Direct reconstruction of the Reionization history from 21cm 2D Power Spectra

Abstract

The 21cm line from the spin-flip transition of neutral hydrogen (HI) provides a unique window into the Epoch of Reionization (EoR), the final phase transition of our Universe. The Square Kilometre Array (SKA) enables precise measurements of 21cm fluctuations that trace ionization, temperature, and density fluctuations of the intergalactic medium (IGM). Nevertheless, a direct reconstruction of the timeline of the EoR in terms of the progress of ionization remains an ongoing challenge due to the highly non-Gaussian nature and thus intractable likelihood of the 21cm signal. Here, we present EoRFlow, a simulation-based inference (SBI) framework for reconstructing the global neutral hydrogen fraction $x_{\mathrm{HI}}(z)$ directly from 2D cylindrically averaged power spectra (2DPS) of the 21cm signal. We validate our method on realistic mock datasets for SKA-Low. Bypassing the need for explicit likelihood formulations, our approach enables fast, unbiased posterior estimation of the $x_{\mathrm{HI}}$ evolution in narrow redshift slices, allowing for piecewise reconstruction of the global reionization history. By directly inferring the reionization history from 21cm power spectra, our framework provides a scalable and robust path forward for 21cm cosmology in the SKA era.

21 pages, 10 figures, published in JCAP

References in corpus (23)

• Model-independent evidence in favor of an end to reionization by z~6
• Efficient Simulations of Early Structure Formation and Reionization
• Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\mathbf{z}\approx 9.1$ from LOFAR
• Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample
• The Epoch of Reionization Window: I. Mathematical Formalism
• Real-time gravitational-wave science with neural posterior estimation
• Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations
• First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
• 21cmFAST v3: A Python-integrated C code forgenerating 3D realizations of the cosmic 21cm signal
• Measurements of the z ~ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z > 6.3 Quasar Sample
• The DAWES review 10: The impact of deep learning for the analysis of galaxy surveys
• (Nearly) Model-Independent Constraints on the Neutral Hydrogen Fraction in the Intergalactic Medium at $z\sim 5-7$ Using Dark Pixel Fractions in Ly$\alpha$ and Ly$\beta$ Forests
• Reionization after JWST: a photon budget crisis?
• A new MWA limit on the 21 cm Power Spectrum at Redshifts $\sim$ 13 $-$ 17
• Damping wings in the Lyman-α forest: a model-independent measurement of the neutral fraction at 5.4<z<6.1
• Cosmology with one galaxy?
• Exploring the cosmic 21-cm signal from the Epoch of Reionisation using the Wavelet Scattering Transform
• Modern Machine Learning for LHC Physicists
• Inferring Astrophysics and Dark Matter Properties from 21cm Tomography using Deep Learning
• How informative are summaries of the cosmic 21-cm signal?
• Optimal, fast, and robust inference of reionization-era cosmology with the 21cmPIE-INN
• SKATR: A Self-Supervised Summary Transformer for SKA