Dark Energy Survey: DESI-Independent Angular BAO Measurement

TL;DR

This paper measures the angular BAO scale from the Dark Energy Survey data excluding overlap with DESI, and assesses its impact on cosmological model preferences, providing a new independent likelihood and releasing a BAO fitting code.

Contribution

It provides a DESI-independent angular BAO measurement and a publicly available BAO fitting code, refining the statistical significance of dark energy model preferences.

Findings

Smaller increase in the statistical preference for $w_0w_a$CDM with DESI-independent data.

Provides a new independent BAO likelihood for DES BAO data.

Releases the BAO fitting code used in the analysis.

Abstract

We present a measurement of the angular Baryon Acoustic Oscillation (BAO) scale from the completed Dark Energy Survey (DES) dataset excluding the area of overlap with the Dark Energy Spectroscopic Instrument (DESI). We follow the same methodology and validation process as in the DES Y6 BAO analysis. We interpret the impact of this measurement in the context of the statistical preference for $w_0w_a$CDM over $\Lambda$CDM when combined with DES Y5 Type Ia supernovae (SN), Planck Cosmic Microwave Background (CMB) and DESI BAO. Based on our previous work, using the full Y6 DES BAO sample, in combination with SN, CMB and DESI DR1 BAO, added 0.3$\sigma$ in this preference (from 3.7$\sigma$ to 4.0$\sigma$), but this ignored possible correlations between datasets. Using our new DESI-independent DES BAO likelihood instead, we find a smaller increase in the statistical preference for $w_0w_a$CDM, from 3.7$\sigma$ to 3.8$\sigma$ when using DESI DR1 BAO, and from 4.0$\sigma$ to 4.1$\sigma$ when updating to the more recent DESI DR2 BAO. These significances reduce to 3.1$\sigma$ when using the new calibrated DES SN-Dovekie. Alongside this work, we publicly release BAOfit_wtheta, the BAO fitting code for the angular correlation function used in the DES Y6 BAO analysis.