scholarly journals Propagation of weak shocks in cool-core galaxy clusters in two-temperature magnetohydrodynamics with anisotropic thermal conduction

2020 ◽  
Vol 497 (2) ◽  
pp. 1434-1442
Author(s):  
S Komarov ◽  
C Reynolds ◽  
E Churazov
Keyword(s):  
Electron Temperature ◽  
Thermal Conduction ◽  
Galaxy Cluster ◽  
Weak Shock ◽  
Heat Fluxes ◽  
Equilibration Time ◽  
Characteristic Spatial Scale ◽  
Magnetohydrodynamic Models ◽  
Weak Shocks ◽  
Perseus Cluster

ABSTRACT We investigate how different magnetohydrodynamic models of propagation of a weak (Mach number ∼1.2) shock in the core of a galaxy cluster affect its observational appearance, using the Perseus cluster as our fiducial model. In particular, we study how thermal conduction, both isotropic and anisotropic, and ion–electron temperature equilibration modify a weak shock. Strong thermal conduction is expected to produce an electron temperature precursor. Less prominent pressure and density precursors are formed as well. A longer equilibration time largely reduces the density precursor but does not change the electron temperature precursor much. When thermal conduction becomes anisotropic, the intracluster magnetic field imprints its characteristic spatial scale on the distortions of the shock induced by heat fluxes.

scholarly journals High-resolution VLA low radio frequency observations of the Perseus cluster: radio lobes, mini-halo, and bent-jet radio galaxies

2020 ◽  
Vol 499 (4) ◽  
pp. 5791-5805
Author(s):  
M Gendron-Marsolais ◽  
J Hlavacek-Larrondo ◽  
R J van Weeren ◽  
L Rudnick ◽  
T E Clarke ◽  
...  
Keyword(s):  
High Resolution ◽  
Dynamic Range ◽  
Galaxy Cluster ◽  
High Dynamic Range ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Nearby Galaxy ◽  
Cluster Galaxy ◽  
Ngc 1275 ◽  
Perseus Cluster

ABSTRACT We present the first high-resolution 230–470 MHz map of the Perseus cluster obtained with the Karl G. Jansky Very Large Array. The high dynamic range and resolution achieved have allowed the identification of previously unknown structures in this nearby galaxy cluster. New hints of sub-structures appear in the inner radio lobes of the brightest cluster galaxy NGC 1275. The spurs of radio emission extending into the outer X-ray cavities, inflated by past nuclear outbursts, are seen for the first time at these frequencies, consistent with spectral aging. Beyond NGC 1275, we also analyse complex radio sources harboured in the cluster. Two new distinct, narrowly collimated jets are visible in IC 310, consistent with a highly projected narrow-angle tail radio galaxy infalling into the cluster. We show how this is in agreement with its blazar-like behaviour, implying that blazars and bent-jet radio galaxies are not mutually exclusive. We report the presence of filamentary structures across the entire tail of NGC 1265, including two new pairs of long filaments in the faintest bent extension of the tail. Such filaments have been seen in other cluster radio sources such as relics and radio lobes, indicating that there may be a fundamental connection between all these radio structures. We resolve the very narrow and straight tail of CR 15 without indication of double jets, so that the interpretation of such head–tail sources is yet unclear. Finally, we note that only the brightest western parts of the mini-halo remain, near NGC 1272 and its bent double jets.

Interaction between parallel Gaussian electromagnetic beams in ionic collision dominated plasmas with thermal conduction

2008 ◽  
Vol 74 (1) ◽  
pp. 65-77 ◽  
Author(s):  
MAHENDRA SINGH SODHA ◽  
SUJEET KUMAR AGARWAL ◽  
ASHUTOSH SHARMA
Keyword(s):  
Wave Equation ◽  
Energy Balance ◽  
Nonlinear Equation ◽  
Electron Temperature ◽  
Dielectric Function ◽  
Thermal Conduction ◽  
Energy Balance Equation ◽  
Paraxial Approximation ◽  
Space Dependence ◽  
Electromagnetic Beams

AbstractIn this communication the interaction between two Gaussian electromagnetic beams in an ionic collision dominated plasma has been investigated, when the axes of the two beams are initially (z = 0) parallel along the z-axis in the xz plane; the beams are initially propagating in the z-direction. Taking into account the loss of electron energy by collisions and by thermal conduction, the energy balance equation for electrons has been solved to obtain the space dependence of the electron temperature and the dielectric function has been expressed as a function of the electron temperature; this expression for the dielectric function has been substituted in the wave equation and a solution of the resulting nonlinear equation obtained in the paraxial approximation. Second-order coupled ordinary differential equations have been obtained for the distance between the centers of the beams and the beam widths in the x- and y-directions as a function of the distance of propagation along the z-axis. The equations have been solved numerically for a range of parameters and a discussion of the results is presented for the case when the two beams have the same axial irradiance, frequency and width. From simple considerations it is seen that the beams attract each other when 2xo < wro and in this situation beams are close enough for the paraxial approximation to be valid.

scholarly journals Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

2017 ◽  
Vol 3 (2) ◽  
pp. 51-53
Author(s):  
Артем Гололобов ◽  
Artem Gololobov ◽  
Иннокентий Голиков ◽  
Innokentiy Golikov ◽  
Илья Варламов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Heat Fluxes ◽  
Winter Period ◽  
Time Interval ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Condi Tions ◽  
Field Lines ◽  
Heat Inflow

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances.

scholarly journals Physical Origins of Gas Motions in Galaxy Cluster Cores: Interpreting Hitomi Observations of the Perseus Cluster

2017 ◽  
Vol 849 (1) ◽  
pp. 54 ◽  
Author(s):  
Erwin T. Lau ◽  
Massimo Gaspari ◽  
Daisuke Nagai ◽  
Paolo Coppi
Keyword(s):  
Galaxy Cluster ◽  
Cluster Cores ◽  
Perseus Cluster

scholarly journals CHANDRAOBSERVATION OF A WEAK SHOCK IN THE GALAXY CLUSTER A2556

2012 ◽  
Vol 762 (1) ◽  
pp. 22 ◽  
Author(s):  
Zhenzhen Qin ◽  
Haiguang Xu ◽  
Jingying Wang ◽  
Yu Wang ◽  
Junhua Gu ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Weak Shock ◽  
The Galaxy

The vorticity jump across a shock in a non-uniform flow

1997 ◽  
Vol 341 ◽  
pp. 371-384 ◽  
Author(s):  
N. K.-R. KEVLAHAN
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
General Expression ◽  
Shock Intensity ◽  
Weak Shock ◽  
Uniform Flow ◽  
Vortex Sheets ◽  
Specific Heats ◽  
Vorticity Production ◽  
Weak Shocks

The vorticity jump across an unsteady curved shock propagating into a two-dimensional non-uniform flow is considered in detail. The exact general expression for the vorticity jump across a shock is derived from the gasdynamics equations. This general expression is then simplified by writing it entirely in terms of the Mach number of the shock MS and the local Mach number of the flow ahead of the shock MU.The vorticity jump is very large at places where the curvature of the shock is very large, even in the case of weak shocks. Vortex sheets form behind shock-shocks (associated with kinks in the shock front).The ratio of vorticity production by shock curvature to vorticity production by baroclinic effects is O(½(γ−1)M2U), where γ is ratio of specific heats, which is very small if the flow ahead of the shock is only weakly compressible. If, however, the tangential gradient along the shock of M2U is large then baroclinic production is significant; this is the case in turbulent flows with large gradients of turbulent kinetic energy ½M2U. The vorticity jump across a weak shock decreases in proportion to shock intensity if the flow ahead of the shock is rotational, rather than in proportion to the cube of shock intensity as is often assumed, and thus is not negligible. It is also shown that vorticity may be generated across a straight shock even if the flow ahead of the shock is irrotational. The importance of the contribution to the vorticity jump by non-uniformities in the flow ahead of the shock has not been recognized in the past.Examples are given of the vorticity jump across strong and weak shocks in a variety of flows exhibiting some properties of turbulence.

scholarly journals The weak shock in the core of the Perseus cluster

2008 ◽  
Vol 386 (1) ◽  
pp. 278-288 ◽  
Author(s):  
J. Graham ◽  
A. C. Fabian ◽  
J. S. Sanders
Keyword(s):  
Weak Shock ◽  
The Core ◽  
Perseus Cluster

AGN Jets, Bubbles, and Heat Pumps

2018 ◽  
Vol 14 (S342) ◽  
pp. 149-153
Author(s):  
Yi-Hao Chen ◽  
Sebastian Heinz
Keyword(s):  
Thermal Conduction ◽  
Thermal Evolution ◽  
Heat Pumps ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
Term Evolution ◽  
Radio Lobe ◽  
Low Entropy ◽  
Perseus Cluster

AbstractRadio-mode feedback from relativistic jets is one of the prominent heating mechanisms in clusters of galaxies. We present a long-term evolution of high-resolution MHD simulation of jets interacting with an environment modeled to represent the Perseus cluster. We investigate the thermodynamics of the ICM due to the gas motion triggered by the action of the jets and show that low-entropy gas is lifted efficiently in the wake of the inflating radio lobe. We look into the uplift mechanism and estimate the energy budget and the rate of thermal conduction. The redistribution of entropy suggests that heat conduction can play a more significant role in the thermal evolution of the cluster core in the presence of jets, which act effectively as a heat pump, thus heating the ICM more efficiently than jets would by themselves in an isentropic cluster.

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