Electromagnetic Thermal Instability With Momentum and Energy Exchange Between Electrons and Ions in Galaxy Clusters

Nekrasov, A. K.

doi:10.1088/0004-637x/739/2/88

Cited by 7 publications

(17 citation statements)

References 58 publications

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“…In our investigation, we have not included collisions in the momentum equation for the transverse perturbations. It can be shown that in the present case it is possible under condition ω 2 ci ≫ ν ie D 2 ti /ω (e.g., [31,32]) (see also (A15) and (A16)). In the temperature equations, we did not take into account the heating due to viscosity and the Joule heating.…”

Section: Discussionmentioning

confidence: 65%

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Back-reaction instabilities of relativistic cosmic rays

Nekrasov¹

2013

Plasma Phys. Control. Fusion

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We explore streaming instabilities of the electron-ion plasma with relativistic and ultra-relativistic cosmic rays in the background magnetic field in the multi-fluid approach.Cosmic rays can be both electrons and ions. The drift speed of cosmic rays is directed along the magnetic field. In equilibrium, the return current of the background plasma is taken into account. One-dimensional perturbations parallel to the magnetic field are considered.The dispersion relations are derived for transverse and longitudinal perturbations. It is shown that the back-reaction of magnetized cosmic rays generates new instabilities one of which has the growth rate that can approach the growth rate of the Bell instability. These new instabilities can be stronger than the cyclotron resonance instability. For unmagnetized cosmic rays, the growth rate is analogous to the Bell one. We compare two models of the plasma return current in equilibrium with three and four charged components. Some difference between these models is demonstrated. For longitudinal perturbations, an instability is found in the case of ultra-relativistic cosmic rays. The results obtained can be applied to investigation of astrophysical objects such as the shocks by supernova remnants, galaxy clusters, intracluster medium and so on, where interaction of cosmic rays with turbulence of the electron-ion plasma produced by them is of a great importance for the cosmic-ray evolution.

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Section: Discussionmentioning

confidence: 65%

“…T cr0 /m cr c 2 ≫ 1. Then, using equations (A6), (A8), (A10), (A12) and (B13) under conditions defined by equations (32) and (33), we obtain equation (31) in the form…”

Section: Cold Electrons and Ionsmentioning

confidence: 99%

Back-reaction instabilities of relativistic cosmic rays

Nekrasov¹

2013

Plasma Phys. Control. Fusion

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“…For simplicity, we ignore the action of gravity as it has been done by Sharma, Parrish & Quataert (2010). The effects of the gravitational field have been investigated in detail by the multi-fluid approach in papers by Nekrasov & Shadmehri (2010, 2011. Thus, our present study extends previous analytical studies by considering not only the thermal effects but the currents driven by cosmic rays and their back-reaction.…”

Section: Introductionmentioning

confidence: 83%

“…The thermal instability in galaxy clusters in the multi-fluid approach has been considered by Nekrasov (2011Nekrasov ( , 2012. Effects related to cosmic rays were not included in these papers.…”

Section: Introductionmentioning

confidence: 99%

Streaming Cold Cosmic-Ray Back-Reaction and Thermal Instabilities Along the Background Magnetic Field

Nekrasov

Shadmehri

2012

ApJ

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Using the multi-fluid approach, we investigate streaming and thermal instabilities of the electron-ion plasma with homogeneous cold cosmic rays drifting perpendicular to the background magnetic field. Perturbations across the magnetic field are considered. The back-reaction of cosmic rays resulting in the streaming instability is taken into account.The thermal instability is shown not to be subject to the action of cosmic rays in the model under consideration. The dispersion relation for the thermal instability has been derived which includes sound velocities of plasma and cosmic rays, Alfvén and cosmic ray drift velocities. The relation between these parameters determines the kind of thermal instability from Parker's to Field's type instability. The results obtained can be useful for a more detailed the investigation of electron-ion astrophysical objects such as galaxy clusters including the dynamics of streaming cosmic rays.

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“…Subsequent analytic work has focused on extending the theory of TI to account for additional physics including buoyancy effects accompanying gravity in both dynamic flows (Balbus & Soker 1989) and stratified plasmas (e.g., Defouw 1970;Balbus 1986;Malagoli et al 1987;Binney et al 2009); MHD effects in ideal (e.g., Hennebelle & Passot 2006), non-ideal (Heyvaerts 1974;Shadmehri et al 2010) and partially ionized (Stiele et al 2006;Fukue & Kamaya 2007) plasmas; self-gravity (e.g., Gomez-Pelaez & Moreno-Insertis 2002); and variable chemical composition (which leads to the chemothermal instability ;Yoneyama 1972;Sabano & Yoshi 1977). Further extensions to TI are summarized by Nekrasov (2011).…”

Section: Introductionmentioning

confidence: 99%

Non-isobaric Thermal Instability

Waters

Proga

2019

ApJ

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Multiphase media have very complex structure and evolution. Accurate numerical simulations are necessary to make advances in our understanding of this rich physics. Because simulations can capture both the linear and nonlinear evolution of perturbations with a relatively wide range of sizes, it is important to thoroughly understand the stability of condensation and acoustic modes between the two extreme wavelength limits of isobaric and isochoric instability as identified by Field (1965). Partially motivated by a recent suggestion that large non-isobaric clouds can 'shatter' into tiny cloudlets, we revisit the linear theory to survey all possible regimes of thermal instability. We uncover seven regimes in total, one of which allows three unstable condensation modes. Using the code Athena++, we determine the numerical requirements to properly evolve small amplitude perturbations of the entropy mode into the nonlinear regime. Our 1D numerical simulations demonstrate that for a typical AGN cooling function, the nonlinear evolution of a single eigenmode in an isobarically unstable plasma involves increasingly larger amplitude oscillations in cloud size, temperature and density as the wavelength increases. Such oscillations are the hallmark behavior of non-isobaric multiphase gas dynamics and may be observable as correlations between changes in brightness and the associated periodic redshifts and blueshifts in systems that can be spatially resolved. Intriguingly, we discuss regimes and derive characteristic cloud sizes for which the saturation process giving rise to these oscillations can be so energetic that the cloud may indeed break apart. However, we dub this process 'splattering' instead of 'shattering', as it is a different fragmentation mechanism triggered when the cloud suddenly 'lands' on the stable cold branch of the equilibrium curve.

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Electromagnetic Thermal Instability With Momentum and Energy Exchange Between Electrons and Ions in Galaxy Clusters

Cited by 7 publications

References 58 publications

Back-reaction instabilities of relativistic cosmic rays

Back-reaction instabilities of relativistic cosmic rays

Streaming Cold Cosmic-Ray Back-Reaction and Thermal Instabilities Along the Background Magnetic Field

Non-isobaric Thermal Instability

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