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Foreground removal is a challenge for 21-cm tomography of the high redshift Universe. We use archival GMRT data (obtained for completely different astronomical goals) to estimate the foregrounds at a redshift ~ 1. The statistic we use is…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-12 Abhik Ghosh , Somnath Bharadwaj , Sk. Saiyad Ali , Jayaram N. Chengalur

The redshifted 21\,cm line is an emerging tool in observational cosmology that can serve as a direct probe of the intergalactic medium throughout the cosmic timeline. However, the observation of the cosmological 21\,cm signal from early…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-12 Samit Kumar Pal , Abhirup Datta , Aishrila Mazumder , Anshuman Tripathi

Observation of multifrequency angular power spectrum of the redshifted 21-cm brightness temperature fluctuation from the neutral hydrogen holds the key to understand the structure formation and its evolution during the reionization and…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-28 Saikat Gayen , Jais Kumar , Prasun Dutta , Khandakar Md Asif Elahi , Samir Choudhuri , Nirupam Roy

One of the main goals of most future CMB experiments is the precise measurement of CMB B-mode polarization, whose major obstacle is the Galactic foregrounds. In this paper, we evaluate the foreground cleaning performance of the variants of…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-24 Jiazheng Dou , Shamik Ghosh , Larissa Santos , Wen Zhao

Relighting a person from a single photo is an attractive but ill-posed task, as a 2D image ambiguously entangles 3D geometry, intrinsic appearance, and illumination. Current methods either use sequential pipelines that suffer from error…

Computer Vision and Pattern Recognition · Computer Science 2026-04-23 Yuxuan Xue , Ruofan Liang , Egor Zakharov , Timur Bagautdinov , Chen Cao , Giljoo Nam , Shunsuke Saito , Gerard Pons-Moll , Javier Romero

The 21-cm intensity mapping (IM) of neutral hydrogen (HI) is a promising tool to probe the large-scale structures. Sky maps of 21-cm intensities can be highly contaminated by different foregrounds, such as Galactic synchrotron radiation,…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-01 Elimboto Yohana , Yin-Zhe Ma , Di Li , Xuelei Chen , Wei-Ming Dai

21cm tomography promises to be a powerful tool for estimating cosmological parameters, constraining the epoch of reionization, and probing the so-called dark ages. However, realizing this promise will require the extraction of a…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-02 Adrian Liu , Max Tegmark

The aim of this work is to propose a joint exploitation of heterogeneous datasets from high-resolution/few-channel experiments and low-resolution/many-channel experiments by using a multiscale needlet Internal Linear Combination (ILC), in…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Mathieu Remazeilles , Nabila Aghanim , Marian Douspis

Foreground contamination is the fundamental hindrance to the cosmic microwave background (CMB) signals and its separation from it represents a fundamental question in Cosmology. One of the most popular algorithm used to disentangle…

Astrophysics · Physics 2008-11-27 R. Vio , P. Andreani

We present in this paper a new Bayesian semi-blind approach for foreground removal in observations of the 21-cm signal with interferometers. The technique, which we call HIEMICA (HI Expectation-Maximization Independent Component Analysis),…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-20 Le Zhang , Emory F. Bunn , Ata Karakci , Andrei Korotkov , P. M. Sutter , Peter T. Timbie , Gregory S. Tucker , Benjamin D. Wandelt

The 21 cm intensity mapping provides a promising probe of the large-scale structure. Astrophysical foregrounds, as the main source of contamination to the cosmological 21 cm signal, persist in a wedge-like region of Fourier space due to the…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-04 Kaifeng Yu , Xin Wang

We present a comprehensive analysis of the performance of noise-reduction (``denoising'') algorithms to determine whether they provide advantages in source detection on extragalactic survey images. The methods under analysis are…

Instrumentation and Methods for Astrophysics · Physics 2020-11-04 V. Roscani , S. Tozza , M. Castellano , E. Merlin , D. Ottaviani , M. Falcone , A. Fontana

Current methods for restoring underexposed images typically rely on supervised learning with paired underexposed and well-illuminated images. However, collecting such datasets is often impractical in real-world scenarios. Moreover, these…

Computer Vision and Pattern Recognition · Computer Science 2025-07-04 Hailong Yan , Junjian Huang , Tingwen Huang

We introduce a new implementation of the FastICA algorithm on simulated LOFAR EoR data with the aim of accurately removing the foregrounds and extracting the 21-cm reionization signal. We find that the method successfully removes the…

We present a novel technique for Cosmic Microwave Background (CMB) foreground subtraction based on the framework of blind source separation. Inspired by previous work incorporating local variation to Generalized Morphological Component…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-28 Sebastian Wagner-Carena , Max Hopkins , Ana Diaz Rivero , Cora Dvorkin

Foreground components in the Cosmic Microwave Background (CMB) are sparse in a needlet representation, due to their specific morphological features (anisotropy, non-Gaussianity). This leads to the possibility of applying needlet…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-01 F. Oppizzi , A. Renzi , M. Liguori , F. K. Hansen , D. Marinucci , C. Baccigalupi , D. Bertacca , D. Poletti

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

Component separation is the process with which emission sources in astrophysical maps are generally extracted by taking multi-frequency information into account. It is crucial to develop more reliable methods for component separation for…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-19 J. M. Casas , L. Bonavera , J. González-Nuevo , C. Baccigalupi , M. M. Cueli , D. Crespo , E. Goitia , J. D. Santos , M. L. Sánchez , F. J. de Cos

This paper introduces a novel deep learning framework for low-light image enhancement, named the Encoder-Decoder Network with Illumination Guidance (EDNIG). Building upon the U-Net architecture, EDNIG integrates an illumination map, derived…

Computer Vision and Pattern Recognition · Computer Science 2025-07-21 Le-Anh Tran , Chung Nguyen Tran , Ngoc-Luu Nguyen , Nhan Cach Dang , Jordi Carrabina , David Castells-Rufas , Minh Son Nguyen

Observations of 21cm line from neutral hydrogen promise to be an exciting new probe of astrophysics and cosmology during the Cosmic Dawn and through the Epoch of Reionization (EoR) to when dark energy accelerates the expansion of the…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-24 Tyler A. Cox , Aaron R. Parsons , Joshua S. Dillon , Aaron Ewall-Wice , Robert Pascua