Constraining inflation and light relics with the DESI Lyman-alpha forest

by Jonás Chaves-Montero

Wednesday Mar 11, 2026, 1:00 PM → 2:00 PM Europe/Madrid

IFAE Seminar Room (In-person)

The Lyman-alpha forest refers to absorption lines in quasar spectra caused by neutral hydrogen in the intergalactic medium. In this talk, I present the cosmological analysis of line-of-sight correlations of the Lyman-alpha forest from the first data release of the Dark Energy Spectroscopic Instrument (DESI). Using a model calibrated on cosmological simulations with corrections for astrophysical contaminants and observational systematics, I analyze DESI measurements to set constraints on the shape of the linear matter power spectrum at z=3. The robustness of the results is assessed through extensive tests on simulated measurements and multiple analysis variations, with cosmological parameters blinded throughout. Then, I combine these measurements with CMB and large-scale structure data to set constraints on the sum of neutrino masses, light relics, and the inflation. While the addition of Lyman-alpha data does not significantly improve current limits on the sum of neutrino masses, it tightens constraints on the effective number of relativistic species and the shape of the primordial power spectrum.