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The radiation background produced by the 21 cm spin-flip transition of neutral hydrogen at high redshifts can be a pristine probe of fundamental physics and cosmology. At z~30-300, the intergalactic medium (IGM) is visible in 21 cm…

Astrophysics · Physics 2008-11-26 Steven Furlanetto , S. Peng Oh , Elena Pierpaoli

Upcoming galaxy surveys with the SKA Observatory will detect neutral hydrogen (HI) across unprecedented volumes, and their scientific return will crucially depend on predictive models for HI observables. In this work, we present a framework…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-25 Joël Mayor , Marta Spinelli , Gabriella De Lucia , Robert Yates , Alexandre Refregier , Fabio Fontanot , Lizhi Xie , Michaela Hirschmann

We model the distribution of the observed profiles of 21 cm line emission from neutral hydrogen (HI) in central galaxies selected from a statistically representative mock catalog of the local Universe in the Lambda-cold dark matter…

Astrophysics of Galaxies · Physics 2021-05-12 Aseem Paranjape , R. Srianand , Tirthankar Roy Choudhury , Ravi K. Sheth

The deep learning technique has been employed in removing foreground contaminants from 21 cm intensity mapping, but its effectiveness is limited by the large dynamic range of the foreground amplitude. In this study, we develop a novel…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-13 Feng Shi , Haoxiang Chang , Le Zhang , Huanyuan Shan , Jiajun Zhang , Suiping Zhou , Ming Jiang , Zitong Wang

Using a novel suite of cosmological simulations zooming in on a Mpc-scale intergalactic sheet or "pancake" at z~3-5, we conduct an in-depth study of the thermal properties and HI content of the warm-hot intergalactic medium (WHIM) at those…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-22 Nir Mandelker , Frank C. van den Bosch , Volker Springel , Freeke van de Voort , Joseph N. Burchett , Iryna S. Butsky , Daisuke Nagai , S. Peng Oh

We have designed, developed, and applied a convolutional neural network (CNN) architecture using multi-task learning to search for and characterize strong HI Lya absorption in quasar spectra. Without any explicit modeling of the quasar…

Astrophysics of Galaxies · Physics 2018-02-14 David Parks , J. Xavier Prochaska , Shawfeng Dong , Zheng Cai

We study the imprint of dark matter (DM) annihilation on the global 21 cm signal from the Dark Ages to Cosmic Reionization. Motivated by recent observations, we focus on three DM candidates: (i) a 10 GeV Bino-like neutralino (ii) a 200 GeV…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-16 Marcos Valdés , Carmelo Evoli , Andrei Mesinger , Andrea Ferrara , Naoki Yoshida

Generative deep learning methods built upon Convolutional Neural Networks (CNNs) provide a great tool for predicting non-linear structure in cosmology. In this work we predict high resolution dark matter halos from large scale, low…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-25 David Schaurecker , Yin Li , Jeremy Tinker , Shirley Ho , Alexandre Refregier

At low radio frequencies (< 100 MHz), classical HII regions may become optically thick (optical depth > 1) and can be observed as discrete absorption regions against the Galactic nonthermal background emission created by Galactic cosmic ray…

Astrophysics · Physics 2008-11-26 Michael E. Nord , P. A. Henning , R. J. Rand , T. Joseph W. Lazio , Namir E. Kassim

A large fraction of baryons predicted from the standard cosmology has been missing observationally. Although previous numerical simulations have indicated that most of the missing baryons reside in large-scale filaments in the form of Warm…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-20 Toshihiro Horii , Shinsuke Asaba , Kenji Hasegawa , Hiroyuki Tashiro

We present the study of CI/H$_2$ relative abundance in the diffuse cold neutral medium. Using the chemical and thermal balance model we calculated the dependence of CI/H$_2$ on the main parameters of the medium: hydrogen number density,…

Astrophysics of Galaxies · Physics 2024-02-02 Sergei Balashev , Daria Kosenko

We present a new map of interstellar reddening, covering the 39\% of the sky with low {\rm HI} column densities ($N_{\rm HI} < 4\times10^{20}\,\rm cm^{-2}$ or $E(B-V)\approx 45\rm\, mmag$) at $16\overset{'}{.}1$ resolution, based on all-sky…

Astrophysics of Galaxies · Physics 2017-09-06 Daniel Lenz , Brandon S. Hensley , Olivier Doré

We present a census of neutral gas in the Milky Way disk and halo down to limiting column densities of $N$(HI)$\sim10^{14}$ cm$^{-2}$ using measurements of HI Lyman-series absorption from the Far Ultraviolet Spectroscopic Explorer (FUSE).…

Interferometric measurements of the 21cm signal are a prime example of the data-driven era in astrophysics we are entering with current and upcoming experiments. We showcase the use of deep networks that are tailored for the structure of 3D…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-30 Caroline Heneka

We present a comparative analysis of interstellar hydrogen (HI) and potassium (KI) absorption from the radio and optical surveys, GASKAP and GALAH, to study the physical and kinematic properties of the cold interstellar medium (ISM) in the…

Intensity mapping of neutral hydrogen (HI) is a promising observational probe of cosmology and large-scale structure. We present wide field simulations of HI intensity maps based on N-body simulations of a $2.6\, {\rm Gpc / h}$ box with…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-02 Sebastian Seehars , Aseem Paranjape , Amadeus Witzemann , Alexandre Refregier , Adam Amara , Joel Akeret

We have carried out an extremely long integration-time (9000 s/beam) 21-cm blind survey of 60 square degrees in Centaurus using the Parkes multibeam system. We find that the noise continues to fall as sqrt(t) throughout, enabling us to…

Deep learning methods have played a more and more important role in hyperspectral image classification. However, the general deep learning methods mainly take advantage of the information of sample itself or the pairwise information between…

Computer Vision and Pattern Recognition · Computer Science 2021-03-30 Zhiqiang Gong , Weidong Hu , Xiaoyong Du , Ping Zhong , Panhe Hu

HI intensity mapping is an emerging tool to probe dark energy. Observations of the redshifted HI signal will be contaminated by instrumental noise, atmospheric and Galactic foregrounds. The latter is expected to be four orders of magnitude…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-28 M. -A. Bigot-Sazy , C. Dickinson , R. A. Battye , I. W. A. Browne , Y. -Z. Ma , B. Maffei , F. Noviello , M. Remazeilles , P. N. Wilkinson

Using a spectral stacking technique, we measure the neutral hydrogen (HI) properties of a sample of galaxies at $z < 0.11$ across 35 pointings of the Westerbork Synthesis Radio Telescope (WSRT). The radio data contains 1,895 galaxies with…

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