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.
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Groningen Winter 2019
11/01/2019 @ 12:00 - 17:00
Groningen, January 11th 2019
The first THC meeting of the solar year will take place in Groningen. The venue is located downtown Groningen, at the Harmonie Building, room 1315.0036, Oude Kijk in Het Jatstraat 26.
Program
12:00 – 13:00: Talk by Filippo Vernizzi (Saclay)
Title: Dark Energy after GW170817
Abstract:
I will discuss some of the consequences of gravitational wave observations on (single field) dark energy and modified gravity. In particular, I will show that in some models gravitational waves can decay into dark energy and that the absence of this effect provides constraints on the space of parameters.
13:00 – 14:00: Lunch
14:00 – 15:00: Talk by Amina Helmi (Groningen University)
Title: New views on the Galaxy and its satellites from the Gaia space mission.
Abstract:
The recent 2nd data release of the Gaia mission took place in April 2018. It is currently revolutionizing our understanding of the Milky Way and its constituents. In this talk, I will highlight a few of the first results stemming from the analysis of this truly spectacular dataset. In particular, I will focus on what we have learned about the dynamics, mass distribution and assembly of the Milky Way and its satellites thus far.
15:00 – 15:30: Coffee Break
15:30 – 16:30: Talk by Sebastian Garcia-Saenz (IAP)
Title: Sidetracked Inflation
Abstract:
Heavy scalar fields can undergo an instability during inflation as a result of their kinetic coupling with the inflaton. This effect is known as the geometrical destabilization of inflation, as it is caused by the curvature of the internal manifold parametrized by the fields. The instability can drive the system away from its original path in field space into a new inflationary attractor, a scenario that we call “sidetracked inflation”. This talk will aim at describing the physics of this second phase and its observable consequences. I will show that the behavior of cosmological fluctuations can be understood by means of a single-field effective theory in which perturbations propagate with either a modified dispersion relation, a reduced speed of sound, or a speed of sound that is imaginary. The latter case is especially interesting as it leads to novel observational signatures, and in particular to unusual shapes in the non-Gaussianities.