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We investigate a method to determine the temperature-density relation of the intergalactic medium (IGM) at z~2-4 using quasar absorption line systems. Using a simple model combined with numerical simulations we show that there is a lower…

Astrophysics · Physics 2009-10-31 Greg L. Bryan , Marie E. Machacek

Measurements of the intergalactic medium (IGM) temperature provide a potentially powerful constraint on the reionisation history due to the thermal imprint left by the photo-ionisation of neutral hydrogen. However, until recently IGM…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Sudhir Raskutti , James S. Bolton , J. Stuart B. Wyithe , George D. Becker

At redshifts z >~ 2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyman-alpha forest. This photoheated gas follows a tight temperature-density relation which introduces a…

Astrophysics · Physics 2009-10-31 Joop Schaye , Tom Theuns , Michael Rauch , George Efstathiou , Wallace L. W. Sargent

The amplitude of fluctuations in the Ly-a forest on small spatial scales is sensitive to the temperature of the IGM and its spatial fluctuations. The temperature of the IGM and its spatial variations contain important information about…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Adam Lidz , C. -A. Faucher-Giguere , Aldo Dall'Aglio , Matthew McQuinn , Cora Fechner , Matias Zaldarriaga , Lars Hernquist , Suvendra Dutta

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

We investigate the 21-cm signature that may arise from the intergalactic medium (IGM) prior to the epoch of full reionization (z>5). In scenarios in which the IGM is reionized by discrete sources of photoionizing radiation, the neutral gas…

Astrophysics · Physics 2009-10-28 Piero Madau , Avery Meiksin , Martin J. Rees

We discuss the implementation of Bayesian inversion methods in order to recover the properties of the intergalactic medium from observations of the neutral hydrogen Lyman-$\alpha$ absorptions observed in the spectra of high redshift quasars…

Astrophysics · Physics 2009-11-06 C. Pichon , J. L. Vergely , E. Rollinde , S. Colombi , P. Petitjean

We present a new application of deep learning to reconstruct the cosmic microwave background (CMB) temperature maps from the images of microwave sky, and to use these reconstructed maps to estimate the masses of galaxy clusters. We use a…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-17 N. Gupta , C. L. Reichardt

We present new measurements of the free-streaming of warm dark matter (WDM) from Lyman-$\alpha$ flux-power spectra. We use data from the medium resolution, intermediate redshift XQ-100 sample observed with the X-shooter spectrograph ($z=3 -…

We use measurements of the intergalactic medium (IGM) temperature from the Lyman-$\alpha$ forest to place new limits on models in which long-lived dark sector (DS) particles, with lifetimes longer than $10^{16}$ s, deposit energy into the…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-11 Laura Lopez-Honorez , Sonali Verma

The auto-correlation function of the Lyman-$\alpha$ (Ly$\alpha$) forest flux from high-z quasars can statistically probe all scales of the intergalactic medium (IGM) just after the epoch of reionization. The thermal state of the IGM, which…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-12 Molly Wolfson , Joseph F. Hennawi , Frederick B. Davies , Zarija Lukić , Jose Oñorbe

Full-physics cosmological simulations are powerful tools for studying the formation and evolution of structure in the universe but require extreme computational resources. Here, we train a convolutional neural network to use a cheaper…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-04 Peter Harrington , Mustafa Mustafa , Max Dornfest , Benjamin Horowitz , Zarija Lukić

We have run a new suite of simulations that solve hydrodynamics and radiative transfer simultaneously to study helium II reionization. Our suite of simulations employs various models for populating quasars inside of dark matter halos, which…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-11 Paul La Plante , Hy Trac , Rupert Croft , Renyue Cen

The thermal state of the intergalactic medium (IGM) provides an indirect probe of both the HI and HeII reionisation epochs. Current constraints on the IGM temperature from the Lya forest are restricted to the redshift range 2<z<4.5,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 James S. Bolton , George D. Becker , J. Stuart B. Wyithe , Martin G. Haehnelt , Wallace L. W. Sargent

The post-reionization thermal state of the intergalactic medium is characterized by a power-law relationship between temperature and density, with a slope determined by the parameter $\gamma$. We describe a new method to measure $\gamma$…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-16 Elisa Boera , Michael T. Murphy , George D. Becker , James S. Bolton

Very recently a new inversion method has been developped to analyze the intergalactic medium seen in absorption in quasar spectra (the so-called Lyman-alpha forest). This method is applied to recover the temperature of the gas and the…

We publicly release a new sample of $34$ medium resolution quasar spectra at $5.77\leq z_{\rm em}\leq6.54$ observed with the Echellette Spectrograph and Imager (ESI) on the Keck telescope. This quasar sample represents an ideal laboratory…

Astrophysics of Galaxies · Physics 2018-09-05 Anna-Christina Eilers , Frederick B. Davies , Joseph F. Hennawi

We extend our super-resolution and emulation framework for cosmological dark matter simulations to include hydrodynamics. We present a two-stage deep learning model to emulate high-resolution (HR-HydroSim) baryonic fields from…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-23 Fatemeh Hafezianzadeh , Xiaowen Zhang , Yueying Ni , Rupert A. C. Croft , Tiziana DiMatteo , Mahdi Qezlou , Simeon Bird

A late end to reionisation at redshift $z\simeq 5.3$ is consistent with observed spatial variations in the Ly$\alpha$ forest transmission and the deficit of Ly$\alpha$ emitting galaxies around extended Ly$\alpha$ absorption troughs at…

The thermal state of the intergalactic medium (IGM) at z < 6 constrains the nature and timing of cosmic reionization events, but its inference from the Ly-alpha forest is degenerate with the 3-D structure of the IGM on ~100 kpc scales,…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-14 Girish Kulkarni , Joseph F. Hennawi , Jose Oñorbe , Alberto Rorai , Volker Springel