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

Lazarían, A.

doi:10.3847/1538-4357/833/2/131

Cited by 72 publications

(75 citation statements)

References 139 publications

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“…In view of the magnetic field wandering (see LV99), the slow modes initially propagating along magnetic field lines can develop the perpendicular motions and therefore the approximation of q = 0 breaks down. This is similar to the case of Alfvén waves initially propagating along turbulent magnetic field lines (see Lazarian (2016) and references therein). In addition, by comparing the expressions of damping rates in the strong and weak coupling regimes, it is evident that the interactions between ions and neutrals aid the coupling of the two species on large scales, while the damping effect of ion-neutral collisions is manifested after they are essentially decoupled from each other on small scales (see equation (31b)).…”

Section: General Remarkssupporting

confidence: 78%

Magnetohydrodynamic turbulence and turbulent dynamo in partially ionized plasma

Lazarían

2017

New J. Phys.

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Astrophysical fluids are turbulent, magnetized and frequently partially ionized. As an example of astrophysical turbulence, the interstellar turbulence extends over a remarkably large range of spatial scales and participates in key astrophysical processes happening on different ranges of scales. A significant progress has been achieved in the understanding of the magnetohydrodynamic (MHD) turbulence since the turn of the century, and this enables us to better describe turbulence in magnetized and partially ionized plasmas. In fact, the modern revolutionized picture of the MHD turbulence physics facilitates the development of various theoretical domains, including the damping process for dissipating MHD turbulence and the dynamo process for generating MHD turbulence with many important astrophysical implications. In this paper, we review some important findings from our recent theoretical works to demonstrate the interconnection between the properties of MHD turbulence and those of turbulent dynamo in a partially ionized gas. We also briefly exemplify some new tentative studies on how the revised basic processes influence the associated outstanding astrophysical problems in, such as, magnetic reconnection, cosmic ray scattering, magnetic field amplification in both the early and the present-day universe.

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Section: General Remarkssupporting

confidence: 78%

Magnetohydrodynamic turbulence and turbulent dynamo in partially ionized plasma

Lazarían

2017

New J. Phys.

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“…As a result, the wave energy cascades into smaller scales and is ultimately dissipated (Farmer & Goldreich 2004). This damping rate has only been calculated approximately (e.g., see more recent work of Lazarian 2016). Incorporating this effect is fully compatible with our MHD-PIC framework, and can be studied in future multi-dimensional simulations.…”

Section: Towards More Realistic Simulationsmentioning

confidence: 80%

Magnetohydrodynamic Particle-in-cell Simulations of the Cosmic-Ray Streaming Instability: Linear Growth and Quasi-linear Evolution

Bai

Ostriker

Plotnikov

et al. 2019

ApJ

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The gyro-resonant cosmic-ray (CR) streaming instability is believed to play a crucial role in CR transport, leading to growth of Alfvén waves at small scales that scatter CRs, and impacts the interaction of CRs with the ISM on large scales. However, extreme scale separation (λ pc), low cosmic ray number density (n CR /n ISM ∼ 10 −9 ), and weak CR anisotropy (∼ v A /c) pose strong challenges for proper numerical studies of this instability on a microphysical level. Employing the recently developed magnetohydrodynamic-particle-in-cell (MHD-PIC) method, which has unique advantages to alleviate these issues, we conduct one-dimensional simulations that quantitatively demonstrate the growth and saturation of the instability in the parameter regime consistent with realistic CR streaming in the large-scale ISM. Our implementation of the δf method dramatically reduces Poisson noise and enables us to accurately capture wave growth over a broad spectrum, equally shared between left and right handed Alfvén modes. We are also able to accurately follow the quasi-linear diffusion of CRs subsequent to wave growth, which is achieved by employing phase randomization across periodic boundaries. Full isotropization of the CRs in the wave frame requires pitch angles of most CRs to efficiently cross 90 • , and can be captured in simulations with relatively high wave amplitude and/or high spatial resolution. We attribute this crossing to non-linear wave-particle interaction (rather than mirror reflection) by investigating individual CR trajectories. We anticipate our methodology will open up opportunities for future investigations that incorporate additional physics.

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“…Turbulence can also be super-Alfvénic, M A > 1, and either strong or hydro-like, depending on whether r L /L is greater or less than M −3 A respectively. Lazarian (2016) provides a general study of the Alfvén wave damping rates Γ d for each regime of turbulence. The results are summarized in Table 2. Following Wiener et al (2013) and Ruszkowski et al Table 2.…”

Section: Cosmic Ray Streamingmentioning

confidence: 99%

Role of cosmic-ray streaming and turbulent damping in driving galactic winds

Holguin

Ruszkowski

Lazarían

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Large-scale galactic winds driven by stellar feedback are one phenomenon that influences the dynamical and chemical evolution of a galaxy, redistributing material throughout the circumgalatic medium. Non-thermal feedback from galactic cosmic rays (CRs) -high-energy charged particles accelerated in supernovae and young stars -can impact the efficiency of wind driving. The streaming instability limits the speed at which they can escape. However, in the presence of turbulence, the streaming instability is subject to suppression that depends on the magnetization of turbulence given by its Alfvén Mach number. While previous simulations that relied on a simplified model of CR transport have shown that super-Alfvénic streaming of CRs enhances galactic winds, in the present paper we take into account a realistic model of streaming suppression. We perform three-dimensional magnetohydrodynamic simulations of a section of a galactic disk and find that turbulent damping dependent on local magnetization of turbulent interstellar medium (ISM) leads to more spatially extended gas and CR distributions compared to the earlier streaming calculations, and that scaleheights of these distributions increase for stronger turbulence. Our results indicate that the star formation rate increases with the level of turbulence in the ISM. We also find that the instantaneous wind mass loading is sensitive to local streaming physics with the mass loading dropping significantly as the strength of turbulence increases.

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

Cited by 72 publications

References 139 publications

Magnetohydrodynamic turbulence and turbulent dynamo in partially ionized plasma

Magnetohydrodynamic turbulence and turbulent dynamo in partially ionized plasma

Magnetohydrodynamic Particle-in-cell Simulations of the Cosmic-Ray Streaming Instability: Linear Growth and Quasi-linear Evolution

Role of cosmic-ray streaming and turbulent damping in driving galactic winds

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