First cosmology results from BAO in the Dark Energy Spectroscopic Instrument (DESI)

28.06.2024 10:00 – 11:00

I will present a summary of the measurements of Baryon Acoustic Oscillations in the data release 1 (DR1) of the DESI survey and the interesting cosmological results derived from them. We use redshifts to over 6 million extragalactic objects - a factor of 3x used by SDSS! - to measure BAO and use this to determine the expansion rate of the Universe over the last 11 billion years, in seven redshift bins in the range 0.1 < z < 4.2. Within a flat Lambda cold dark matter (LCDM) background model, DESI results are consistent with those from the CMB, and give a precision of 1% or better on the Hubble constant H_0. We derive an upper limit on the sum of the neutrino masses of M_nu < 0.072 eV (95% confidence): I will explain how this limit depends on priors and assumptions about the background expansion. But most interestingly, we find tentative evidence for a time varying dark energy, with the combination of DESI BAO, CMB and type Ia supernovae rejecting a cosmological constant with significances of between 2.5 and 3.9 sigma, depending on the dataset used.

Lieu

Bâtiment: Ecole de Physique

Stueckelberg-009

entrée libre