相关论文: Conduction and cooling flows
Effective heat conduction in a random variable magnetic field should be equal to one third of the Spitzer's value. Recent observations indicate that this heat conduction is sufficient to account for the bremsstrahlung in cooling X-ray…
The hot plasma permeating clusters of galaxies often shows a central peak in the X-ray surface brightness that is coincident with a drop in entropy. This is taken as evidence for a cooling flow where the radiative cooling in the central…
We report on a spatially resolved analysis of Chandra X-ray data on a nearby typical cooling flow cluster of galaxies 2A 0335+096, together with A 2199 for a comparison. As recently found in the cores of other clusters, the temperature…
We examine recent developments in the cluster cooling flow scenario following recent observations by Chandra and XMM-Newton. We show that the distribution of gas emissivity verses temperature determined by XMM-Newton gratings observations…
Recent Chandra observations of clusters of galaxies revealed the existence of a sharp ridge in the X-ray surface brightness where the temperature drops across the front. This front is called the cold front. We present the results of…
Analyses of Chandra's first images of cooling flow clusters find smaller cooling rates than previously thought. Cooling may be occurring preferentially near regions of star formation in central cluster galaxies, where the local cooling and…
The cluster of galaxies Abell 2146 is undergoing a major merger and is an ideal cluster to study ICM physics, as it has a simple geometry with the merger axis in the plane of the sky, its distance allows us to resolve features across the…
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…
We use Chandra data to derive a detailed gas temperature map of the nearby, hot, merging galaxy cluster A754. Combined with the X-ray and optical images, the map reveals a more complex merger geometry than previously thought, possibly…
We present a Chandra study of 38 X-ray luminous clusters of galaxies in the ROSAT Brightest Cluster Sample (BCS) that lie at z~0.15-0.4. We find that the majority of clusters at moderate redshift generally have smooth, relaxed morphologies…
In the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous "cooling flows" of gas sinking towards the cluster center, yet no such cooling…
Cooling flows are common in galaxy clusters which have cool cores. The soft X-ray emission below 1 keV from the flows is mostly absorbed by cold dusty gas within the central cooling sites. Further evidence for this process is presented here…
The cooling-flow problem is a long-standing puzzle that has received considerable recent attention, in part because the mechanism that quenches cooling flows in galaxy clusters is likely to be the same mechanism that sharply truncates the…
Chandra images of galaxy clusters have revealed a wealth of structure unseen by previous generations of low resolution X-ray observatories. In the cores of clusters, bright, irregular X-ray emission is now routinely seen within central…
We present Chandra gas temperature profiles at large radii for a sample of 13 nearby, relaxed galaxy clusters and groups, which includes A133, A262, A383, A478, A907, A1413, A1795, A1991, A2029, A2390, MKW4, RXJ1159+5531, and USGC S152. The…
Shortly after the first results of Chandra and XMM-Newton appeared, many researchers in the field abandoned the term "cooling flow clusters" in favor of the name "cool core clusters". This change, I argue, has been causing damage by…
We study the effects of externally imposed turbulence on the thermal properties of galaxy cluster cores, using three-dimensional numerical simulations including magnetic fields, anisotropic thermal conduction, and radiative cooling. The…
High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that the gas is not cooling to low temperatures at the predicted rates of hundreds to thousands of solar masses per year. X-ray images have revealed giant…
The universe's largest galaxies reside at the centers of galaxy clusters and are embedded in hot gas that, if left unchecked, would cool prodigiously and create many more new stars than are actually observed. Cooling can be regulated by…
Chandra X-ray observations revealed the presence of cold fronts (sharp contact discontinuities between gas regions with different temperatures and densities) in the centers of many, if not most, relaxed clusters with cool cores. We use…