Topic: cosmic microwave background

Lyman Page introduces temperature variations and polarization in the cosmic microwave background for researchers outside cosmology, explaining how these measurements underpin the standard cosmological model. He then considers what that model leaves unresolved, especially whether gravitational waves originating in the early Universe are detectable. The talk reviews the Simons Observatory’s experimental search for those primordial signals and its role in addressing this question. Online via Zoom Events in the John Bahcall Colloquium, hosted by the Institute for Underground Science at SURF. The

Petar Suman explores how higher-order statistics of the cosmic microwave background connect inflationary theory to observations. Although single-field inflation explains the origin of primordial fluctuations, its particle-physics mechanism remains uncertain. The first part examines the cosmological-collider programme: massive fields during inflation can leave oscillatory signatures in primordial non-Gaussianity, allowing measurements to constrain the masses and spins of early-universe particles. The second treats inflation as an open quantum system. An open effective field theory describes dis

Haruki Ebina discusses the marked power spectrum as a two-point approach to non-Gaussian density information, reducing the data-vector and covariance challenges of direct bispectrum analysis while retaining perturbative modelling. Recent work incorporates survey geometry, bringing applications to observations closer. Time permitting, he will also cover high-redshift DESI Run 2 cosmology and perturbative modelling of fast-radio-burst dispersion measures. Samuel Goldstein presents new constraints on fundamental physics from the cosmic microwave background and large-scale structure: axions using

JWST observations reveal sources earlier and brighter than anticipated. This talk examines their implications for cosmological and galaxy-formation models. It considers the unexpectedly numerous galaxies during the first few hundred million years, at redshifts above nine, and how cosmological clustering measurements can distinguish competing explanations. It then presents an initial empirical measurement of the dependence of star-formation variability, or burstiness, on galaxy mass, which may help explain the excess. Finally, it discusses tensions between JWST measurements of reionization and

Fraser Cain and Pamela L. Gay explore what cosmology can establish about the universe’s earliest history and where knowledge remains limited. The discussion covers inflation, the separation of forces, the emergence of particles and nuclei, and density fluctuations that seed later structure. Recombination and the cosmic microwave background lead into the dark ages, the first stars and reionization, with observations including JWST helping test models of the early universe. Pamela Gay is a senior scientist at the Planetary Science Institute. This Astronomy Cast episode was published on 14 Septem