Angular Baryon Acoustic Oscillations with DESI DR1
Abstract
We present the angular BAO analysis using DESI DR1 data as a complementary approach to DESI's primary 3D BAO analysis. We perform the analysis using the two-point angular correlation function w(θ) in tomographic redshift shells of δz = 0.02, 0.05, spanning the redshift range 0.4 < z < 2.1 using the DESI tracers: LRG1, LRG2, LRG3+ELG1, ELG2 and QSO. The main benefit is that it requires no fiducial cosmology to convert redshifts into distances and yields a direct measurement of the transverse dilation parameter α⊥(z). We fit each tracer with a single shared α⊥(z) using templates constructed in a fiducial cosmology and a mock-based covariance from 1000 EZmock realisations. We measure α⊥ to $2.5$ -- 4.2% precision in each tracer bin. Compared to the DM/rd measurements obtained from the DESI DR1 3D analysis for the same tracers, our results are consistent within the statistical precision. We find no evidence for a shift in the transverse BAO scale between the 2D and 3D analyses. Flat ΛCDM fits to α⊥(z) alone give Ωm = 0.198+0.045−0.068, 1.6σ below the DESI 3D value, and the pull is dominated by the z =1.49 QSO bin, whose α⊥(z=1.49)=1.058±0.028 sits ∼ 2σ above the fiducial. Restricting to LRGs and ELGs only, our Ωm and H0 rd agree with the 3D transverse-only fit over the same bins to better than 0.1σ. With an additional BBN prior, the full 2D sample gives H0 = 63.9+1.9−3.3 km s−1 Mpc−1. This pipeline is implementable on forthcoming DESI data releases, where the increase in volume and sampling density will determine if the QSO offset persists and will also tighten 2D BAO constraints.
Related
- Joint Constraints on the Hubble Constant and Cosmic Baryon Density from Localized Fast Radio Bursts and DESI DR2 Baryon Acoustic Oscillations
- Model-independent and reconstruction-free evidence for cosmic acceleration from DESI baryon acoustic oscillations
- Baryon Acoustic Oscillations from the C iv Forest with DESI DR2
- A Unified Tracer Analysis of DESI DR2 Baryon Acoustic Oscillations
- Revisiting self-interacting dark matter with DESI DR2 baryon acoustic oscillation observations
BibTeX
@misc{paopiamsap2026angular,
title = {{Angular Baryon Acoustic Oscillations with DESI DR1}},
author = {Anya Paopiamsap and Juan Mena-Fernández and Héctor Gil-Marín and Licia Verde},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10215},
eprint = {2610.10215},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05834674v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Angular Baryon Acoustic Oscillations with DESI DR1
AU - Anya Paopiamsap
AU - Juan Mena-Fernández
AU - Héctor Gil-Marín
AU - Licia Verde
PY - 2026
DA - 2026/10/07
PB - HAL
DO - 10.48550/arxiv.2610.10215
UR - https://hal.science/hal-05834674v1
AB - We present the angular BAO analysis using DESI DR1 data as a complementary approach to DESI's primary 3D BAO analysis. We perform the analysis using the two-point angular correlation function w(θ) in tomographic redshift shells of δz = 0.02, 0.05, spanning the redshift range 0.4 < z < 2.1 using the DESI tracers: LRG1, LRG2, LRG3+ELG1, ELG2 and QSO. The main benefit is that it requires no fiducial cosmology to convert redshifts into distances and yields a direct measurement of the transverse dilation parameter α_⊥(z). We fit each tracer with a single shared α_⊥(z) using templates constructed in a fiducial cosmology and a mock-based covariance from 1000 EZmock realisations. We measure α_⊥ to $2.5$ -- 4.2% precision in each tracer bin. Compared to the D_M/r_d measurements obtained from the DESI DR1 3D analysis for the same tracers, our results are consistent within the statistical precision. We find no evidence for a shift in the transverse BAO scale between the 2D and 3D analyses. Flat ΛCDM fits to α_⊥(z) alone give Ω_m = 0.198^+0.045_−0.068, 1.6σ below the DESI 3D value, and the pull is dominated by the z =1.49 QSO bin, whose α_⊥(z=1.49)=1.058±0.028 sits ∼ 2σ above the fiducial. Restricting to LRGs and ELGs only, our Ω_m and H_0 r_d agree with the 3D transverse-only fit over the same bins to better than 0.1σ. With an additional BBN prior, the full 2D sample gives H_0 = 63.9^+1.9_−3.3 km s^−1 Mpc^−1. This pipeline is implementable on forthcoming DESI data releases, where the increase in volume and sampling density will determine if the QSO offset persists and will also tighten 2D BAO constraints.
ER -