17-22 July 2016
Master Cutlers Hall
Europe/London timezone

Bose-Einstein Condensation of Dark Matter Axions

19 Jul 2016, 11:20
20m
Venue: Cutlers' Main Hall (First Floor); Chair: Karl van Bibber; Session Managers: David Woodward & Jost Migenda ()

Venue: Cutlers' Main Hall (First Floor); Chair: Karl van Bibber; Session Managers: David Woodward & Jost Migenda

Speaker

Prof. Pierre Sikivie (University of Florida)

Description

It has long been known that axions produced by vacuum realignment during the QCD phase transition in the early universe form a cold degenerate Bose gas and are a candidate for the dark matter. More recently it was found that dark matter axions thermalize through their gravitational self-interactions and form a Bose-Einstein condensate (BEC). On timescales long compared to their rethermalization time scale, almost all the axions go to the lowest energy state available to them. In this behaviour they differ from the other dark matter candidates. Axions accreting onto a galactic halo fall in with net overall rotation because almost all go to the lowest energy available state for given angular momentum. In contrast, the other proposed forms of dark matter accrete onto galactic halos with an irrotational velocity field. The inner caustics are different in the two cases. I'll argue that the dark matter is axions, at least in part, because there is observational evidence for the type of inner caustic produced by, and only by, an axion BEC.

Primary author

Prof. Pierre Sikivie (University of Florida)

Presentation Materials

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