We calculate the stellar energy loss due to neutrino-pair production in e + e − annihilation in the context of a 331 model, a left-right symmetric model and a simplest little Higgs model in a way that can be used in supernova calculations. We also present some simple estimates which show that such process can act as an efficient energy loss mechanism in the shocked supernova core.We find that the stellar energy loss is almost independent on the parameters of the models in the allowed range for these parameters. This work complements other studies on the stellar energy loss rate in e + e − annihilation.
We calculate the torque on galaxies in clusters due to gravity and to dynamical friction forces in order to study the possible origin of small-scale alignment effects as the result of interactions with their environment. The equation of motion for the position angle of a galaxy is derived by using a simple model. We find that weak radial alignment effects can be produced by this mechanism involving only the most massive galaxies. We also introduce a dependence on the cluster eccentricity to our equations in order to explore the alignment of galaxies with the cluster's major axis. We find that in the inner regions of high eccentricity clusters, alignments of massive galaxies with the cluster's major axis dominate over the radial ones. This mechanism could account for the observed alignment effects of the most massive galaxies with the major axis of their host cluster. Our results suggest that dynamical friction is a viable generator of alignment only for the most massive cluster galaxies. For the observed alignments of normal galaxies a primordial origin has to be explored.
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