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The epoch of reionization is one of the least known chapters in the evolutionary history of the Universe. This thesis investigates two major approaches to unveil the reionization history of the Universe using HI 21-cm maps.The most…

Cosmology and Nongalactic Astrophysics · Physics 2009-06-04 Kanan K. Datta

Intensity mapping experiments survey the spectrum of diffuse line radiation rather than detect individual objects at high signal-to-noise. Spectral maps of unresolved atomic and molecular line radiation contain three-dimensional information…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-19 Eric R. Switzer , Tzu-Ching Chang , Kiyoshi W. Masui , Ue-Li Pen , Tabitha C. Voytek

High-redshift 21-cm observations will provide crucial insights into the physical processes of the Epoch of Reionization. Next-generation interferometers such as the Square Kilometer Array will have enough sensitivity to directly image the…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-27 Simon Gazagnes , Léon V. E. Koopmans , Michael H. F. Wilkinson

Feature Transformation (FT) crafts new features from original ones via mathematical operations to enhance dataset expressiveness for downstream models. However, existing FT methods exhibit critical limitations: discrete search struggles…

Machine Learning · Computer Science 2025-05-22 Nanxu Gong , Zijun Li , Sixun Dong , Haoyue Bai , Wangyang Ying , Xinyuan Wang , Yanjie Fu

Fourier ptychographic microscopy (FPM) is a pivotal computational imaging technique that achieves phase and amplitude reconstruction with high resolution and wide field of view, using low numerical aperture objectives and LED array…

We present a comprehensive analysis of the 21 cm intensity mapping (IM) data from the Tianlai Cylinder Pathfinder Array (TCPA), focusing on multi-scale foreground mitigation and three-dimensional power spectrum estimation. Utilizing 20 days…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-01 Yikai Deng , Shifan Zuo , Jixia Li , Yougang Wang , Xuelei Chen

Subtraction of astrophysical foreground contamination from "dirty" sky maps produced by simulated measurements of the Murchison Widefield Array (MWA) has been performed by fitting a 3rd-order polynomial along the spectral dimension of each…

Astrophysics · Physics 2011-02-11 Judd D. Bowman , Miguel F. Morales , Jacqueline N. Hewitt

Foreground removal remains an ongoing challenge in radio cosmology, and increasingly sensitive experiments necessitate more robust analysis techniques. In this work, we model simulated data from a single-dish intensity mapping experiment,…

Instrumentation and Methods for Astrophysics · Physics 2026-04-30 Geoff G. Murphy , Philip Bull , Mario G. Santos , Zheng Zhang , Steven Cunnington

The 2D power spectrum is a cornerstone of the modern toolkit for analysis of the low-frequency radio interferometric observations of the 21 cm signal arising from the early Universe. Its familiar form disentangles a great deal of systematic…

Instrumentation and Methods for Astrophysics · Physics 2018-12-19 Steven G. Murray , Cathryn M. Trott

This paper provides full sky maps of foreground emission in all WMAP channels, with very low residual contamination from the Cosmic Microwave Background (CMB) anisotropies and controlled level of instrumental noise. Foreground maps are…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-25 Tuhin Ghosh , Jacques Delabrouille , Mathieu Remazeilles , Jean-Francois Cardoso , Tarun Souradeep

With the emergence of wireless applications in three-dimensional environments, such as the low-altitude airspace and 3D heterogeneous networks, radio map estimation is increasingly required to characterize signal propagation across both…

Computer Vision and Pattern Recognition · Computer Science 2026-05-29 Zheng Fang , Junjie Liu , Kangjun Liu , Jianguo Zhang , Yaowei Wang , Ke Chen

A flexible maximum-entropy component separation algorithm is presented that accommodates anisotropic noise, incomplete sky-coverage and uncertainties in the spectral parameters of foregrounds. The capabilities of the method are determined…

Weak gravitational lensing of the 21 cm radiation is expected to be an important cosmological probe for post-reionization physics. We investigate the reconstruction of the matter density perturbations using a quadratic minimum variance…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-10 Priyesh Chakraborty , Anthony R. Pullen

Land surface temperature (LST) super-resolution is important for environmental monitoring. However, it remains challenging as coarse thermal observations severely underdetermine fine-scale structure. In this paper, we propose Earth…

Computer Vision and Pattern Recognition · Computer Science 2026-04-21 Yiheng Chen , Zihui Ma , Peishi Jiang , Yilong Dai , Qikai Hu , Xinyue Ye , Lingyao Li , Rita Sousa , Runlong Yu

An improved method for subtracting contaminants from Cosmic Microwave Background (CMB) sky maps is presented, and used to estimate how well future experiments will be able to recover the primordial CMB fluctuations. We find that the naive…

Astrophysics · Physics 2015-06-24 Max Tegmark , George Efstathiou

It is well-known that foreground subtraction in 21cm surveys removes large scale power. We investigate associated systematic biases. We show that removing line-of-sight fluctuations on large scales aliases into suppression of the 3D power…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Nada Petrovic , S. Peng Oh

We consider the evolution of the sky-averaged 21 cm background during the early phases of structure formation. Using simple analytic models, we calculate the thermal and ionization histories, assuming that stellar photons dominate the…

Astrophysics · Physics 2009-11-11 Steven Furlanetto

Forward modeling the galaxy density within the Effective Field Theory of Large Scale Structure (EFT of LSS) enables field-level analyses that are robust to theoretical uncertainties. At the same time, they can maximize the constraining…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-08 Julia Stadler , Fabian Schmidt , Martin Reinecke , Matteo Esposito

We realize mode-multiplexed full-field reconstruction over six spatial and polarization modes after 30-km multimode fiber transmission using intensity-only measurements without any optical carrier or local oscillator at the receiver or…

Low-light image enhancement is a classical computer vision problem aiming to recover normal-exposure images from low-light images. However, convolutional neural networks commonly used in this field are good at sampling low-frequency local…

Computer Vision and Pattern Recognition · Computer Science 2022-09-19 Yunliang Zhuang , Zhuoran Zheng , Chen Lyu