Cosmology seminars

This seminar derives how dark-matter halo density profiles emerge from hierarchical assembly using the Boltzmann–Poisson equations for a coarse-grained distribution of subhalos in an expanding universe. An exact self-similar solution relates density slope γ to mass growth M proportional to tˢ through γ = 6/(s + 2). Initial collapse gives a prompt γ = 3/2 cusp; hierarchical accretion recovers the Syer–White relation and an attractive n = −2 fixed point with γ = 1; stalled accretion approaches γ = 3. These stages provide a dynamical account of the inner and outer Navarro–Frenk–White profile.

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 Atacama Cosmology Telescope observations, primordial non-Gaussianity, multi-field inflation using DESI, and component-separated temperature, polarization, thermal Sunyaev–Zeldovich and kinetic Sunyaev–Zeldovich maps from early Simons Observatory data. Speakers: Haruki Ebina, UC Berkeley, and Samuel Goldstein, Columbia University. Organized by Stanford KIPAC. Tuesday 29 September 2026, 10:40–11:30 America/Los_Angeles (PDT). Online via Zoom using Join the zoom meeting on the official event page. The organizer lists the intended audience as Faculty/Staff, Members and Students. Only remote attendance is verified for this listing.