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During reionization, neutral hydrogen in the intergalactic medium (IGM) imprints a damping wing absorption feature on the spectrum of high-redshift quasars. A detection of this signature provides compelling evidence for a significantly…

We investigate the precision with which the Lyman-$\alpha$ damping wing signature imprinted on the spectra of high-redshift quasars (QSOs) by the foreground neutral intergalactic medium (IGM) can measure the history of cosmic reionization.…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-19 Timo Kist , Joseph F. Hennawi , Frederick B. Davies

Lyman-$\alpha$ damping wings towards quasars are a highly sensitive probe of the neutral hydrogen (HI) content in the foreground intergalactic medium (IGM), not only constraining the global timing of reionization but also the \textit{local}…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-01 Timo Kist , Joseph F. Hennawi , Frederick B. Davies

A central challenge in many areas of science and engineering is to identify model parameters that are consistent with prior knowledge and empirical data. Bayesian inference offers a principled framework for this task, but can be…

We introduce a new approach for analyzing the IGM damping wings imprinted on the proximity zones of quasars in the epoch of reionization (EoR). Whereas past work has typically forgone the additional constraining power afforded by the blue…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-17 Joseph F. Hennawi , Timo Kist , Frederick B. Davies , John Tamanas

The standard approach to inference from cosmic large-scale structure data employs summary statistics that are compared to analytic models in a Gaussian likelihood with pre-computed covariance. To overcome the idealising assumptions about…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-24 Kiyam Lin , Maximilian von Wietersheim-Kramsta , Benjamin Joachimi , Stephen Feeney

We quantify and discuss the footprints of neutral hydrogen in the intergalactic medium (IGM) on the spectra of high-redshift (z ~ 6) sources, using mock spectra generated from hydrodynamical simulations of the IGM. We show that it should be…

Astrophysics · Physics 2009-11-10 Andrei Mesinger , Zoltan Haiman , Renyue Cen

Arguably the best hope of understanding the tail end of the reionization of the intergalactic medium (IGM) at redshift z > 6 is through the detection and characterization of the Gunn-Peterson (GP) damping wing absorption of the IGM in…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-25 Roban Hultman Kramer , Zoltan Haiman

Simulation-based inference (SBI) enables parameter inference by training neural networks on forward simulations. It is being applied both for intractable likelihoods as well as under time constraints on the posterior sampling. After…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-12 Leander Thiele

Lyman-$\alpha$ damping wings towards quasars provide a unique probe of reionization because their strength correlates strongly with the global volume-averaged neutral hydrogen (HI) fraction of the intergalactic medium (IGM). Cosmic variance…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-26 Timo Kist , Joseph F. Hennawi , Frederick B. Davies

The incorporation of radiative transfer effects into cosmological hydrodynamical simulations is essential for understanding how the intergalactic medium (IGM) makes the transition from a neutral medium to one that is almost fully ionized.…

Astrophysics · Physics 2009-11-06 Aaron Sokasian , Tom Abel , Lars E. Hernquist

Knowledge of the primordial matter density field from which the large-scale structure of the Universe emerged over cosmic time is of fundamental importance for cosmology. However, reconstructing these cosmological initial conditions from…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-06 Oleg Savchenko , Guillermo Franco Abellán , Florian List , Noemi Anau Montel , Christoph Weniger

Recently, NIRSpec PRISM/CLEAR observations by JWST have begun providing rest-frame UV continuum measurements of galaxies at $z\gtrsim7$, revealing signatures of Ly$\alpha$ damping-wing (DW) absorption by the intergalactic medium (IGM). We…

The 21 cm signal contains a wealth of information about the formation of the first stars and the reionization of the intergalactic medium during the Cosmic Dawn (CD) and Epoch of Reionization (EoR). The timing of these important milestones…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-15 Nadia Cooper , Carina Norregaard , Romain Meriot , Jonathan R. Pritchard

We investigate the possibility of constraining the ionization state of the intergalactic medium (IGM) close to the end of reionization (z ~ 6) by measuring the size of the HII regions in high-z quasars spectra. We perform a combination of…

Astrophysics · Physics 2008-11-26 A. Maselli , S. Gallerani , A. Ferrara , T. R. Choudhury

Simulation-based inference (SBI) is rapidly establishing itself as a standard machine learning technique for analyzing data in cosmological surveys. Despite continual improvements to the quality of density estimation by learned models,…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-03 Pablo Lemos , Miles Cranmer , Muntazir Abidi , ChangHoon Hahn , Michael Eickenberg , Elena Massara , David Yallup , Shirley Ho

We present a Simulation-Based Inference (SBI) framework for cosmological parameter estimation via void lensing analysis. Despite the absence of an analytical model of void lensing, SBI can effectively learn posterior distributions through…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-09 Chen Su , Huanyuan Shan , Cheng Zhao , Wenshuo Xu , Jiajun Zhang

Accurate condition monitoring of industrial equipment requires inferring latent degradation parameters from indirect sensor measurements under uncertainty. While traditional Bayesian methods like Markov Chain Monte Carlo (MCMC) provide…

Machine Learning · Computer Science 2026-04-23 Peter Collett , Alexander Johannes Stasik , Simone Casolo , Signe Riemer-Sørensen

X-ray spectral fitting in high-energy astrophysics can be reliably accelerated using Machine Learning. In particular, Simulation-based Inference (SBI) produces accurate posterior distributions in the Gaussian and Poisson regime for…

Instrumentation and Methods for Astrophysics · Physics 2025-07-09 Simon Dupourqué , Didier Barret

Ionization balance in the intergalactic medium (IGM) is central to the interpretation of quasar absorption spectra, linking observed ionic columns to the underlying gas density, temperature, metallicity, and ionizing radiation field.…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-17 Bhaskar Arya , Kartick C. Sarkar , Shiv K. Sethi
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