First detection of the BAO signal from early DESI data

DESI Collaboration, Seshadri Nadathur

Research output: Contribution to journalArticlepeer-review


We present the first detection of the baryon acoustic oscillations (BAO) signal obtained using unblinded data collected during the initial two months of operations of the Stage-IV ground-based Dark Energy Spectroscopic Instrument (DESI). From a selected sample of 261,291 Luminous Red Galaxies spanning the redshift interval 0.4 < z < 1.1 and covering 1651 square degrees with a 57.9% completeness level, we report a ~5σ level BAO detection and the measurement of the BAO location at a precision of 1.7%. Using a Bright Galaxy Sample of 109,523 galaxies in the redshift range 0.1 < z < 0.5, over 3677 square degrees with a 50.0% completeness, we also detect the BAO feature at ~3σ significance with a 2.6% precision. These first BAO measurements represent an important milestone, acting as a quality control on the optimal performance of the complex robotically-actuated, fiber-fed DESI spectrograph, as well as an early validation of the DESI spectroscopic pipeline and data management system. Based on these first promising results, we forecast that DESI is on target to achieve a high-significance BAO detection at sub-percent precision with the completed 5-year survey data, meeting the top-level science requirements on BAO measurements. This exquisite level of precision will set new standards in cosmology and confirm DESI as the most competitive BAO experiment for the remainder of this decade.
Original languageEnglish
Pages (from-to)5406–5422
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Early online date1 Sept 2023
Publication statusPublished - 1 Nov 2023


  • galaxies: statistics
  • cosmology: large-scale structure of Uni verse, observ ations, dark energy
  • methods: data analysis, statistical
  • UKRI
  • STFC
  • ObsCos_highlight

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