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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Utrecht Winter 2022

14/01/2022 @ 13:00 - 17:00

Utrecht, January 14th.

This meeting will take place via remote connection through Microsoft Teams. Here the information for connecting:

Time: January 14, 2022 01:00 PM Amsterdam Time

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13:00-14:00 CET: Talk by Giorgio Orlando (RUG)

Title: Probing inflation with cross-correlations


Throughout the years, the cosmic microwave background (CMB) has provided important contributions in shaping the standard cosmological model, becoming a crucial observational tool in modern cosmology. In particular, in this era of high-precision cosmology, CMB observations allow us to put constraints on the physics of inflation, where the first cosmological perturbations originated.
However, because we have yet to detect a primordial signature of gravitational waves and CMB anisotropies probe inflation only on the largest cosmological scales, a variety of models beyond the simplest, slow-roll single-field scenarios, are unconstrained. In this presentation I will briefly review this aspect, and show two examples on how cross-correlations between CMB primary anisotropies and alternative cosmological tracers can help probing non-conventional inflationary scenarios through primordial squeezed bispectra.

14:00-14:15 CET: Break

14:15-15:15 CET: Talk by Johannes Noller (ICG Portsmouth)

Title: Testing gravity on all scales 


Recent years have seen great progress in probing gravitational physics on a vast range of scales, from the very largest cosmological scales to those associated with high energy particle physics. In this talk I will focus on how we can use these different systems synoptically to learn more about dark energy. Specifically, I will discuss the interplay of dark energy constraints from the following systems: gravitational waves emitted by binary systems, the cosmic microwave background, large scale structure, and novel theoretical bounds on the behaviour of gravity (ranging from purely classical stability requirements to so-called ‘positivity’ priors).

15:15-15:30 CET: Break

15:30-16:30 CET: Joint-talk by Alex Amon (Cambridge) and Jessie Muir (Perimeter)

Title of Alex Amon’s talk: Cosmology from weak lensing – is lensing low?

Abstract of Alex Amon’s talk:

I will present the cosmological weak lensing and clustering results from the Dark Energy Survey (DES) using its first three years of data taken using the Dark Energy Camera on the 4m Blanco telescope at CTIO. This analysis spans the full DES footprint, more than 4000 sq. deg. of sky, with the final shear catalogue containing more than 100 million galaxies in riz photometric bands, constituting the most powerful weak lensing dataset to date. The comparison of DES cosmological constraints on dark matter and dark energy from WL and LSS in the low-redshift Universe to CMB constraints provides an unprecedented test of the standard cosmological model, across high and low redshift. I will mention the main challenges that our analysis is susceptible to, and the summarise the approach to account for these and deliver robust cosmological constraints. Finally, I’ll summarise new developments necessary to exploit the data from DES Legacy and Rubin Observatory.

Title of Jessie Muir’s talk: Extending DES analyses to models beyond LCDM

Abstract of Jessie Muir’s talk:

I will build on Alex’s presentation to give an overview of efforts within DES to search for physics beyond our cosmological standard model. My main focus will be on the combined analysis of galaxy clustering and weak lensing, and particularly on ongoing efforts to use DES Year 3 data to constrain a set of extended cosmological models including a time-dependent dark energy equation of state, modified gravity, and sterile neutrinos. To provide context I’ll highlight some previously published results based on the first year of DES data, as well as some of the challenges associated with performing a robust beyond-LCDM analyses as measurements become increasingly precise.

16:30 CET: social virtual borrel and socializing


13:00 - 17:00
Event Category:


Microsoft Teams meeting


Tomislav Prokopec
Elisa Chisari