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.
Utrecht Winter 2022
December 9 @ 13:00 - 17:00
Utrecht, December 9th.
In the following the program of the day:
13:00 CET — Welcome and coffee
13:30-14:30 CET — Talk by Bogumila Swiezewska (Warsaw University)
Title: Supercooled Phase Transition in the Early Universe: Gravitational Waves, Dark Matter and Renormalisation
We present an updated analysis of the first-order phase transition associated with symmetry breaking in the early Universe in a classically scale-invariant model extended with a new SU(2) gauge group. Including recent developments in understanding supercooled phase transitions, we compute all of its characteristics and constrain the parameter space. We then predict gravitational-wave spectra generated during this phase transition. Next, by computing the signal-to-noise ratio, we conclude that this model is well testable (and falsifiable) with LISA. We also provide predictions for the relic dark matter abundance. It is consistent with observations in a rather narrow part of the parameter space, as we exclude the so-called supercool dark matter scenario based on an improved description of percolation and reheating after the phase transition. Finally, we pay special attention to renormalisation-scale dependence of the results. Even though our main results are obtained with the use of renormalisation-group improved effective potential, we also present the outcome of a fixed-scale analysis. It proves that the dependence on the scale is not only qualitative but also quantitative. Based on arXiv:2210.07075.
14:30-14:45 CET — Break
14:45-15:45 CET — Talk by Alex Eggemeier (Bonn University)
Title: Cosmological constraints from two- and three-point galaxy clustering
Analyses of two-point clustering statistics have become the conventional instrument for inferring cosmological constraints from galaxy surveys. It is well known, however, that the observed distribution of galaxies is strongly non-Gaussian, which implies that significant additional information is locked up in its higher-order clustering moments. Extracting that information in a robust manner remains a challenging task, but is essential for maximising the scientific returns from the next generation of galaxy surveys. In this talk I will present how we prepare for a joint analysis of two- and three-point clustering in Euclid and in order to illustrate one of the challenges I will discuss the modelling of redshift-space distortions. By studying mock galaxy catalogues at Euclid sensitivity, I will demonstrate how an improved description of the real to redshift-space mapping leads to a consistent modelling over a wider range of scales, which turns out to be crucial for leveraging the constraining power of the three-point function.
15:45-16:00 CET — Break
16:00-17:00 CET — Talk by Anna Balaudo (Leiden University)
Title: Prospects for testing late-time cosmology with weak leaning of gravitational waves and galaxy surveys
With the advent of next generation gravitational waves (GW) detectors and galaxy surveys, significant effort has been put in finding new ways of constraining cosmological parameters with always increasing precision. I will present our lates work, in which we investigate the synergy of upcoming galaxy surveys and GW experiments in constraining late-time cosmology, examining the cross-correlations between the weak lensing of gravitational waves (GW-WL) and the galaxy fields. We focus on LCDM and scalar-tensor cosmologies, using the Effective Field Theory formalism as a unifying language; without focusing on a specific GW detector configuration, we benchmark the requirements for the high precision measurement of cosmological parameters by considering several scenarios, varying the number of detected GW events and the uncertainty on the inference of the source luminosity distance and redshift. Though some of the configurations investigated in this work are likely beyond the observational capabilities of currently planned individual GW detectors, we show nonetheless that – provided that enough statistics of events can be accumulated – GW-WL offers the potential to become a cosmological probe complementary to LSS surveys, particularly for those parameters that cannot be constrained by other GW probes such as standard sirens.
17:00 CET — Borrel