Related papers: Heating Cooling Flows with Weak Shock Waves
In order to find the conditions which determine whether X-Ray hot gas in galaxy groups (intragroup gas; IGG) is heated externally or internally, we investigate the evolution of blast waves in galaxy groups growing on a hierarchical…
In conventional models of galactic and cluster cooling flows widespread cooling (mass dropout) is assumed to avoid accumulation of unacceptably large central masses. However, recent XMM observations have failed to find spectral evidence for…
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…
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 investigate the origin of the variation of the gas mass fraction in the core of galaxy clusters, which was indicated by our work on the X-ray fundamental plane. The adopted model supposes that the gas distribution characterized by the…
The X-ray emission in many clusters of galaxies shows a central peak in surface brightness coincident with a drop in temperature. These characterize a cooling flow. There is often a radio source also at the centre of such regions. Data from…
We present the statistical analysis of X-ray surface brightness and gas density fluctuations in cool cores of ten, nearby and bright galaxy clusters that have deep Chandra observations and show observational indications of radio-mechanical…
The standard cooling flow model has predicted a large amount of cool gas in the clusters of galaxies. The failure of the Chandra and XXM-Newton telescopes to detect cooling gas (below 1-2 keV) in clusters of galaxies has suggested that some…
In addition to lines originating in a soft phase at ~0.8 keV and to cold molecular clouds, the X-ray spectra from the Galactic center region also exhibit properties similar to those of a diffuse, thin, very hot plasma at 8 keV on a scale of…
We present preliminary results of the XMM-Newton 50 ksec observation of the Perseus cluster. The global east/west asymmetry of the gas temperature and surface brightness distributions, approximately aligned with the chain of bright…
It has been proposed that the cool cores of galaxy clusters are stably heated by cosmic rays (CRs). If this is the case, radio mini-halos, which are often found in the central regions of cool core clusters, may be attributed to the…
The diffuse plasma inside clusters of galaxies has X-ray emitting temperatures of a few keV. The physical mechanisms that heat this intracluster medium (ICM) to such temperatures include the accretion shock at the periphery of a galaxy…
X-ray observations of clusters of galaxies reveal the presence of edges in surface brightness and temperature, known as "cold fronts". In relaxed clusters with cool cores, these commonly observed edges have been interpreted as evidence for…
A new model for cooling flows in X-ray clusters, capable of naturally explaining salient features observed, is proposed. The only requirement is that a significant relativistic component, in the form of cosmic rays (CR), be present in the…
The radiative cooling time of the hot gas at the centres of cool cores in clusters of galaxies drops down to 10 million years and below. The observed mass cooling rate of such gas is very low, suggesting that AGN feedback is very tightly…
In the centers of many galaxy clusters, the hot ($\sim$10$^7$ K) intracluster medium (ICM) can become dense enough that it should cool on short timescales. However, the low measured star formation rates in massive central galaxies and…
It is now generally agreed that some process prevents the diffuse gas in galaxy clusters from cooling significantly, although there is less agreement about the nature of this process. I suggest that cluster gas may be heated by a natural…
The gas in galaxy clusters is heated by shock compression through accretion (outer shocks) and mergers (inner shocks). These processes additionally produce turbulence. To analyse the relation between the thermal and turbulent energies of…
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…
Many galaxy clusters pose a "cooling-flow problem", where the observed X-ray emission from their cores is not accompanied by enough cold gas or star formation. A continuous energy source is required to balance the cooling rate over the…