First author: Moritz Haslbauer
The James Webb Space Telescope (JWST) discovered several luminous high-redshift galaxy candidates with stellar masses of $M_{} \gtrsim 10^{9} , \rm{M_{\odot}}$ at photometric redshifts $z_{\mathrm{phot}} \gtrsim 10$ which allows to constrain galaxy and structure formation models. For example, Adams et al. identified the candidate ID 1514 with $\log_{10}(M_{}/M_{\odot}) = {9.8}{-0.2}^{+0.2}$ located at $z{\mathrm{phot}} = 9.85_{-0.12}^{+0.18}$ and Naidu et al. found even more distant candidates labeled as GL-z11 and GL-z13 with $\log_{10}(M_{}/M_{\odot}) = 9.
First author: William Giarè
Inflationary gravitational waves, behaving as additional radiation in the Early Universe, can increase the effective number of relativistic species ($N_{\rm eff}$) by a further correction that depends on the integrated energy-density in gravitational waves over all scales. This effect is typically used to constrain (blue-tilted) models of inflation in light of the bounds resulting from the Big Bang Nucleosynthesis. In this paper, we recompute this contribution, discussing some caveats of the state-of-the-art analyses.
Kensuke Akita
We review the distortions of spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early universe. We solve integro-differential kinetic equations for the neutrino density matrix, including vacuum three-flavor neutrino oscillations, oscillations in electron and positron background, a collision term and finite temperature corrections to electron mass and electromagnetic plasma up to the next-to-leading order $\mathcal{O}(e^3)$. After that, we estimate the effects of the spectral distortions in neutrino decoupling on the number density and energy density of the Cosmic Neutrino Background (C$ν$B) in the current universe, and discuss the implications of these effects on the capture rates in direct detection of the C$ν$B on tritium, with emphasis on the PTOLEMY-type experiment.
Cristian Joana
Cosmic inflation is arguably the most favoured paradigm of the very early Universe. It postulates an early phase of fast, nearly exponential, and accelerated expansion. Inflationary models are capable of explaining the overall flatness and homogeneity of today’s Universe at large scales. Despite being widely accepted by the physics community, these models are not absent from criticism. In scalar field inflation, a necessary condition to begin inflation is the requirement of a Universe dominated by the field’s potential, which implies a subdominant contribution from the scalar field dynamics.
Andrew Cheek
Many cosmological phenomena lead to the production of primordial black holes in the early Universe. These phenomena often create a population of black holes with extended mass and spin distributions. As these black holes evaporate via Hawking radiation, they can modify various cosmological observables, lead to the production of dark matter, modify the number of effective relativistic degrees of freedom, $N_{\rm eff}$, source a stochastic gravitational wave background and alter the dynamics of baryogenesis.
Timothy Cohen
Fluctuations play a critical role in cosmology. They are relevant across a range of phenomena from the dynamics of inflation to the formation of structure. In many cases, these fluctuations are coarse grained and follow a Gaussian distribution as a consequence of the Central Limit Theorem. Yet, some classes of observables are dominated by rare fluctuations and are sensitive to the details of the underlying microphysics. In this paper, we argue that the Large Deviation Principle can be used to diagnose when one must to appeal to the fundamental description.
