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We incorporate quasars into an analytic model to describe the reheating and reionization of the universe. In combination with a previous study of galaxies and Lyman-$\alpha$ clouds, we are able to provide a unified description of structure…

Astrophysics · Physics 2007-05-23 P. Valageas , J. Silk

We present a cosmic density field reconstruction method that augments the traditional reconstruction algorithms with a convolutional neural network (CNN). Following Shallue $\&$ Eisenstein (2022), the key component of our method is to use…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-05 Xinyi Chen , Fangzhou Zhu , Sasha Gaines , Nikhil Padmanabhan

We assess the impact of inhomogeneous reionization on detection of HII regions surrounding luminous high redshift quasars using planned low frequency radio telescopes. Our approach is to implement a semi-numerical scheme to calculate the…

Astrophysics · Physics 2017-07-24 Paul M. Geil , Stuart Wyithe

We present a method to reconstruct the initial linear-regime matter density field from the late-time non-linearly evolved density field in which we channel the output of standard first-order reconstruction to a convolutional neural network…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-23 Christopher J. Shallue , Daniel J. Eisenstein

We present the first large-scale radiative transfer simulations of cosmic reionization, in a simulation volume of (100/h Mpc)^3, while at the same time capturing the dwarf galaxies which are primarily responsible for reionization. We…

A priori, cosmic-ray measurements offer a unique capability to determine the vertical profile of atmospheric temperatures directly from ground. However, despite the increased understanding of the impact of the atmosphere on cosmic-ray…

Atmospheric and Oceanic Physics · Physics 2021-12-10 Riádigos Irma , González-Díaz Diego , Pérez-Muñuzuri Vicente

We consider the deconvolution of the thermal and the turbulent profiles for a pair of ions with different atomic weights under the condition that the lines are formed in an absorbing medium with fluctuating density and velocity fields. Our…

Astrophysics · Physics 2007-05-23 Sergei A. Levshakov , Wilhelm W. Kegel

We investigate the influence of High Mass X-ray Binaries on their high redshift environments. Using a one-dimensional radiative transfer code, we predict the ionization and temperature profiles surrounding a coeval stellar population,…

Astrophysics of Galaxies · Physics 2015-06-22 Gillian Knevitt , Graham Wynn , Chris Power , James Bolton

A novel method, utilizing convolutional neural networks (CNNs), is proposed to reconstruct hyperspectral cubes from computed tomography imaging spectrometer (CTIS) images. Current reconstruction algorithms are usually subject to long…

Image and Video Processing · Electrical Eng. & Systems 2022-03-16 Wei-Chih Huang , Mads Svanborg Peters , Mads Juul Ahlebaek , Mads Toudal Frandsen , René Lynge Eriksen , Bjarke Jørgensen

A new determination of the temperature of the intergalactic medium over $3.9 \leq z \leq 4.3$ is presented. We applied the curvature method on a sample of 10 high resolution quasar spectra from the Ultraviolet and Visual Echelle…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-24 Tomáš Ondro , Rudolf Gális

We train a deep residual convolutional neural network (CNN) to predict the gas-phase metallicity ($Z$) of galaxies derived from spectroscopic information ($Z \equiv 12 + \log(\rm O/H)$) using only three-band $gri$ images from the Sloan…

Astrophysics of Galaxies · Physics 2019-03-04 John F. Wu , Steven Boada

Complex organic molecules (COMs) are observed to be abundant in various astrophysical environments, in particular toward star forming regions they are observed both toward protostellar envelopes as well as shocked regions. Emission spectrum…

Instrumentation and Methods for Astrophysics · Physics 2026-01-14 Nina Kessler , Timea Csengeri , David Cornu , Sylvain Bontemps , Laure Bouscasse

The reionisation time field treion(r) captures the entire history of cosmic reionisation by mapping the moment where each region of the Universe became ionised. Previous work has shown that treion(r) can be inferred from 21-cm observations,…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-12 Julien Hiegel , Dominique Aubert , Émilie Thélie , Rodrigo Ibata , Nicolas Mai

For the temperature field reconstruction (TFR), a complex image-to-image regression problem, the convolutional neural network (CNN) is a powerful surrogate model due to the convolutional layer's good image feature extraction ability.…

Machine Learning · Computer Science 2022-02-15 Xiaohu Zheng , Wen Yao , Zhiqiang Gong , Yunyang Zhang , Xiaoyu Zhao , Tingsong Jiang

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

Tomographic three-dimensional 21 cm images from the epoch of reionization contain a wealth of information about the reionization of the intergalactic medium by astrophysical sources. Conventional power spectrum analysis cannot exploit the…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-22 Xiaosheng Zhao , Yi Mao , Cheng Cheng , Benjamin D. Wandelt

We present a computational imaging mode for large scale electron microscopy data, which retrieves a complex wave from noisy/sparse intensity recordings using a deep learning approach and subsequently reconstructs an image of the specimen…

Materials Science · Physics 2022-02-28 Thomas Friedrich , Chu-Ping Yu , Johan Verbeek , Timothy Pennycook , Sandra Van Aert

Hyperspectral images (HSIs) are susceptible to various noise factors leading to the loss of information, and the noise restricts the subsequent HSIs object detection and classification tasks. In recent years, learning-based methods have…

Neural and Evolutionary Computing · Computer Science 2020-08-18 Yuqiao Liu , Yanan Sun , Bing Xue , Mengjie Zhang

At high redshift, due to both observational limitations and the variety of galaxy morphologies in the early universe, measuring galaxy structure can be challenging. Non-parametric measurements such as the CAS system have thus become an…

Astrophysics of Galaxies · Physics 2021-09-08 C. Tohill , L. Ferreira , C. J. Conselice , S. P. Bamford , F. Ferrari

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