13-18 December 2015
International Conference Centre Geneva
Europe/Zurich timezone

Dark matter ultracompact minihalos and the small-scale early Universe

16 Dec 2015, 17:05
Level 2, Room 7&8 (International Conference Centre Geneva)

Level 2, Room 7&8

International Conference Centre Geneva

17 Rue de Varembé, 1211 Geneva


Hamish Clark (University of Sydney)


In this talk I will discuss recent efforts to detect dark matter 'ultracompact minihalos' (UCMHs), including a novel utilisation of gravitational time-delay lensing with pulsars. Recently proposed as a type of small-scale dark matter structure, UCMHs are formed from large overdensities in the very early Universe. They have been shown to be able to persist through to the present day, providing a unique opportunity to investigate the conditions of the Universe at early times. I will present recent results constraining the number of UCMHs within the Milky Way, and discuss their implied limits on three processes that lead to their formation: increased primordial power on small scales, primordial non-Gaussianity, and the presence of high-tension cosmic string loops.

Primary author

Hamish Clark (University of Sydney)


Prof. Geraint Lewis (University of Sydney) Dr Pat Scott (Imperial College London)

Presentation Materials