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The existence of magnetized turbulence in the interstellar HI is well accepted. A number of techniques to obtain turbulence spectrum and magnetic field direction and strength have been developed and successfully applied to HI spectroscopic…

Astrophysics of Galaxies · Physics 2022-02-17 Ka Ho Yuen , Ka Wai Ho , Alex Lazarian

HI data cubes are sources of unique information on interstellar turbulence. Doppler shifts due to supersonic motions contain information on turbulent velocity field which is otherwise difficult to obtain. However, the problem of separation…

Astrophysics · Physics 2007-05-23 A. Lazarian , D. Pogosyan , Alejandro Esquivel

Kalberla et al. used HI4PI data to analyze velocity and density fluctuations in the interstellar medium (ISM). They applied the Yuen et al. (2021) velocity decomposition algorithm (VDA) for separating such fluctuations in the…

Astrophysics of Galaxies · Physics 2022-03-01 P. M. W. Kalberla , J. Kerp , U. Haud

Quantitative description of the statistics of intensity fluctuations within spectral line data cubes introduced in our earlier work is extended to the absorbing media. A possibility of extracting 3D velocity and density statistics from both…

Astrophysics · Physics 2009-11-10 A. Lazarian , D. Pogosyan

We discuss a long-standing problem of how turbulence can be studied using observations of Doppler broadened emission and absorption lines. The focus of the present review is on two new techniques, the Velocity-Channel Analysis (VCA), which…

Astrophysics · Physics 2011-05-10 A. Lazarian

In this paper we test the results of a recent analytical study by Lazarian and Pogosyan, on the statistics of emissivity in velocity channel maps, in the case of realistic density and velocity fields obtained from numerical simulations of…

Astrophysics · Physics 2009-11-06 Alex Lazarian , Dmitri Pogosyan , Enrique Vazquez-Semadeni , Barbara Pichardo

We identify velocity channel map intensities as a new way to trace magnetic fields in turbulent media. This work makes use of both of the modern theory of MHD turbulence predicting that the magnetic eddies are aligned with the local…

Astrophysics of Galaxies · Physics 2018-02-07 A. Lazarian , Ka Ho Yuen

We extend the velocity channel analysis (VCA), introduced by Lazarian & Pogosyan, of the intensity fluctuations in the velocity slices of position-position-velocity (PPV) spectroscopic data from Doppler broadened lines to study statistical…

Astrophysics of Galaxies · Physics 2016-07-12 Dinesh Kandel , Alex Lazarian , Dmitri Pogosyan

In this paper, we develop the method of analyzing the velocity field of cosmic matter with a multiresolution decomposition. This is necessary in calculating the redshift distortion of power spectrum in the discrete wavelet transform (DWT)…

Astrophysics · Physics 2009-11-06 Xiao-Hu Yang , Long-Long Feng , Yao-Quan Chu , Li-Zhi Fang

Turbulence is a key element of the dynamics of astrophysical fluids, including those of interstellar medium, clusters of galaxies and circumstellar regions. Turbulent motions induce Doppler shifts of observable emission and absorption…

Astrophysics · Physics 2010-12-13 A. Lazarian

Emission in spectral lines can provide unique information on interstellar turbulence. Doppler shifts due to supersonic motions contain information on turbulent velocity field which is otherwise difficult to measure. However, the problem of…

Astrophysics · Physics 2016-08-30 A. Lazarian

We study compressible MHD turbulence, which holds key to many astrophysical processes, including star formation and cosmic ray propagation. To account for the variations of the magnetic field in the strongly turbulent fluid we use wavelet…

Astrophysics of Galaxies · Physics 2015-05-18 Grzegorz Kowal , Alex Lazarian

We discuss a new technique for studying astrophysical turbulence that utilizes the statistics of Doppler-broadened spectral lines. The technique relates the power Velocity Coordinate Spectrum (VCS), i.e. the spectrum of fluctuations…

Astrophysics · Physics 2009-11-11 A. Lazarian , D. Pogosyan

Turbulence is a crucial component of dynamics of astrophysical fluids dynamics, including those of ISM, clusters of galaxies and circumstellar regions. Doppler shifted spectral lines provide a unique source of information on turbulent…

Astrophysics · Physics 2016-01-27 A. Lazarian

The distribution of atomic hydrogen in the Galactic plane is usually mapped using the Doppler shift of 21cm emission line. We calculate the emission spectrum in velocity slices of data (channel maps) and derive its dependence on the…

Astrophysics · Physics 2009-10-31 A. Lazarian , D. Pogosyan

We compare velocity structure in the Polaris Flare molecular cloud at scales ranging from 0.015 pc to 20 pc to simulations of supersonic hydrodynamic and MHD turbulence computed with the ZEUS MHD code. We use several different statistical…

Astrophysics · Physics 2007-05-23 Volker Ossenkopf , Mordecai-Mark Mac Low

Turbulence is a crucial component of dynamics of astrophysical fluids dynamics, including those of ISM, clusters of galaxies and circumstellar regions. Doppler shifted spectral lines provide a unique source of information on turbulent…

Astrophysics · Physics 2007-05-23 A. Lazarian

We study the effect of dust absorption on the recovery velocity and density spectra as well as on the anisotropies of magnetohydrodynamic turbulence using the Velocity Channel Analysis (VCA), Velocity Coordinate Spectrum (VCS) and Velocity…

Astrophysics of Galaxies · Physics 2017-08-11 D. Kandel , A. Lazarian , D. Pogosyan

We study possibility of obtaining velocity spectra by studying turbulence in an optically thick medium using velocity centroids (VCs).We find that the regime of universal, i.e. independent of underlying turbulence statistics, fluctuations…

Astrophysics of Galaxies · Physics 2016-10-12 D. Kandel , A. Lazarian , D. Pogosyan

In this work we investigate the Principal Component Analysis (PCA) sensitivity to the velocity power spectrum in high opacity regimes of the interstellar medium (ISM). For our analysis we use synthetic Position-Position-Velocity (PPV) cubes…

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