Possible explanations for the diversity of galaxy rotation curves

by Kyle Oman (Durham)

Tuesday 12 Nov 2019, 15:00 → 17:00 Europe/Berlin

SR2 (Bldg 2A)

The cusp-core problem is summarized as the tension between the observation that (some) galaxies have internal dynamics suggestive of a central region of constant dark matter density (core) and the result from N-body simulations that dark matter density profiles are expected to rise steeply (rho~r^-1) toward the centres of galaxies (cusp). This tension may be resolved (i) by allowing for the possibility that violent processes such as supernovae may drive fast flows of gas which couple dynamically to the dark matter to transform a cusp into a core; (ii) allowing that the dark matter is not purely cold and collisionless such as to limit the central density; (iii) allowing for departures from general relativity and/or (iv) accounting for possibly severe systematic errors in the modelling of the internal dynamics of galaxies. I will briefly discuss each of these before going further in depth on (iv) by comparing the "observationally" inferred rotation curves of simulated galaxies with their true circular velocity curves.