Turbulence Spectra from Doppler-broadened Spectral Lines: Tests of the Velocity Channel Analysis and Velocity Coordinate Spectrum Techniques - AstrophysicsReport as inadecuate




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Abstract: Turbulent motions induce Doppler shifts of observable emission and absorptionlines motivating studies of turbulence using precision spectroscopy. We providethe numerical testing of the two most promising techniques, Velocity ChannelAnalysis VCA and Velocity Coordinate Spectrum VCS. We obtain an expressionfor the shot noise that the discretization of the numerical data entails andsuccessfully test it. We show that the numerical resolution required forrecovering the underlying turbulent spectrum from observations depend on thespectral index of velocity fluctuations, which makes low resolution testingmisleading. We demonstrate numerically that, dealing with absorption lines,sampling of turbulence along just a dozen directions provides a high qualityspectrum with the VCS technique.



Author: A. Chrupnov, A. Lazarian

Source: https://arxiv.org/







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