# Baryon Acoustic Oscillation Theory and Modelling Systematics for the DESI 2024 results

**Authors:** Shi-Fan Chen, Cullan Howlett, Martin White, Patrick McDonald, Ashley J. Ross, Hee-Jong Seo, Nikhil Padmanabhan, J. Aguilar, S. Ahlen, S. Alam, O. Alves, R. Blum, D. Brooks, X. Chen, S. Cole, T. M. Davis, K. Dawson, A. de la Macorra, Arjun Dey, Z. Ding  
**arXiv:** [2402.14070](https://arxiv.org/abs/2402.14070)  
**Date:** 2024-02-21  
**Summary page:** https://www.summarizepaper.com/en/paper/2402.14070v1/

## Key points

- Comprehensive overview of Baryon Acoustic Oscillation (BAO) fitting process in DESI's 2024 results using DR1 dataset
- Exploration of potential biases in isotropic and anisotropic BAO distance scales due to non-linearities in galaxy clustering
- Mitigation of biases through appropriate choice of reconstruction algorithm
- Introduction of new model for smooth-broadband component of galaxy clustering without BAO signals
- Establishment of best practices for DESI BAO fits through high-precision simulations
- Quantification of theory and modeling systematic error contribution to post-reconstruction DESI BAO measurements (no more than 0.1% for isotropic, 0.2% for anisotropic)
- Robustness of BAO measurements to different modeling choices
- Guidelines applicable beyond DESI era

## Summary

This paper by Shi-Fan Chen et al. provides a comprehensive overview of the Baryon Acoustic Oscillation (BAO) fitting process within the upcoming Dark Energy Spectroscopic Instrument's (DESI) 2024 results using its DR1 dataset. The authors explore potential biases in measurements of the isotropic ($\alpha_{\mathrm{iso}}$) and anisotropic ($\alpha_{\mathrm{ap}}$) BAO distance scales due to non-linearities in galaxy clustering and demonstrate how these can be mitigated with an appropriate choice of reconstruction algorithm. They also introduce a new model for the smooth-broadband component of galaxy clustering without BAO signals and establish best practices for DESI BAO fits through high-precision simulations. Furthermore, they quantify a theory and modeling systematic error contribution to post-reconstruction DESI BAO measurements, estimating it to be no more than $0.1\% ($0.2\%) for isotropic (anisotropic) distance measurements. Overall, this study underscores the robustness of BAO measurements to different modeling choices and sets forth guidelines applicable not only to other BAO experiments in the era of DESI but also beyond.