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 2020
10/01/2020 @ 13:30 - 17:00
Utrecht, January 10th.
The meeting will take place in room 7.12, Buys Ballotgebouw, Princetonplein 5, Utrecht.
13:30 – 14:30: Talk by Zvonimir Vlah (CERN)
Title:Cosmological structure formation and the shapes in the sky
Understanding dark matter inhomogeneities and the corresponding tracers, like galaxies, on large cosmological scales, is considered one of the pillars of the standard cosmological model. Detailed understanding of these inhomogeneities is crucial for the interpretation of observational data from numerous current and future surveys. I will present recent developments in the analytic approaches of describing the formation of nonlinear structure in the universe based on the recent statistical field theory methods. In the second part, I will present a formalism based on the effective field theory methods to describe the statistics of shapes on the sky, and its application to the intrinsic alignments of galaxies.
14:30 – 15:00: Coffee Break
15:00 – 16:00: Talk by Florent Mertens(RUG)
Title: Observing the epoch of reionization and Cosmic Dawn with LOFAR and NenuFAR
Low-frequency observations of the redshifted 21cm line promise to open a new window onto the first billion years of the cosmic history, allowing us to directly study the astrophysical processes occurring during the Epoch of Reionization (EoR) and the Cosmic Dawn (CD). This exciting goal is challenged by the difficulty of extracting the feeble 21-cm signal buried under astrophysical foregrounds orders of magnitude brighter and contaminated by numerous instrumental systematics. Several experiments such as LOFAR, MWA, HERA and NenuFAR are currently underway aiming at statistically detecting the 21-cm brightness temperature fluctuations from the EoR and CD. While no detection is yet in sight, considerable progress has been made recently. In this talk I will review the latest development of the LOFAR Epoch of Reionization and NenuFAR Cosmic Dawn key science projects.
16:00 – 17:00: Talk by Suvodip Mukherjee(GRAPPA)
Title: A new window to Axion-Like Particles from the upcoming CMB experiments
Cosmic Microwave Background (CMB) is a powerful probe to the Universe which carries signatures of cosmic secrets over a vast range of redshifts. Along with spatial fluctuations, spectral distortions of CMB blackbody are also a rich source of cosmological information. In my talk, I will introduce a new kind of spectral distortion of CMB which can arise due to the conversion of CMB photons into Axion-Like Particles (ALPs) in the presence of an external magnetic field. This effect leads to both polarized and unpolarized spatially varying spectral distortion signal with a unique spectral shape when CMB photons undergo resonant and non-resonant conversion into ALPs in the presence of the magnetic field of Milky Way, galaxy clusters and voids. I will discuss the spatial structure of this distortion which can arise from Milky Way and galaxy clusters and will show its uniqueness from other known cosmological and astrophysical signals. I will present the first all-sky map of the ALPs distortion which is obtained using the data of Planck satellite and will discuss the capability of this new cosmological window to probe ALPs from the upcoming ground-based and space-based CMB experiments.