array polarization data obtained for Orion KL in OMC-1, IRAS 16293, and NGC 1333 IRAS 4A. We show how one can take advantage of such high resolution data to characterize the magnetized turbulence power spectrum in the inertial and dissipation ranges. For Orion KL we determine that in the inertial range the spectrum can be approximately fitted with a power law k^-(2.9\pm0.9) and we report a value of 9.9 mpc for {\lambda}_AD, the high spatial frequency cutoff presumably due to turbulent ambipolar diffusion. For the same parameters we have \sim k^-(1.4\pm0.4) and a tentative value of {\lambda}_AD \simeq 2.2 mpc for NGC 1333 IRAS 4A, and \sim k^-(1.8\pm0.3) with an upper limit of {\lambda}_AD < 1.8 mpc for IRAS 16293. We also discuss the application of the technique to interferometry measurements and the effects of the inherent spatial filtering process on the interpretation of the results.