On Einstein clusters as galactic dark matter halos - General Relativity and Quantum CosmologyReport as inadecuate




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Abstract: We consider global and gravitational lensing properties of the recentlysuggested Einstein clusters of WIMPs as galactic dark matter halos. Beingtangential pressure dominated, Einstein clusters are strongly anisotropicsystems which can describe any galactic rotation curve by specifying theanisotropy. Due to this property, Einstein clusters may be considered as darkmatter candidates. We analyse the stability of the Einstein clusters againstboth radial and non-radial pulsations, and we show that the Einstein clustersare dynamically stable. With the use of the Buchdahl type inequalities foranisotropic bodies, we derive upper limits on the velocity of the particlesdefining the cluster. These limits are consistent with those obtained fromstability considerations. The study of light deflection shows that thegravitational lensing effect is slightly smaller for the Einstein clusters, ascompared to the singular isothermal density sphere model for dark matter.Therefore lensing observations may discriminate, at least in principle, betweenEinstein cluster and other dark matter models.



Author: C. G. Boehmer, T. Harko

Source: https://arxiv.org/



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