Suppression of Electron Thermal Conduction in the High Β Intracluster Medium of Galaxy Clusters

Roberg-Clark, Gareth; Drake, J. F.; Reynolds, C. S.; Swisdak, M.

doi:10.3847/2041-8205/830/1/l9

Cited by 77 publications

(83 citation statements)

References 23 publications

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“…The recent 1D PIC simulations by Roberg-Clark et al (2016) have also demonstrated that strictly parallel whistler waves are incapable of regulating the electron heat flux in a collisionless plasma. However, the initial electron VDF set by Roberg-Clark et al (2016) is an asymptotic solution of the collisional Fokker-Plank equation (e.g., Pistinner & Eichler 1998), that is very different from electron VDFs typical for the solar wind Maksimovic et al 1997;Tong et al 2019b). In contrast to Roberg-Clark et al (2016), we have presented 1D PIC simulations of the classical WHFI with initial electron VDFs more relevant for the solar wind, so that the results of the simulations can be compared to in-situ measurements.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear Evolution of the Whistler Heat Flux Instability

Kuzichev

Vasko

Soto-chavez

et al. 2019

ApJ

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We use the one-dimensional TRISTAN-MP particle-in-cell code to model the nonlinear evolution of the whistler heat flux instability that was proposed by Gary et al. (1999) and Gary & Li (2000) to regulate the electron heat flux in the solar wind and astrophysical plasmas. The simulations are initialized with electron velocity distribution functions typical for the solar wind. We perform a set of simulations at various initial values of the electron heat flux and β e . The simulations show that parallel whistler waves produced by the whistler heat flux instability saturate at amplitudes consistent with the spacecraft measurements. The simulations also reproduce the correlations of the saturated whistler wave amplitude with the electron heat flux and β e revealed in the spacecraft measurements. The major result is that parallel whistler waves produced by the whistler heat flux instability do not significantly suppress the electron heat flux. The presented simulations indicate that coherent parallel whistler waves observed in the solar wind are unlikely to regulate the heat flux of solar wind electrons.

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Section: Discussionmentioning

confidence: 99%

Nonlinear Evolution of the Whistler Heat Flux Instability

Kuzichev

Vasko

Soto-chavez

et al. 2019

ApJ

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“…Once thermal conduction takes place, the sharp temperature gradient will quickly smooth out and the rate will drop roughly as t 1/2 . (b) Heat flux might be significantly suppressed by magnetic field geometry and microscopic plasma instabilities in the cluster gas (Roberg-Clark et al 2016, 2018b. Although we include magnetic fields in the injection of the jets, the ICM is not magnetized in our simulations.…”

Section: The Conduction Rate and Energy Budgetmentioning

confidence: 99%

Jets, bubbles, and heat pumps in galaxy clusters

Chen

Heinz

Enßlin

2019

Monthly Notices of the Royal Astronomical Society

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Feedback from AGN jets has been proposed to counteract the catastrophic cooling in many galaxy clusters. However, it is still unclear which physical processes are acting to couple the energy from the bi-directional jets to the ICM. We study the long-term evolution of rising bubbles that were inflated by AGN jets using MHD simulations. In the wake of the rising bubbles, a significant amount of low-entropy gas is brought into contact with the hot cluster gas. We assess the energy budget of the uplifted gas and find it comparable to the total energy injected by the jets. Although our simulation does not include explicit thermal conduction, we find that, for reasonable assumptions about the conduction coefficient, the rate is fast enough that much of the uplifted gas may be thermalized before it sinks back to the core. Thus, we propose that the AGN can act like a geothermal heat pump to move low-entropy gas from the cluster core to the heat reservoir and will be able to heat the inner cluster more efficiently than would be possible by direct energy transfer from jets alone. We show that the maximum efficiency of this mechanism, i.e. the ratio between the conductive thermal energy and the work needed to lift the gas, ξ max can exceed 100 per cent. While ξ < ξ max in realistic scenarios, AGN-induced thermal conduction has the potential to significantly increase the efficiency with which AGN can heat cool-core clusters and transform the bursty AGN activities into a smoother and enduring heating process.

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“…The observed radial evolution of the angular width of suprathermal field-aligned electron population (strahl electrons) in the solar wind (e.g., Hammond et al 1996;Graham et al 2017) requires pitch-angle scattering that can be potentially provided by whistler waves (Vocks et al 2005;Shevchenko & Galinsky 2010;Vocks 2012;Kajdič et al 2016;Vasko et al 2019). Whistler waves may also suppress the electron heat flux in collisionless or weakly-collisional astrophysical plasma (Pistinner & Eichler 1998;Gary & Li 2000;Roberg-Clark et al 2016;Roberg-Clark et al 2018;Komarov et al 2018). The necessity of a heat flux suppression mechanism is suggested by observations of the temperature profile of hot gases in galaxy clusters (e.g., Cowie & McKee 1977;Bertschinger & Meiksin 1986;Zakamska & Narayan 2003;Wagh et al 2014;Fang et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Statistical Study of Whistler Waves in the Solar Wind at 1 au

Tong

Vasko

Artemyev

et al. 2019

ApJ

107

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Whistler waves are intermittently present in the solar wind, while their origin and effects are not entirely understood. We present a statistical analysis of magnetic field fluctuations in the whistler frequency range (above 16 Hz) based on about 801,500 magnetic field spectra measured over three years aboard ARTEMIS spacecraft in the pristine solar wind. About 13,700 spectra (30 hours in total) with intense magnetic field fluctuations satisfy the interpretation in terms of quasi-parallel whistler waves. We provide estimates of the whistler wave occurrence probability, amplitudes, frequencies and bandwidths. The occurrence probability of whistler waves is shown to strongly depend on the electron temperature anisotropy. The whistler waves amplitudes are in the range from about 0.01 to 0.1 nT and typically below 0.02 of the background magnetic field. The frequencies of the whistler waves are shown to be below an upper bound that is dependent on β e . The correlations established between the whistler wave properties and local macroscopic plasma parameters suggest that the observed whistler waves can be generated in local plasmas by the whistler heat flux instability. The whistler wave amplitudes are typically small, which questions the hypothesis that quasi-parallel whistler waves are capable to regulate the electron heat flux in the solar wind. We show that the observed whistler waves have sufficiently wide bandwidths and small amplitudes, so that effects of the whistler waves on electrons can be addressed in the frame of the quasi-linear theory.

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Suppression of Electron Thermal Conduction in the High Β Intracluster Medium of Galaxy Clusters

Cited by 77 publications

References 23 publications

Nonlinear Evolution of the Whistler Heat Flux Instability

Nonlinear Evolution of the Whistler Heat Flux Instability

Jets, bubbles, and heat pumps in galaxy clusters

Statistical Study of Whistler Waves in the Solar Wind at 1 au

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