Bachelor’s / Master’s Thesis Project in Astronomy

Gravitational millilensing by cold dark matter subhalos and globular clusters (15/30/45 hp)

One of the so far unconfirmed predictions of the cold dark matter (CDM) scenario is that each galaxy-sized dark matter halo should contain large numbers of subhalos in the dwarf-galaxy mass range. These subhalos do not appear to correspond to luminous structures, since the Milky Way would then be surrounded by an order of magnitude more satellite galaxies than observed, provided that each subhalo hosts a luminous dwarf galaxy. One way out of this dilemma is to assume that most of these low-mass halos instead correspond to so-called dark galaxies, i.e. objects of dwarf-galaxy mass which either do not contain baryons or in which the baryons have formed unusually few stars. Gravitational lensing may in principle offer a route to detecting subhalos that are too dark to be identified through other means, but this requires that the lensing signal from subhalos dominates over that of mundane, baryonic halo objects like globular clusters. In this project, the feasibility of a millilensing search for CDM subhalos will be critically investigated through a direct comparison of the lensing properties of subhalos and globulars.

Supervisor: Erik Zackrisson
Co-supervisor: Teresa Riehm

Please contact Erik Zackrisson, ez(at)astro.su.se, for more information!