EXTENDING THE BIG POWER LAW IN THE SKY WITH TURBULENCE SPECTRA FROM WISCONSIN Hα MAPPER DATA

Chepurnov, A. V.; Lazarían, A.

doi:10.1088/0004-637x/710/1/853

Cited by 256 publications

(181 citation statements)

References 22 publications

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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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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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“…These scaling relations are extremely important for obtaining an insight into processes on the small scales. In the ISM, the inertial range of fluctuations is very appreciable, i.e., from hundreds of kilometers to dozens of parsecs (see Armstrong et al 1995 for the data at small scale, and Chepurnov & Lazarian 2010 for its extension to pc scales) and therefore the details of the large-scale driving and of the small-scale dissipation become unimportant for the properties of turbulence at the long range of intermediate scales.…”

Section: Magnetohydrodynamic Turbulencementioning

confidence: 99%

“…Whatever its origin, the signatures of plasma turbulence are seen throughout the universe. Turbulent cascade of energy leads to long "inertial ranges" with power-law spectra that are widely observed, e.g., in the solar wind (Leamon et al 1998;Bale et al 2005), in the ISM (Armstrong et al 1995;Chepurnov & Lazarian 2010), and in the ICM (Schuecker et al 2004;Vogt & Enßlin 2005). Often inertial-range spectra cannot be directly observed, but only large-scale turbulent fluctuations, e.g., through their Doppler broadening of line spectra.…”

Section: Introductionmentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

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Magnetic field lines in astrophysical plasmas are expected to be frozen-in at scales larger than the ion gyroradius. The rapid reconnection of magnetic-flux structures with dimensions vastly larger than the gyroradius requires a breakdown in the standard Alfvén flux-freezing law. We attribute this breakdown to ubiquitous MHD plasma turbulence with power-law scaling ranges of velocity and magnetic energy spectra. Lagrangian particle trajectories in such environments become "spontaneously stochastic," so that infinitely many magnetic field lines are advected to each point and must be averaged to obtain the resultant magnetic field. The relative distance between initial magnetic field lines which arrive at the same final point depends upon the properties of two-particle turbulent dispersion. We develop predictions based on the phenomenological Goldreich & Sridhar theory of strong MHD turbulence and on weak MHD turbulence theory. We recover the predictions of the Lazarian & Vishniac theory for the reconnection rate of large-scale magnetic structures. Lazarian & Vishniac also invoked "spontaneous stochasticity," but of the field lines rather than of the Lagrangian trajectories. More recent theories of fast magnetic reconnection appeal to microscopic plasma processes that lead to additional terms in the generalized Ohm's law, such as the collisionless Hall term. We estimate quantitatively the effect of such processes on the inertial-range turbulence dynamics and find them to be negligible in most astrophysical environments. For example, the predictions of the Lazarian & Vishniac theory are unchanged in Hall MHD turbulence with an extended inertial range, whenever the ion skin depth δ i is much smaller than the turbulent integral length or injection-scale L i .

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“…Studies of power spectra resulted in substantial progress of our understanding of interstellar turbulence. For instance, the Big Power Law in the Sky (Armstrong et al 1995;Chepurnov & Lazarian 2010), as well as studies of random densities (see Elmegreen & Scalo 2004, for a review) and velocities (see Lazarian 2009 for a review; Chepurnov et al 2015), provided convincing evidence for the existence and importance of turbulence in the interstellar media.…”

Section: Discussionmentioning

confidence: 99%

The Phase Coherence of Interstellar Density Fluctuations

Burkhart

Lazarían

2016

ApJ

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Studies of MHD turbulence often investigate the Fourier power spectrum to provide information on the nature of the turbulence cascade. However, the Fourier power spectrum only contains the Fourier amplitudes and rejects all information regarding the Fourier phases. Here, we investigate the utility of two statistical diagnostics for recovering information on Fourier phases in ISM column density maps: the averaged amplitudes of the bispectrum and the phase coherence index (PCI), a new phase technique for the ISM. We create three-dimensional density and two-dimensional column density maps using a set of simulations of isothermal ideal MHD turbulence with a wide range of sonic and Alfvénic Mach numbers. We find that the bispectrum averaged along different angles with respect to either the k 1 or k 2 axis is primarily sensitive to the sonic Mach number while averaging the bispectral amplitudes over different annuli is sensitive to both the sonic and Alfvénic Mach numbers. The PCI of density suggests that the most correlated phases occur in supersonic sub-Alfvénic turbulence and near the shock scale. This suggests that nonlinear interactions with correlated phases are strongest in shock-dominated regions, in agreement with findings from the solar wind. Our results suggest that the phase information contained in the bispectrum and PCI can be used to find the turbulence parameters in column density maps.

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EXTENDING THE BIG POWER LAW IN THE SKY WITH TURBULENCE SPECTRA FROM WISCONSIN Hα MAPPER DATA

Cited by 256 publications

References 22 publications

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

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

Fast Magnetic Reconnection and Spontaneous Stochasticity

The Phase Coherence of Interstellar Density Fluctuations

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