Theoretical Cosmology meetings
To actively encourage the field of theoretical cosmology and to set an informal stage for the exchange of ideas, the Dutch theoretical cosmology community organizes Friday afternoon meetings approximately 6 times a year — usually on the first Friday of the month. The meetings typically start in the afternoon with a main speaker, followed by a short break to continue with another seminar or journal club discussion on some topic of current interest. We end the afternoon with drinks. The supporting institutes in Leiden, Amsterdam, Groningen, Utrecht where recently joined by the strings and cosmology group in Leuven and take turns in hosting the event.
- This event has passed.
Utrecht Fall 2015
02/10/2015 @ 14:00 - 18:00
14h00 – 15h00
Mathias Garny (CERN)
UV dependence of the large scale structure power spectrum
We discuss a non-perturbative equation for the power spectrum of large-scale density perturbations at long wavelength. It is based on equal-time consistency relations and an operator product expansion scheme, and encapsulates the dependence on UV modes into a number of response functions in a modified cosmology. We argue that they depend only weakly on the short-scale perturbation spectrum, and discuss implications for the leading coefficients in the effective field theory approach to large-scale structure formation.
15h45 – 16h30
Cora Uhlemann (LMU, Munich)
Large scale structure formation with the Schrödinger method
When describing large-scale structure formation one is interested in the dynamics of a large collection of dark matter particles that interact only gravitationally. Even though this problem seems quite simple from a conceptual point of view, no sufficiently general solution of the underlying equation, the Vlasov-Poisson equation, is known. Therefore one usually has to resort to N-body simulations which tackle the problem numerically. Analytical methods are based on the dust model which describes cold dark matter as a pressureless fluid characterized by density and velocity. This model works up to the quasi-linear regime but eventually fails when multiple streams form that are important for halo formation but lead to singularities. We present the so-called Schrödinger method, based on the Wigner distribution obtained from a wave function fulfilling the Schroedinger-Poisson equation, as a replacement for the dust model. We show that its evolution equation approximates the Vlasov equation in a controlled way, cures the shell-crossing singularities and is able to describe regions of multi-streaming. We explain how the Schroedinger method thereby incorporates higher cumulants self-consistently and closes the cumulant hierarchy instead of truncating it.
17h00 – 18h00 Drinks