The Turbulence Velocity Power Spectrum of Neutral Hydrogen in the Small Magellanic Cloud

Chepurnov, A. V.; Burkhart, Blakesley; Lazarían, A.; Stanimirović, Snežana

doi:10.1088/0004-637x/810/1/33

Cited by 61 publications

(67 citation statements)

References 49 publications

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“…In external galaxies, the driving scale can be estimated by measuring the ISM velocity power spectrum, for example using HI gas observations (e.g. Chepurnov et al 2015). Martizzi et al (2015) derived a simple estimate of the turbulent velocity dispersion produced by SNe feedback as a function of mean ambient density and volumetric SN rate, and showed that it agreed with simulations of multiple SNe in a periodic box.…”

Section: Results Of the Energetics Analysismentioning

confidence: 99%

Supernova feedback in a local vertically stratified medium: interstellar turbulence and galactic winds

Martizzi

Fielding

Faucher-Giguère

et al. 2016

Mon. Not. R. Astron. Soc.

126

134

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We use local Cartesian simulations with a vertical gravitational potential to study how supernova (SN) feedback in stratified galactic discs drives turbulence and launches galactic winds. Our analysis includes three disc models with gas surface densities ranging from Milky Way-like galaxies to gas-rich ultra-luminous infrared galaxies (ULIRGs), and two different SN driving schemes (random and correlated with local gas density). In order to isolate the physics of SN feedback, we do not include additional feedback processes. We find that, in these local box calculations, SN feedback excites relatively low mass-weighted gas turbulent velocity dispersions ≈ 3 − 7 km s −1 and low wind mass loading factors η 1 in all the cases we study. The low turbulent velocities and wind mass loading factors predicted by our local box calculations are significantly below those suggested by observations of gas-rich and rapidly star-forming galaxies; they are also in tension with global simulations of disc galaxies regulated by stellar feedback. Using a combination of numerical tests and analytic arguments, we argue that local Cartesian boxes cannot predict the properties of galactic winds because they do not capture the correct global geometry and gravitational potential of galaxies. The wind mass loading factors are in fact not well-defined in local simulations because they decline significantly with increasing box height. More physically realistic calculations (e.g., including a global galactic potential and disc rotation) will likely be needed to fully understand disc turbulence and galactic outflows, even for the idealized case of feedback by SNe alone.

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Section: Results Of the Energetics Analysismentioning

confidence: 99%

Supernova feedback in a local vertically stratified medium: interstellar turbulence and galactic winds

Martizzi

Fielding

Faucher-Giguère

et al. 2016

Mon. Not. R. Astron. Soc.

126

134

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“…tral lines (see Chepurnov et al 2010Chepurnov et al , 2015 or synchrotron emission (see Lazarian & Pogosyan 2012, 2016, while the Alfven Mach number M A can be obtained using anisotropy studies with spectral lines (see Esquivel & Lazarian 2005, Burkhart et al 2014, Esquivel, Lazarian & Pogosyan 2015 or synchrotron studies (see Lazarian & Pogosyan 2012, 2016, Herron et al 2016. In particular the variations of L and M A with the distance from the observer can be obtained using multifrequency polarization studies as explained in Lazarian & Pogosyan (2016).…”

Section: Streaming Of Crs In Galaxiesmentioning

confidence: 99%

Damping of Alfvén Waves by Turbulence and Its Consequences: From Cosmic-Ray Streaming to Launching Winds

Lazarían

2016

ApJ

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This paper considers turbulent damping of Alfven waves in magnetized plasmas. We identify two cases of damping, one related to damping of cosmic rays streaming instability, the other related to damping of Alfven waves emitted by a macroscopic wave source, e.g. stellar atmosphere. The physical difference between the two cases is that in the former case the generated waves are emitted in respect to the local direction of magnetic field, in the latter in respect to the mean field. The scaling of damping is different in the two cases. We the regimes of turbulence ranging from subAlfvenic to superAlfvenic we obtain analytical expressions for the damping rates and define the ranges of applicability of these expressions. Describing the damping of the streaming instability, we find that for subAlfvenic turbulence the range of cosmic ray energies influenced by weak turbulence is unproportionally large compared to the range of scales that the weak turbulence is present. On the contrary, the range of cosmic ray energies affected by strong Alfvenic turbulence is rather limited. A number of astrophysical applications of the process ranging from launching of stellar and galactic winds to propagation of cosmic rays in galaxies and clusters of galaxies is considered. In particular, we discuss how to reconcile the process of turbulent damping with the observed isotropy of the Milky Way cosmic rays.

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“…Widely-used evidence of the turbulence in the ISM is seen in the so-called Big Power Law in the Sky (Armstrong et al 1995;Chepurnov & Lazarian 2010) that reflects the Kolmogorov spectrum of electron density fluctuations, in nonthermal Doppler broadening (see Draine 2011), in the power-law scalings of the fluctuations measured in Position-Position Velocity (PPV) space (see Lazarian & Pogosyan 2000;Stanimirović & Lazarian 2001;Chepurnov et al , 2015Padoan et al 2009) (see Lazarian et al 2009, for a review), and in velocity centroids (see Miesch et al 1999;Miville-Deschênes et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Velocity Gradients as a Tracer for Magnetic Fields

González-Casanova

Lazarían

2017

ApJ

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124

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Strong Alfvénic turbulence develops eddy-like motions perpendicular to the local direction of magnetic fields. This local alignment induces velocity gradients perpendicular to the local direction of the magnetic field. We use this fact to propose a new technique of studying the direction of magnetic fields from observations, the Velocity Gradient Technique (VGT). We test our idea by employing the synthetic observations obtained via 3D MHD numerical simulations for different sonic and Alfvén Mach numbers. We calculate the velocity gradient, Ω, using the velocity centroids. We find that Ω traces the projected magnetic field best for the synthetic maps obtained with sub-Alfvénic simulations providing good point-wise correspondence between the magnetic field direction and that of Ω. The reported alignment is much better than the alignment between the density gradients and the magnetic field and we demonstrated that it can be used to find the magnetic field strength using the analog of Chandrasekhar-Fermi method. This new technique does not require dust polarimetry and our study opens a new way of studying magnetic fields using spectroscopic data.

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The Turbulence Velocity Power Spectrum of Neutral Hydrogen in the Small Magellanic Cloud

Cited by 61 publications

References 49 publications

Supernova feedback in a local vertically stratified medium: interstellar turbulence and galactic winds

Supernova feedback in a local vertically stratified medium: interstellar turbulence and galactic winds

Damping of Alfvén Waves by Turbulence and Its Consequences: From Cosmic-Ray Streaming to Launching Winds

Velocity Gradients as a Tracer for Magnetic Fields

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