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L. Grenacher

Publications and source records attributed to L. Grenacher.

7 recordsLinked to original sources
arXiv2000

Asphericity of galaxy clusters and Sunyaev-Zel'dovich effect

In this paper we investigate the Sunyaev-Zel'dovich (SZ) effect and the X-ray surface brightness for clusters of galaxies with a non-spherical mass distribution. In particular, we consider the influence of the shape and the finite extension of a cluster as well as of a polytropic thermal profile on the Compton parameter, the X-ray surface brightness and on the determination of the Hubble constant. We find that the the non-inclusion of such effects can induce errors up to 30 per cent in the various parameters and in particular on the Hubble constant value, when compared with results obtained under the isothermal, infinitely extended and spherical shape assumptions.

astro-ph↗
arXiv1999

Cold clouds in cooling flows

In many clusters of galaxies there is evidence for cooling flows which deposit large quantities of cool gas in the central regions. A fraction of this gas might accumulate as dense cool clouds. The aim of this communication is to discuss the minimum temperature achievable by clouds in cooling flows of different cluster of galaxies.

astro-ph↗
arXiv1999

Thermal equilibrium of cold clouds in PKS 0745-191

PKS 0745-191 is a powerful radio source with one of the largest known cooling flows (De Grandi, Molendi 1999). A fraction of the cool gas could accumulate into small molecular clouds. We studied the minimum temperature which can be reached by sub-clouds (resulting from the fragmentation of bigger clouds) in the cooling flow region.

astro-ph↗
arXiv1999

Molecular clouds in cooling flow cluster of galaxies

In many clusters of galaxies there is evidence for cooling flow in the central regions. A possibility is that a fraction of the gas forms cold molecular clouds. We investigate the minimum temperature which can be reached by clouds in cooling flows by computing the cooling function due to H2, HD and CO molecules. As an example, we determine the minimum temperature achievable by clouds in the cooling flow of PKS 0745-191.

astro-ph↗
arXiv1999

Thermal equilibrium of molecular clouds in cooling flow clusters

In many clusters of galaxies there is evidence for cooling flows in the central regions. The ultimate fate of the gas which cools is still unknown. A possibility is that a fraction of the gas forms cold molecular clouds. We investigate the minimum temperature which can be reached by clouds in cooling flows by computing the cooling function due to H2, HD and CO molecules. As an example, we determine the minimum temperature achievable by clouds in the cooling flows of the Centaurus, Hydra and PKS 0745-191 clusters. Our results suggest that clouds can reach very low temperatures - less than 10 K - which would explain the non-detection of CO in these clusters.

astro-ph↗