相关论文: On conduction, cooling flows and galaxy formation

Conduction may play an important role in reducing cooling flows in galaxy clusters. We analyse a sample of sixteen objects using Chandra data and find that a balance between conduction and cooling can exist in the hotter clusters (T > 5…

Chandra and XMM-Newton observations have confirmed the presence of large temperature gradients within the cores of many relaxed clusters of galaxies. Here we investigate whether thermal conduction operating over those gradients can supply…

We estimate the thermal conductivity of a weakly collisional magnetized plasma with chaotic magnetic field fluctuations. When the fluctuation spectrum extends over two or more decades in wave-vector, we find that thermal conduction is very…

Cluster cooling flow models that include both thermal conduction and AGN heating have lower overall mass cooling rates and simultaneously sustain density and temperature profiles similar to those observed with no ad hoc mass dropout. To…

Galaxy clusters host a large reservoir of diffuse plasma with radially-varying temperature profiles. The efficiency of thermal conduction in the intracluster medium (ICM) is complicated by the existence of turbulence and magnetic fields,…

We study the formation of clusters of galaxies using high-resolution hydrodynamic cosmological simulations that include the effect of thermal conduction with an effective isotropic conductivity of 1/3 the classical Spitzer value. We find…

Thermal conduction has been suggested as a possible mechanism by which sufficient energy is supplied to the central regions of galaxy clusters to balance the effect of radiative cooling. Here we present the results of a simulated,…

We have calculated lower limits for the global effective thermal conductivity in a sample of 165 Abell clusters. We assumed that cluster X-ray luminosity is compensated by a conductive heat flux which we then compare with an upper limit to…

We consider the impact of thermal conduction in clusters of galaxies on the (unmagnetized) interface between a cold gaseous cloud and a hotter gas flowing over the cloud (the so-called cold front). We argue that near the stagnation point of…

The gas temperature in the cores of many clusters of galaxies drops inward by about a factor of three or more within the central 100 kpc radius. The radiative cooling time drops over the same region from 5 or more Gyr down to below a few…

The gas temperature in the cores of many clusters of galaxies drops inward by about a factor of three or more within the central 100kpc radius. The radiative cooling time drops over the same region from 5 or more Gyr down to about 10^8 yr.…

Simulations of galaxy clusters have a difficult time reproducing the radial gas-property gradients and red central galaxies observed to exist in the cores of galaxy clusters. Thermal conduction has been suggested as a mechanism that can…

We study the possibility that a large fraction of the gas at temperatures of \~10^7 K in cooling flow clusters cools by heat conduction to lower temperatures, rather than by radiative cooling. We argue that this process, when incorporated…

We present a simple model of hot gas in galaxy clusters, assuming hydrostatic equilibrium and energy balance between radiative cooling and thermal conduction. For five clusters, A1795, A1835, A2199, A2390 and RXJ1347.5-1145, the model gives…

Recent observations by Chandra and XMM-Newton demonstrate that the central gas in "cooling flow" galaxy clusters has a mass cooling rate that decreases rapidly with decreasing temperature. This contrasts the predictions of a steady state…

The present structure of galaxies is governed by the radiative dissipation of the gravitational and supernova energy injected during formation. A crucial aspect of this process is whether the gas cools as fast as it falls into the…

X-ray observations of hot gas in galaxy clusters often show steeper temperature gradients across cold fronts -- contact discontinuities, driven by the differential gas motions. These sharp (a few kpc wide) surface brightness/temperature…

There is mounting observational evidence from Chandra for strong interaction between keV gas and AGN in cooling flows. It is now widely accepted that the temperatures of cluster cores are maintained at a level of 1 keV and that the mass…

In recent years evidence has accumulated suggesting that the gas in galaxy clusters is heated by non-gravitational processes. Here we calculate the heating rates required to maintain a physically motived mass flow rate, in a sample of seven…

We examine the role of thermal conduction and magnetic fields in cores of galaxy clusters through global simulations of the intracluster medium (ICM). In particular, we study the influence of thermal conduction, both isotropic and…