DESI Year 1 Results – Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations

We will present cosmological results from the measurement of baryon acoustic oscillations (BAO) in galaxy, quasar and Ly-α forest tracers from the first year of observations from the Dark Energy Spectroscopic Instrument (DESI). BAO provide robust measurements of the transverse comoving distance and Hubble rate, or their combination, relative to the sound horizon, in seven redshift bins from over 6 million extragalactic objects in the redshift range 0.1

With the first six redshift bins using over 5.7 million unique galaxy and quasar redshifts measured by DESI, the combined precision of the BAO is 0.52%. The seventh BAO measurement, at redshift z~2.3 is obtained over 0.4 million Ly-α forest spectra with their auto-correlation and their cross-correlation with the spatial distribution of 0.7 million quasars. The precision for this measurement is 1.1%.

Then we will present the cosmological interpretation of these BAO measurements, in the framework of the standard flat ΛCDM cosmological model. In particular we will show cosmological constraints on the Hubble parameter H₀ and on the sum of neutrino mass. Finally, we will extend the interpretation to models with a constant dark energy equation of state and even to those with a time-varying dark energy equation of state.

Contact local & organisation : Vanina RUHLMANN-KLEIDER, François BRUN & Frédéric GALLIANO

DAp DPhP