Le 21 septembre 2018
De 10h30 à 12h00
Adriano Agnello
ESO
Much of today’s Universe is “dark”. In the concordance cosmological scenario, Dark Energy is the likely culprit for the (observed) accelerated expansion of the Universe, while Dark Matter governs the motions of stars in galaxies and of galaxies in clusters (besides fitting beautifully the observed peaks in the CMB). Despite this general consensus, several open questions remain. The answers rely on accurate measurements of distances and masses. In this talk, I will illustrate some recent progress and prospects for the era of Extremely Large Telescopes (ELTs). The first part will cover recent advances in cosmography. Specifically, I will show our recent H0 measurements from time-delay lensing, which give one-step measurements of cosmological distances. The aim of 1% uncertainties on H0, within the plans of the H0LiCOW collaboration, will allow us to identify possible discrepancies with CMB experiments, determine the Equation of State of Dark Energy and whether the Universe is (not) flat. In the second part of the talk, I will address the issue of weighing Dark Matter in galaxies. I will start from the case of the “galaxy lacking dark matter”, argue that its dark halo is actually not surprising, and what future prospects are for weighing faint and far dwarf galaxies with ELT facilities. I will then move to galaxies at z~0.5, measured on a homogeneous sample of gravitational lenses (some newly discovered), and show how we can push this to smaller lenses with future surveys and telescopes. Even though everything is presented in the context of concordance (LCDM) cosmology, most of the above can be investigated also within theories of modified gravity.