Seminar 16.09.2013 – Shape of clusters of galaxies as a probe of screening mechanisms in modified gravity
University of Oslo
Facultat de Física
Several extensions of General Relativity and high energy physics intend to explain the accelerated expansion of the universe by including scalar fields as extra degrees of freedom. At present, there is a broad spectrum of theories that fulfill this requirement and at the same time have no effects at very small scales, which makes the able to pass solar system tests. In order to know if these scalar fields indeed exist, we need to find predictions at intermediate scales in between those involved in the expansion of the universe and the solar system (i.e. galaxies and galaxy clusters scales). I will summarize some of the properties of two particular families of scalar-tensor theories (symmetron and chameleon models) and I will show why observations of the shape of dark matter halos could help to disentangle between them.