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Before it becomes a sensitive probe of the Epoch of Reionization, the Dark Ages, and fundamental physics, 21 cm tomography must successfully contend with the issue of foreground contamination. Broadband foreground sources are expected to be…

宇宙学与河外天体物理 · 物理学 2012-01-16 Adrian Liu , Max Tegmark

Foreground subtraction in global redshifted 21 cm measurements is limited by frequency-dependent (chromatic) structure in antenna beam patterns. Chromatic beams couple angular structures in Galactic foreground emission to spectral…

天体物理仪器与方法 · 物理学 2015-12-09 Thomas J. Mozdzen , Judd D. Bowman , Raul A. Monsalve , Alan E. E. Rogers

Detecting stochastic gravitational wave background (SGWB) from cosmic strings is crucial for unveiling the evolutionary laws of the early universe and validating non-standard cosmological models. This study presents the first systematic…

宇宙学与河外天体物理 · 物理学 2025-11-18 Geng-Chen Wang , Hong-Bo Jin , Xin Zhang

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…

计算机视觉与模式识别 · 计算机科学 2025-07-04 Hailong Yan , Junjian Huang , Tingwen Huang

Redshifted 21cm signal is a promising tool to investigate the state of intergalactic medium (IGM) in the Cosmic Dawn (CD) and Epoch of Reionization(EoR). In our previous work (Shimabukuro et al 2015), we studied the variance and skewness to…

宇宙学与河外天体物理 · 物理学 2016-04-08 Hayato Shimabukuro , Shintaro Yoshiura , Keitaro Takahashi , Shuichiro Yokoyama , Kiyotomo Ichiki

Mapping the distribution of neutral atomic hydrogen (HI) in the Universe through its 21 cm emission line provides a powerful cosmological probe to map the large-scale structures and shed light on various cosmological phenomena. The Baryon…

宇宙学与河外天体物理 · 物理学 2025-03-20 Albin Joseph , Rajib Saha

The unexpectedly strong 21cm absorption signal detected by the EDGES experiment suggests that the baryonic gas was colder at redshift $z\sim 17$ than predicted in the standard scenario. We discuss a mechanism to lower the baryon temperature…

高能物理 - 唯象学 · 物理学 2018-04-03 Adam Falkowski , Kalliopi Petraki

We present the first application of a new foreground removal pipeline to the current leading HI intensity mapping dataset, obtained by the Green Bank Telescope (GBT). We study the 15hr and 1hr field data of the GBT observations previously…

宇宙学与河外天体物理 · 物理学 2016-10-18 L. Wolz , C. Blake , F. B. Abdalla , C. M. Anderson , T. -C. Chang , Y. -C. Li , K. W. Masui , E. Switzer , U. -L. Pen , T. C. Voytek , J. Yadav

Studies of the cosmic dark ages ($30 \lesssim z \lesssim 150$) using the highly redshifted 21 cm line of neutral hydrogen offer unparalleled amounts of cosmological information, and recent years have seen the refinement of concepts for such…

宇宙学与河外天体物理 · 物理学 2025-08-01 Jonathan C. Pober , Willow Smith

The most promising near-term observable of the cosmic dark age prior to widespread reionization (z~15-200) is the sky-averaged \lambda 21 cm background arising from hydrogen in the intergalactic medium. Though an individual antenna could in…

宇宙学与河外天体物理 · 物理学 2015-06-19 G. Bernardi , M. McQuinn , L. J. Greenhill

The neutral hydrogen 21cm line is potentially a very powerful probe of the observable universe, and a number of on-going experiments are trying to detect it at cosmological distances. However, the presence of strong foreground radiations…

宇宙学与河外天体物理 · 物理学 2019-06-14 Qizhi Huang , Fengquan Wu , Xuelei Chen

Measurements from the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission 2 (ARCADE-2) reveal a strong radio background in the GHz frequency range. Since the cosmological 21-cm signal is measured relative to the background…

宇宙学与河外天体物理 · 物理学 2026-02-17 Sudipta Sikder , Rajesh Mondal , Rennan Barkana , Anastasia Fialkov

A measurement of the cosmological 21 cm signal remains a promising but as-of-yet unattained ambition of radio astronomy. A positive detection would provide direct observations of key unexplored epochs of our cosmic history, including the…

宇宙学与河外天体物理 · 物理学 2015-08-18 Morgan Presley , Adrian Liu , Aaron Parsons

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…

宇宙学与河外天体物理 · 物理学 2026-02-04 Kaifeng Yu , Xin Wang

We explore the properties of interferometric data from high-redshift 21~cm measurements using the Murchison Widefield Array. These data contain redshifted 21~cm signal, contamination from continuum foreground sources, and radiometric noise.…

The cosmic 21 cm signal is set to revolutionise our understanding of the early Universe, allowing us to probe the 3D temperature and ionisation structure of the intergalactic medium (IGM). It will open a window onto the unseen first…

宇宙学与河外天体物理 · 物理学 2018-08-22 Bradley Greig , Andrei Mesinger

Observations of the 21cm Epoch of Reionization (EoR) signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to the development of two main techniques, often referred to as "foreground…

The reliable detection of the global 21-cm signal, a key tracer of Cosmic Dawn and the Epoch of Reionization, requires meticulous data modelling and robust statistical frameworks for model validation and comparison. In Paper I of this…

Seismic data noise processing is an important part of seismic exploration data processing, and the effect of noise elimination is directly related to the follow-up processing of data. In response to this problem, many authors have proposed…

地球物理 · 物理学 2024-10-28 Junheng Peng , Yong Li , Zhangquan Liao , Xuben Wang , Xingyu Yang

Detecting the cosmological sky-averaged (global) 21 cm signal as a function of observed frequency will provide a powerful tool to study the ionization and thermal history of the intergalactic medium (IGM) in the early Universe ($\sim$ 400…

天体物理仪器与方法 · 物理学 2019-09-30 Bang D. Nhan , David D. Bordenave , Richard F. Bradley , Jack O. Burns , Keith Tauscher , David Rapetti , Patricia J. Klima