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Quasar spectra provide a unique opportunity to investigate the intergalactic medium at high redshifts. The spectral analysis of the Ly$\alpha$ forest allows us to constrain the effective equation of state of the intergalactic medium and its…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-02 K N Telikova , S A Balashev , P S Shternin

We describe a novel method for the application of Convolutional Neural Networks (CNNs) to fields defined on the sphere, using the HEALPix tessellation scheme. Specifically, We have developed a pixel-based approach to implement convolutional…

Instrumentation and Methods for Astrophysics · Physics 2019-08-21 Nicoletta Krachmalnicoff , Maurizio Tomasi

We use cosmological simulations of reionization to predict the effect of large HII regions around individual high-redshift quasars on the possible signal from the redshifted 21cm line of neutral hydrogen in the pre-reionization era. We show…

Astrophysics · Physics 2009-11-10 Katharina Kohler , Nickolay Y. Gnedin , Jordi Miralda-Escude , Peter A. Shaver

Particles with masses much larger than the inflationary Hubble scale, $H_I$, can be pair-produced non-adiabatically during inflation. Due to their large masses, the produced particles modify the curvature perturbation around their…

High Energy Physics - Phenomenology · Physics 2023-03-17 Taegyun Kim , Jeong Han Kim , Soubhik Kumar , Adam Martin , Moritz Münchmeyer , Yuhsin Tsai

Recently, convolutional neural networks (CNN) have demonstrated impressive performance in various computer vision tasks. However, high performance hardware is typically indispensable for the application of CNN models due to the high…

Computer Vision and Pattern Recognition · Computer Science 2016-05-17 Jiaxiang Wu , Cong Leng , Yuhang Wang , Qinghao Hu , Jian Cheng

Sophisticated machine learning techniques have promising potential in search for physics beyond Standard Model in Large Hadron Collider (LHC). Convolutional neural networks (CNN) can provide powerful tools for differentiating between…

High Energy Physics - Phenomenology · Physics 2019-12-17 Biplob Bhattacherjee , Swagata Mukherjee , Rhitaja Sengupta

The detection of a HeII absorption trough in the spectra of three high-redshift quasars provides new constraints on the spectral shape of the UV extragalactic background. The relative strengths of the observed flux decrements at the…

Astrophysics · Physics 2007-05-23 Francesco Haardt , Piero Madau

Using information on the cosmic X-ray background and the cumulative light of active galactic nuclei at infrared wavelengths, the estimated local mass density of galactic massive black holes (MBHs) and published AGN composite spectra in the…

Astrophysics · Physics 2016-08-30 S. Yu. Sazonov , J. P. Ostriker , R. A. Sunyaev

Instead of using current deep-learning segmentation models (like the UNet and variants), we approach the segmentation problem using trained Convolutional Neural Network (CNN) classifiers, which automatically extract important features from…

Image and Video Processing · Electrical Eng. & Systems 2022-01-31 Shuyue Guan , Murray Loew

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…

Upcoming 21cm surveys with the SKA1-LOW telescope will enable imaging of the neutral hydrogen distribution on cosmological scales in the early Universe. These surveys are expected to generate huge imaging datasets that will encode more…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-22 Tumelo Mangena , Sultan Hassan , Mario G. Santos

We have constructed a Bayesian neural network able of retrieving tropospheric temperature profiles from rotational Raman-scatter measurements of nitrogen and oxygen and applied it to measurements taken by the RAman Lidar for Meteorological…

Atmospheric and Oceanic Physics · Physics 2023-04-12 Ghazal Farhani , Giovanni Martucci , Tyler Roberts , Alexander Haefele , Robert J. Sica

IceCube DeepCore is an extension of the IceCube Neutrino Observatory designed to measure GeV scale atmospheric neutrino interactions for the purpose of neutrino oscillation studies. Distinguishing muon neutrinos from other flavors and…

High Energy Astrophysical Phenomena · Physics 2026-02-02 J. H. Peterson , M. Prado Rodriguez , K. Hanson

Context. The gas kinetic temperature (TK) determines the physical and chemical evolution of the Interestellar Medium (ISM). However, obtaining reliable TK estimates usually requires expensive observations including the combination of…

Astrophysics of Galaxies · Physics 2020-03-04 A. Hacar , A. D. Bosman , E. F. van Dishoeck

(abridged) Aims. To reconstruct the spectral shape of the quasar ionizing radiation in the extreme-UV range (1Ryd <= E < 10Ryd) from the analysis of narrow absorption lines (NAL) of the associated systems. Methods. Computational technique…

Astrophysics · Physics 2018-10-24 S. A. Levshakov , I. I. Agafonova , D. Reimers , J. L. Hou , P. Molaro

During reionization, neutral hydrogen in the intergalactic medium (IGM) imprints a damping wing absorption feature on the spectrum of high-redshift quasars. A detection of this signature provides compelling evidence for a significantly…

Over the last two decades, around 300 quasars have been discovered at $z\gtrsim6$, yet only one has identified as being strongly gravitationally lensed. We explore a new approach -- enlarging the permitted spectral parameter space, while…

We use a neural network model and ALMA observations of HCN and HNC to constrain the physical conditions, most notably the cosmic-ray ionization rate (CRIR, zeta), in the Central Molecular Zone (CMZ) of the starburst galaxy NGC 253. Using…

We present our results from training and evaluating a convolutional neural network (CNN) to predict galaxy shapes from wide-field survey images of the first data release of the Dark Energy Survey (DES DR1). We use conventional shape…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Dezső Ribli , László Dobos , István Csabai

The reionization of helium is thought to occur at $2.5\lesssim z\lesssim4$, marking the last phase transition and final global heating event of the intergalactic medium (IGM). Since it is driven by rare quasars, helium reionization should…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-13 Saba Etezad-Razavi , Sarah E. I. Bosman , Frederick B. Davies
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