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At low densities the standard ionisation history of the intergalactic medium (IGM) predicts a decreasing temperature of the IGM with decreasing density once hydrogen (and helium) reionisation is complete. Heating the high-redshift,…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-25 A. Rorai , G. D. Becker , M. G. Haehnelt , R. F. Carswell , J. S. Bolton , S. Cristiani , V. D'Odorico , G. Cupani , P. Barai , F. Calura , T. -S. Kim , E. Pomante , E. Tescari , M. Viel

We use cosmological hydrodynamical simulations to assess the feasibility of constraining the thermal history of the intergalactic medium during reionisation with the Ly$\alpha$ forest at $z\simeq5$. The integrated thermal history has a…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-31 Fahad Nasir , James S. Bolton , George D. Becker

The recent measurement by WMAP of a large electron scattering optical depth tau_e = 0.17 +- 0.04 is consistent with a simple model of reionization in which the intergalactic medium (IGM) is ionized at redshift z ~ 15, and remains highly…

Astrophysics · Physics 2009-11-07 Lam Hui , Zoltan Haiman

We present new measurements of the thermal state of the intergalactic medium (IGM) at $z\sim2.4$ derived from absorption line profiles in the Ly$\alpha$ forest. We use a large set of high-resolution hydrodynamical simulations to calibrate…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 James S. Bolton , George D. Becker , Martin G. Haehnelt , Matteo Viel

It has been realised only recently that TeV emission from blazars can significantly heat the intergalactic medium (IGM) by pair-producing high-energy electrons and positrons, which in turn excite vigorous plasma instabilities, leading to a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ewald Puchwein , Christoph Pfrommer , Volker Springel , Avery E. Broderick , Philip Chang

During the epoch of reionization a large number of photons were produced with frequencies below the hydrogen Lyman limit. After redshifting into the closest resonance, these photons underwent multiple scatterings with atoms. We examine the…

Astrophysics · Physics 2008-11-26 Leonid Chuzhoy , Paul R. Shapiro

The inference of cosmological quantities requires accurate and large hydrodynamical cosmological simulations. Unfortunately, their computational time can take millions of CPU hours for a modest coverage in cosmological scales ($\approx (100…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-03 Chotipan Boonkongkird , Guilhem Lavaux , Sebastien Peirani , Yohan Dubois , Natalia Porqueres , Eleni Tsaprazi

The thermal evolution of the intergalactic medium (IGM) depends on the reionization history of the universe. Numerical simulations indicate that the low density IGM, which is responsible for the low column density Ly-alpha forest, follows a…

Astrophysics · Physics 2007-05-23 Joop Schaye , Tom Theuns , Michael Rauch , George Efstathiou , Wallace L. W. Sargent

High-redshift quasars ionize HeII into HeIII around them, heating the IGM in the process and creating large regions with elevated temperature. In this work, we demonstrate a method based on a convolutional neural network (CNN) to recover…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-18 Huanqing Chen , Rupert Croft , Nickolay Y. Gnedin

The Lyman-$\alpha$ forest offers a unique avenue for studying the distribution of matter in the high redshift universe and extracting precise constraints on the nature of dark matter, neutrino masses, and other $\Lambda$CDM extensions.…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-29 Laura Cabayol-Garcia , Jonás Chaves-Montero , Andreu Font-Ribera , Christian Pedersen

The 21-cm brightness-temperature field of neutral hydrogen during the Epoch of Reionization and Cosmic Dawn is a rich source of cosmological and astrophysical information, primarily due to its significant non-Gaussian features. However, the…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-12 Bohdan Bidenko , Léon V. E. Koopmans , P. Daniel Meerburg

Using high redshift radio sources as background, the 21cm forest observations probe the neutral hydrogen absorption signatures of early structures along the lines of sight. Directly sensitive to the spin temperature, it complements the 21cm…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-18 Yidong Xu , Xuelei Chen , Zuhui Fan , Hy Trac , Renyue Cen

We measure the intergalactic medium (IGM) opacity in the Ly$\alpha$ as well as in the Ly$\beta$ forest along $19$ quasar sightlines between $5.5\lesssim z_{\rm abs}\lesssim 6.1$, probing the end stages of the reionization epoch. Owing to…

Astrophysics of Galaxies · Physics 2019-08-14 Anna-Christina Eilers , Joseph F. Hennawi , Frederick B. Davies , Jose Oñorbe

We re-analyse high redshift and high resolution Lyman-$\alpha$ forest spectra considered in (Viel et al 2013), seeking to constrain the properties of warm dark matter particles. Compared to this previous work, we consider a wider range of…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-18 Antonella Garzilli , Alexey Boyarsky , Oleg Ruchayskiy

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

We compare the improved measurement of the Lya forest flux probability distribution at 1.7<z<3.2 presented by Kim et al. (2007) to a large set of hydrodynamical simulations of the Lya forest with different cosmological parameters and…

Astrophysics · Physics 2009-11-13 J. S. Bolton , M. Viel , T. -S. Kim , M. G. Haehnelt , R. F. Carswell

The inference of astrophysical and cosmological properties from the Lyman-$\alpha$ forest conventionally relies on summary statistics of the transmission field that carry useful but limited information. We present a deep learning framework…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-11 Parth Nayak , Michael Walther , Daniel Gruen , Sreyas Adiraju

We characterise the thermal state of the intergalactic medium (IGM) in ten redshift bins in the redshift range $2 \leq z \leq 4$ with a sample of 103 high resolution, high S/N Ly$\alpha$ forest spectra using four different flux distribution…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-20 Prakash Gaikwad , Raghunathan Srianand , Martin G. Haehnelt , Tirthankar Roy Choudhury

The evolution of the temperature in the intergalactic medium is related to the reionization of hydrogen and helium, and has important consequences for our understanding of the Lya forest and of galaxy formation in gravitational models of…

Central to Earth observation is the trade-off between spatial and temporal resolution. For temperature, this is especially critical because real-world applications require high spatiotemporal resolution data. Current technology allows for…

Image and Video Processing · Electrical Eng. & Systems 2025-07-15 Shengjie Liu , Lu Zhang , Siqin Wang