Speaker
Description
The fundamental nature of Dark Matter (DM) remains an open problem in cosmology. Although LambdaCDM successfully describes it on cosmological scales, the model still faces some challenges on galactic scales. In the Superfluid Dark Matter (SFDM) approach, the DM particles behave as a cold, collisionless fluid on large scales, while forming a Bose-Einstein Condensate (BEC) on the scales of galaxies. Hence, the model manages to reproduce the successes of cold DM on the larger scales, while reproducing the results of MOND on galactic scales. In this work, we consider a cosmic string moving through a gas of SFDM and analyse how it affects the DM distribution. We look at two different cases: first, a cosmic string passing through an already condensed region, and second, through a region that is not yet condensed. In the former, the string moving at relativistic speeds induces a strong shock in the superfluid, leading to an increase in the temperature and thus destroying the BEC. In the latter, a wake of larger density is formed behind the string, and we study under which conditions a BEC can be formed in the virialized region of the wake. We obtain an upper bound on the mass of the DM particles on the order of 10eV, which is compatible with the SFDM model.
