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Lyman-$\alpha$(Ly$\alpha$) forest in the spectra of distant quasars encodes the information of the underlying cosmic density field at smallest scales. The modelling of the upcoming large and high-fidelity forest data using cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-10 Bhaskar Arya

Active Galactic Nuclei (AGN) and star-forming galaxies are leading candidates for being the luminous sources that reionized our Universe. Next-generation 21cm surveys are promising to break degeneracies between a broad range of reionization…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-20 Sultan Hassan , Adrian Liu , Saul Kohn , Paul La Plante

Detecting and characterizing the Epoch of Reionization and Cosmic Dawn via the redshifted 21-cm hyperfine line of neutral hydrogen will revolutionize the study of the formation of the first stars, galaxies, black holes and intergalactic gas…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 F. G. Mertens , A. Ghosh , L. V. E. Koopmans

The one-dimensional flux power spectrum (P1D) of the Lyman-$\alpha$ forest probes small-scale structure in the intergalactic medium (IGM) and is therefore sensitive to a variety of cosmological and astrophysical parameters. These include…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-22 Meagan Herbold , Naim Göksel Karaçaylı , Paul Martini

We estimate the global signal in the redshifted hyperfine structure line 21 cm of hydrogen atoms formed during the Dark Ages and Cosmic Dawn epochs. The evolution of the brightness temperature in this line was computed to study its…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-11 Bohdan Novosyadlyj , Yurii Kulinich , Danylo Koval

We explore the use of Deep Learning to infer physical quantities from the observable transmitted flux in the Lyman-alpha forest. We train a Neural Network using redshift z=3 outputs from cosmological hydrodynamic simulations and mock…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-07 Lawrence Huang , Rupert A. C. Croft , Hitesh Arora

We present methods and results from "21-cm Spectral Line Observations of Neutral Gas with the EVLA" (21-SPONGE), a large survey for Galactic neutral hydrogen (HI) absorption with the Karl G. Jansky Very Large Array (VLA). With the upgraded…

We identify a concordant model for the intergalactic medium (IGM) at redshift z=1.9 that uses popular values for cosmological and astrophysical parameters and accounts for all baryons with an uncertainty of 6%. We have measured the amount…

Our understanding of the intergalactic medium at redshifts $z=5$-$6$ has improved considerably in the last few years due to the discovery of quasars with $z>6$ that enable Lyman-$\alpha$ forest studies at these redshifts. A realisation from…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-08 Janakee Raste , Girish Kulkarni , Laura C. Keating , Martin G. Haehnelt , Jonathan Chardin , Dominique Aubert

Modern machine learning will allow for simulation-based inference from reionization-era 21cm observations at the Square Kilometre Array. Our framework combines a convolutional summary network and a conditional invertible network through a…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-16 Benedikt Schosser , Caroline Heneka , Tilman Plehn

The redshifted 21-cm line from neutral hydrogen ($\textrm{H}\textsc{i}$) enables volumetric intensity mapping of large-scale structure in the post-reionization Universe. In anticipation of \texttt{SKA-MID}'s wide redshift coverage and high…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-28 Sourav Pal , Debanjan Sarkar

We analyze the formation of the redshifted hyperfine structure line 21-cm of hydrogen atom in the Dark Ages, Cosmic Dawn, and Reionization epochs. The evolution of the global differential brightness temperature in this line was computed to…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-27 Bohdan Novosyadlyj , Yurij Kulinich , Gennadi Milinevsky , Valerii Shulga

We present a random forest framework for predicting circumgalactic medium (CGM) physical conditions from quasar absorption line observables, trained on a sample of Voigt profile-fit synthetic absorbers from the Simba cosmological…

Astrophysics of Galaxies · Physics 2023-07-25 Sarah Appleby , Romeel Davé , Daniele Sorini , Christopher Lovell , Kevin Lo

In this paper, we propose a novel method to recover the 21cm global signal from the 21cm power spectrum using artificial neural networks (ANNs). The 21cm global signal is crucial for understanding cosmic evolution from the Dark Ages through…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-09 Hayato Shimabukuro

Next-generation 21cm observations will enable imaging of reionization on very large scales. These images will contain more astrophysical and cosmological information than the power spectrum, and hence providing an alternative way to…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-27 Sultan Hassan , Adrian Liu , Saul Kohn , James E. Aguirre , Paul La Plante , Adam Lidz

The 21 cm signal from the Epoch of Reionization should be observed within the next decade. While a simple statistical detection is expected with SKA pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-28 Hayato Shimabukuro , Benoit Semelin

Future observations of 21 cm emission from neutral hydrogen survey will become a promising approach to probe the large scale structure of Universe. In this paper, we investigate the impacts of Square Kilometer Array (SKA) 21 cm observation…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-12 Jing-Fei Zhang , Li-Yang Gao , Dong-Ze He , Xin Zhang

The Minkowski Functionals (MFs), a set of topological summary statistics, have emerged as a powerful tool for extracting non-Gaussian information. We investigate the prospect of constraining the reionization parameters using the MFs of the…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-10 Kangning Diao , Zhaoting Chen , Xuelei Chen , Yi Mao

We consider the influence of decaying dark matter (DM) particles on the characteristics of 21 cm absorption in spectra of distant radio-loud sources - "21 cm forest" - from minihaloes with masses $M=10^5-10^7\msun$ virialized at $z_{vir} =…

Cosmology and Nongalactic Astrophysics · Physics 2012-05-08 E. O. Vasiliev , Yu. A. Shchekinov

The Lyman-$\alpha$ forest refers to the series of absorption features observed in the spectra of distant quasars that are produced by neutral hydrogen in the intergalactic medium. Observed over a wide range of redshifts with both ground-…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-22 Jonás Chaves-Montero
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