Here below are listed the upcoming IFPU colloquia, usually taking place once a month on Fridays at 11am. Past colloquia from the current program can be found in the recent colloquia page, while older events can be found in the 2020-2021 and 2019-2021 pages.

Tom Abel (KIPAC, Stanford University)
Dark Matter Dynamics
Friday, July 1st, 2022, 11am – Aula D (old SISSA building) & streaming

Abstract We have a standard paradigm that quantitatively succeeds to describe the origin, formation and evolution of structure in the Universe. Dark matter is needed in this model to describe details of the Cosmic Microwave Background radiation, the appearance of high-redshift galaxies as well as many details of the clustering of galaxies. This broadly seems to works for the abundance of massive galaxy clusters, the prevalence of sheets, filaments and voids and the existence of ultra-faint dwarf galaxies. For Dark Matter made of an unknown particle that only interacts via gravity we have made predictions about how structure forms in the Universe using N-body techniques originally developed for plasma physics. These numerical investigations have led to many insights and enabled quantitative comparisons of the real and these simulated Universes. In this talk I describe and show visualizations from recently developed complimentary numerical methods that can describe the dark matter collisionless fluid in the continuum limit. These techniques follow three dimensional manifolds (“sheets”) as they evolve through the six dimensional phase space. The full geometry of the sheets is followed and consequently the noise of traditional N-body methods can be avoided completely. The caustics and detailed phase space structures inherent to the Hamiltonian dynamics of the particles are fully captured. These techniques also explain the origin of the shortcomings of traditional N-body such as artificial fragmentation evident in Warm Dark Matter models. These new approaches now also find application in modeling massive neutrinos in cosmology as well as applications in Laboratory Plasma Physics. The correspondence of the phase space sheet techniques  allow for high precision comparisons of simulations and analytical calculations promising an avenue to improve the analytic techniques and supersede standard perturbative approaches.

Contact: Matteo Biagetti
Tom Abel’s webpage