Updated Cosmological Constraints from 2D BAO Measurements: A New Compilation and Comparison with DESI DR2

TL;DR

This work updates the 2D BAO compilation of angular BAO measurements and benchmarks its constraining power against DESI DR2 by combining them with Planck CMB data and modern SN Ia samples. Using a CPL parametrization for dynamical dark energy and a standard ΛCDM baseline, the study finds that 2D BAO data, when integrated with CMB and SNIa, provide constraints that are competitive with DESI-DR2, and show no significant tension with CMB measurements. In ΛCDM, the joint data yield $H_0 \approx 68$ km s$^{-1}$ Mpc$^{-1}$ and $\Sigma m_{\nu} < 0.081$ eV (95% CL), while DESI-DR2 tightens these bounds further; in $w_0w_a$CDM the inclusion of SN Ia hints at dynamical dark energy with $w_0$ around $-0.7$ to $-0.8$ and negative $w_a$, though the degeneracies with $\Sigma m_{\nu}$ keep neutrino mass bounds relatively loose compared to ΛCDM. Overall, the updated 2D BAO compilation proves robust and competitive as a complementary, largely model-independent probe, with future high-redshift $\theta_{\rm BAO}$ measurements from DESI and Euclid expected to sharpen tests of dark energy and neutrino properties without relying on a fiducial cosmology.

Abstract

We investigate and update observational constraints on cosmological parameters within the $Λ$CDM and dynamical dark energy frameworks, using a new compilation of the transverse (or 2D) BAO data, measurements that provide a relatively model-independent estimate of the BAO angular scale at a given redshift. Firstly, we assess the consistency of this compilation with CMB-Planck data and recent BAO results from the DESI collaboration. After confirming minimal tension with CMB data, we perform a series of joint analyses combining CMB data with the 2D~BAO compilation, as well as with several recent Type Ia supernova (SNIa) samples. In all cases, we compare the constraining power of the 2D~BAO data with that of DESI~DR2 samples. Our results indicate that combining 2D~BAO with CMB and SNIa data provides observational constraints that are competitive with those obtained using DESI~DR2. Although the precision of DESI~DR2 results remains higher, as expected due to the more accurate 3D measurements, the 2D~BAO compilation yields strong constraints. For example, in the $Λ$CDM context, we find $H_0 = 68.16^{+0.41}_{-0.37} \,\,\, \text{km s}^{-1}\,\text{Mpc}^{-1}$ (CMB + 2D~BAO) and $Σm_ν < 0.081~\mathrm{eV}$ (95\%~CL). These results are comparable to analogous analyses using DESI~DR2. Several other cases are analyzed and presented in the main text. Due to these results, we conclude that this new 2D~BAO compilation is both robust and competitive in constraining cosmological parameters, and, importantly, it does not exhibit significant tension with CMB measurements.

Figures (5)

• Figure 1: Left panel: Two-dimensional confidence contours at the 68% and 95% confidence levels for the parameters $\Omega_{\mathrm{m}}$ and $H_0$, obtained from different data combinations as indicated in the legend, within the framework of the $\Lambda$CDM model. Right panel: Same as in the left panel, but for several joint analyses combining CMB data with the 2D BAO samples.
• Figure 2: Left panel: Two-dimensional confidence contours at the 68% and 95% confidence levels for the parameters $w_0$ and $w_a$, obtained from different data combinations as indicated in the legend. Right panel: Same as in the left panel, but for several joint analyses combining CMB data with the 2D BAO samples.
• Figure 3: Best-fit models for the rescaled distance–redshift relation, $\theta_{\mathrm{BAO}}(z)$, in the $w_0w_a$CDM (solid line) and $\Lambda$CDM (dashed line) frameworks, derived from the combined analysis of CMB and DESI DR2 data. The black dots correspond to the BAO measurement included in the study, as indicated in the legend. The vertical bars represent the $1\sigma$ observational uncertainties. Bottom panel: Differences between the theoretical predictions and the observed BAO values, expressed in units of their respective observational errors.
• Figure 4: The 68% and 95% confidence regions for the sum of neutrino masses, $\Sigma m_{\nu}$, and the matter density parameter, $\Omega_{\rm m}$, within the $\Lambda$CDM framework. The analysis assumes a prior of $\Sigma m_{\nu} > 0~\mathrm{eV}$. CMB-only constraints reveal a strong positive correlation between $\Sigma m_{\nu}$ and $\Omega_{\rm m}$. Both 2D BAO and DESI BAO data, while largely insensitive to the neutrino mass, provide tight measurements of $\Omega_{\rm m}$, effectively breaking the geometric degeneracy and resulting in a more stringent upper limit on $\Sigma m_{\nu}$.
• Figure 5: Limits on the sum of neutrino masses within the $w_0w_a$CDM framework. The shaded regions represent the 68% and 95% credible intervals of the posterior distribution, assuming a prior of $\Sigma m_{\nu} > 0~\mathrm{eV}$ in all cases.