A new analytical formalism self-consistently predicts both the ionized fraction x_i(z) and photoionization rate Gamma_HI(z), achieving percent-level accuracy in x_i and 20-30% accuracy in Gamma_HI versus radiative transfer simulations at z less than or equal to 6.
Rapid late-time reionization: constraints and cosmological implications
5 Pith papers cite this work, alongside 2 external citations. Polarity classification is still indexing.
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abstract
We present constraints on the reionization optical depth, $\tau$, obtained using several independent methods. First, we perform a non-parametric reconstruction of the reionization history, using Lyman-$\alpha$ constraints on the evolution of the volume-averaged neutral hydrogen fraction, $x_\mathrm{HI}(z)$, including recent results from the James Webb Space Telescope. When combined with baryon acoustic oscillation (BAO) measurements from DESI and Big Bang nucleosynthesis constraints, these data imply a rapid reionization history ($z_\mathrm{mid}=7.00^{+0.12}_{-0.18}$ and $\Delta z_{50}=1.12^{+0.12}_{-0.29}$) and a value of $\tau=0.0492^{+0.0014}_{-0.0030}$, which is largely insensitive to the assumed cosmological model and independent of cosmic microwave background (CMB) data. The optical depth can also be measured from large-scale $(\ell<30)$ CMB polarization data, yielding constraints that are similarly model-insensitive and consistent with the Ly$\alpha$ bound. Third, $\tau$ may be constrained from the attenuation of small-scale $(\ell>30)$ CMB anisotropies, but the results are sensitive to the choice of cosmological model. Assuming $\Lambda$CDM and combining small-scale CMB data with CMB lensing and type 1a supernovae (SNe) yields tight constraints that are compatible with the Ly$\alpha$ bound. Adding galaxy clustering and lensing measurements brings the constraints further into agreement with the Ly$\alpha$ bound. These independent results reinforce a consensus picture in which reionization is rapid and late. However, the combination of small-scale CMB, CMB lensing, and BAO data yields $\tau=0.094\pm0.011$, which is in $4\sigma$ tension with our Ly$\alpha$ bound. Non-standard reionization scenarios can reconcile some but not all constraints. Concordance is restored in alternative cosmological models, such as models with dynamical dark energy favoured by BAO, CMB, and SNe data.
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A Pop III.1-driven early ionization phase at z=20 yields τ=0.087 consistent with pkSZ and Lyα constraints, potentially resolving BAO-CMB tensions on neutrino mass.
A Gompertzian reionization model with three nuisance parameters demotes optical depth to a derived quantity, reducing its uncertainty by a factor of three and revealing potential neutrino mass tension in CMB analyses.
Cosmological data can constrain only a handful of EFT parameters for single-scalar dark energy; extended models show modest preference over Λ but remain underdetermined and challenged by fifth forces and screening.
The Lumina simulation shows that explicit light-cone integrations produce a CMB optical depth 7% higher than volume-weighted ionization histories, with the excess accumulating near redshift 8 and mass-weighted estimates capturing most of the difference.
citing papers explorer
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A self-consistent analytical model for both the photoionization rate and reionization history
A new analytical formalism self-consistently predicts both the ionized fraction x_i(z) and photoionization rate Gamma_HI(z), achieving percent-level accuracy in x_i and 20-30% accuracy in Gamma_HI versus radiative transfer simulations at z less than or equal to 6.
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Fireworks at Cosmic Dawn: relieving BAO-CMB tensions with the Pop III.1 Flash
A Pop III.1-driven early ionization phase at z=20 yields τ=0.087 consistent with pkSZ and Lyα constraints, potentially resolving BAO-CMB tensions on neutrino mass.
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Into the Gompverse: A robust Gompertzian reionization model for CMB analyses
A Gompertzian reionization model with three nuisance parameters demotes optical depth to a derived quantity, reducing its uncertainty by a factor of three and revealing potential neutrino mass tension in CMB analyses.
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The Status of Single Scalar Field Dark Energy
Cosmological data can constrain only a handful of EFT parameters for single-scalar dark energy; extended models show modest preference over Λ but remain underdetermined and challenged by fifth forces and screening.
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The Lumina Project: CMB Optical Depth Fluctuations from Patchy Reionization
The Lumina simulation shows that explicit light-cone integrations produce a CMB optical depth 7% higher than volume-weighted ionization histories, with the excess accumulating near redshift 8 and mass-weighted estimates capturing most of the difference.