DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest

We present the measurement of Baryon Acoustic Oscillations (BAO) from theLyman-α (Lyα) forest of high-redshift quasars with the first-yeardataset of the Dark Energy Spectroscopic Instrument (DESI). Our analysis usesover 420 000 Lyα forest spectra and their correlation with thespatial distribution of more than 700 000 quasars. An essential facet ofthis work is the development of a new analysis methodology on a blindeddataset. We conducted rigorous tests using synthetic data to ensure thereliability of our methodology and findings before unblinding. Additionally, weconducted multiple data splits to assess the consistency of the results andscrutinized various analysis approaches to confirm their robustness. For agiven value of the sound horizon (r_d), we measure the expansion at z_=2.33 with 2% precision, H(z_ eff) = (239.2 ± 4.8) (147.09  /r_d) km/s/Mpc. Similarly, we present a 2.4% measurement of thetransverse comoving distance to the same redshift, D_M(z_ eff) = (5.84± 0.14) (r_d/147.09  Mpc) Gpc. Together with other DESI BAOmeasurements at lower redshifts, these results are used in a companion paper toconstrain cosmological parameters.

Further reading#

• Access Paper in arXiv.org