# Percent-level timing of reionization: self-consistent, implicit-likelihood inference from XQR-30+ Ly$α$ forest data

**Authors:** Yuxiang Qin, Andrei Mesinger, David Prelogović, George Becker, Manuela Bischetti, Sarah E. I. Bosman, Frederick B. Davies, Valentina D'Odorico, Prakash Gaikwad, Martin G. Haehnelt, Laura Keating, Samuel Lai, Emma Ryan-Weber, Sindhu Satyavolu, Fabian Walter, Yongda Zhu  
**arXiv:** [2412.00799](https://arxiv.org/abs/2412.00799)  
**Date:** 2024-12-01  
**Summary page:** https://www.summarizepaper.com/en/paper/2412.00799v1/

## Key points

- Study analyzes Lyman alpha (Lya) forest in high-redshift quasar spectra to investigate late stages of Epoch of Reionization
- Data from extended XQR-30 survey used, Bayesian analysis framework introduced to address discrepancies between models and observed Lya opacity fluctuations
- Refined analysis reveals significant insights into global intergalactic medium (IGM) properties with percent-level precision
- Results suggest reionization concludes at z=5.44±0.02 with EoR mid-point at z=7.7±0.1, ionizing escape fraction increases towards faint galaxies with mild redshift evolution at fixed ultraviolet magnitude (Muv)
- Alternative galaxy models explored offer valuable insights despite being disfavored by Bayesian evidence compared to fiducial model
- Comprehensive analysis provides nuanced understanding of cosmic reionization processes based on detailed observations and sophisticated modeling techniques applied to high-redshift quasar spectra

## Summary

The study focuses on analyzing the Lyman alpha (Lya) forest in high-redshift quasar spectra as a tool to investigate the late stages of the Epoch of Reionization. The authors utilize data from the extended XQR-30 survey and introduce a Bayesian analysis framework to address discrepancies between existing models and observed fluctuations in Lya opacity. Their refined analysis reveals significant insights into global intergalactic medium (IGM) properties with percent-level precision, providing a more accurate representation of cosmic reionization processes. The results suggest that reionization concludes at z=5.44±0.02 with an EoR mid-point at z=7.7±0.1, and that the ionizing escape fraction increases towards faint galaxies with mild redshift evolution at fixed ultraviolet magnitude (Muv). Additionally, alternative galaxy models explored in this study offer valuable insights despite being disfavored by Bayesian evidence compared to the fiducial model. Overall, this comprehensive analysis provides a nuanced understanding of cosmic reionization processes based on detailed observations and sophisticated modeling techniques applied to high-redshift quasar spectra.