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Knowledge of the mass composition of ultra-high-energy cosmic rays is crucial to understanding their origins; however, current approaches have limited event-by-event resolution. With fluorescence telescope measurements of the longitudinal…

High Energy Astrophysical Phenomena · Physics 2026-04-10 Zhuoyi Wang , Eric Mayotte , Sonja Mayotte , Nathan Woo , Julia Burton-Heibges , Nicolas San Martin , Cailyn Smith

We study the properties of self-shielding intergalactic absorption systems and their implications for the ionizing background. We find that cosmological simulations post-processed with detailed radiative transfer calculations generally are…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-14 Matthew McQuinn , S. Peng Oh , C. -A. Faucher-Giguere

In this work we present a new hybrid method to simulate the thermal effects of the reionization in cosmological hydrodynamical simulations. The method improves upon the standard approach used in simulations of the intergalactic medium (IGM)…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-11 Jose Oñorbe , F. B. Davies , Z. Lukić , J. F. Hennawi , D. Sorini

We measure the effect of high column density absorbing systems of neutral hydrogen (HI) on the one-dimensional (1D) Lyman-alpha forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-10 Keir K. Rogers , Simeon Bird , Hiranya V. Peiris , Andrew Pontzen , Andreu Font-Ribera , Boris Leistedt

Observations of intergalactic neutral hydrogen can provide a wealth of information about structure and galaxy formation, potentially tracing accretion and feedback processes on Mpc scales. Below a column density of NHI ~ 10^19 cm-2, the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Attila Popping , Romeel Dave , Robert Braun , Benjamin D. Oppenheimer

Computational Fluid Dynamics (CFD) is a hugely important subject with applications in almost every engineering field, however, fluid simulations are extremely computationally and memory demanding. Towards this end, we present Lat-Net, a…

Machine Learning · Statistics 2017-05-26 Oliver Hennigh

We present a post-processing tool for GADGET-2 adiabatic simulations to model various observed properties of the Ly$\alpha$ forest at $2.5 \leq z \leq 4$ that enables an efficient parameter estimation. In particular, we model the thermal…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-06 Prakash Gaikwad , Tirthankar Roy Choudhury , Raghunathan Srianand , Vikram Khaire

We use an automated Voigt-profile fitting procedure to extract statistical properties of the Ly$\alpha$ forest in a numerical simulation of an $\Omega=1$, cold dark matter (CDM) universe. Our analysis method is similar to that used in most…

Astrophysics · Physics 2016-08-30 Romeel Davé , Lars Hernquist , David Weinberg , Neal Katz

Compressing large data sets to a manageable number of summaries that are informative about the underlying parameters vastly simplifies both frequentist and Bayesian inference. When only simulations are available, these summaries are…

Instrumentation and Methods for Astrophysics · Physics 2018-08-06 Tom Charnock , Guilhem Lavaux , Benjamin D. Wandelt

We demonstrate a method for reconstructing the weak lensing potential from the Lyman-$\alpha$ forest data. We derive an optimal estimator for the lensing potential on the sky based on the correlation between pixels in real space. This…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-21 R. Benton Metcalf , Nicolas Tessore , Rupert A. C. Croft

Fuzzy Dark Matter (FDM) represents an alternative and intriguing description of the standard Cold Dark Matter (CDM) fluid, able to explain the lack of direct detection of dark matter particles in the GeV sector and to alleviate small scales…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-30 Matteo Nori , Riccardo Murgia , Vid Iršič , Marco Baldi , Matteo Viel

Ongoing and planned weak lensing (WL) surveys are becoming deep enough to contain information on angular scales down to a few arcmin. To fully extract information from these small scales, we must capture non-Gaussian features in the…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-09 Tianhuan Lu , Zoltán Haiman , José Manuel Zorrilla Matilla

The correlation between Lyman-alpha absorption in the spectra of quasar pairs can be used to measure the transverse distance scale at z~2, which is sensitive to the cosmological constant (Omega_Lambda) or other forms of vacuum energy. Using…

Astrophysics · Physics 2009-11-07 Patrick McDonald

A promising approach to improve climate-model simulations is to replace traditional subgrid parameterizations based on simplified physical models by machine learning algorithms that are data-driven. However, neural networks (NNs) often lead…

Atmospheric and Oceanic Physics · Physics 2021-04-07 Janni Yuval , Paul A. O'Gorman , Chris N. Hill

We investigate the properties of Damped Lyman-alpha systems (DLAs) using high-resolution and large box-size cosmological hydrodynamical simulations of a LambdaCDM model. The numerical code used is a modification of GADGET-2 with a self…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Edoardo Tescari , Matteo Viel , Luca Tornatore , Stefano Borgani

We use the probability distribution function (PDF) of the lya forest flux at z=2-3, measured from high-resolution UVES/VLT data, and hydrodynamical simulations to obtain constraints on cosmological parameters and the thermal state of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 M. Viel , J. S. Bolton , M. G. Haehnelt

It has been recently shown that the astrophysics of reionization can be extracted from the Ly$\alpha$ forest power spectrum by marginalizing the memory of reionization over cosmological information. This impact of cosmic reionization on the…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-07 Paulo Montero-Camacho , Yuchen Liu , Yi Mao

Lyman limit and damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the abundance of such absorbers in…

Astrophysics · Physics 2009-10-28 Jeffrey P. Gardner , Neal Katz , Lars Hernquist , David H. Weinberg

The intergalactic neutral hydrogen which is responsible for the Lyman alpha forest of quasar absorption is a tracer of much larger amounts of ionised hydrogen. The ionised component has yet to be detected directly, but is expected to…

Astrophysics · Physics 2009-11-11 Rupert A. C. Croft , A. J. Banday , Lars Hernquist

We use the Sherwood-Relics suite of hybrid hydrodynamical and radiative transfer simulations to model the effect of inhomogeneous reionisation on the 1D power spectrum of the \Lya forest transmitted flux at redshifts $4.2\leq z \leq 5$.…