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Hyperspectral image (HSI) densely samples the world in both the space and frequency domain and therefore is more distinctive than RGB images. Usually, HSI needs to be calibrated to minimize the impact of various illumination conditions. The…

Computer Vision and Pattern Recognition · Computer Science 2024-12-23 Zhuoran Du , Shaodi You , Cheng Cheng , Shikui Wei

For many years, there seemed to be significant differences between the continuum intensity distributions derived from observations and simulations of the solar photosphere. In order to settle the discussion on these apparent discrepancies,…

Solar and Stellar Astrophysics · Physics 2009-08-27 S. Wedemeyer-Böhm , L. Rouppe van der Voort

The 21cm emission line from neutral hydrogen (HI) contained within galaxies provides a way to make accurate spectroscopic redshift determinations in the radio part of the spectrum. Large radio arrays such as SKA-MID are coming online that…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-30 Ainulnabilah Nasirudin , Philip Bull , Isabelle Ye

The success of HI intensity mapping is largely dependent on how well 21cm foreground contamination can be controlled. In order to progress our understanding further, we present a range of simulated foreground data from four different…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-25 Steven Cunnington , Melis O. Irfan , Isabella P. Carucci , Alkistis Pourtsidou , Jérôme Bobin

A new type of interferometer, called High Order Harmonic Interferometer (HOHI), was proposed by Wu (1996) for imaging by aperture synthesis radio telescope. Its feasibility was proven by theoretical analysis. Before putting HOHI in…

Instrumentation and Methods for Astrophysics · Physics 2024-03-06 Nailong Wu

We describe algorithms that detect 21cm line HI self-absorption (HISA) in large data sets and extract it for analysis. Our search method identifies HISA as spatially and spectrally confined dark HI features that appear as negative residuals…

Accurately predicting the shape of the HI velocity function of galaxies is regarded widely as a fundamental test of any viable dark matter model. Straightforward analyses of cosmological $N$-body simulations imply that the $\Lambda$CDM…

Astrophysics of Galaxies · Physics 2019-08-14 G. Chauhan , C. D. P. Lagos , D. Obreschkow , C. Power , K. Oman , P. J. Elahi

We use the latest results from Atacama Large Millimetre/submillimetre Array (ALMA) surveys targeting the ionized carbon [CII] 158 $\mu$m and oxygen [OIII] 88 $\mu$m lines, in combination with data-driven predictions for the evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-31 Hamsa Padmanabhan

We present predictions for the 21 cm brightness temperature power spectrum during the Epoch of Reionization (EoR). We discuss the implications of the "light cone" effect, which incorporates evolution of the neutral hydrogen fraction and 21…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-04 Paul La Plante , Nicholas Battaglia , Aravind Natarajan , Jeffrey B. Peterson , Hy Trac , Renyue Cen , Abraham Loeb

Upcoming 21cm surveys will map the spatial distribution of cosmic neutral hydrogen (HI) over unprecedented volumes. Mock catalogues are needed to fully exploit the potential of these surveys. Standard techniques employed to create these…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-02 Digvijay Wadekar , Francisco Villaescusa-Navarro , Shirley Ho , Laurence Perreault-Levasseur

We present here 21 cm predictions from high dynamic range simulations for a range of reionization histories that have been tested against available Lyman-alpha and CMB data. We assess the observability of the predicted spatial 21 cm…

Astrophysics of Galaxies · Physics 2016-09-13 Girish Kulkarni , Tirthankar Roy Choudhury , Ewald Puchwein , Martin G. Haehnelt

The sky-averaged, or global, background of redshifted $21$ cm radiation is expected to be a rich source of information on cosmological reheating and reionizaton. However, measuring the signal is technically challenging: one must extract a…

Instrumentation and Methods for Astrophysics · Physics 2016-08-03 Tejaswi Venumadhav , Tzu-Ching Chang , Olivier Doré , Christopher M. Hirata

This study investigates the estimation of the neutral hydrogen (HI) mass function (HIMF) using a Bayesian stacking approach with simulated data for the Five-hundred-meter Aperture Spherical radio Telescope (FAST) HI intensity mapping (HIIM)…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Jiaxin Wang , Yichao Li , Hengxing Pan , Furen Deng , Diyang Liu , Wenxiu Yang , Wenkai Hu , Yougang Wang , Xin Zhang , Xuelei Chen

Extracting the neutral hydrogen (HI) signal is a great challenge for cosmological 21cm experiments, both the astrophysical foregrounds and the receiver noise are typically several orders of magnitude greater than the 21cm signal. However,…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-14 Qizhi Huang , Fengquan Wu , Reza Ansari , Xuelei Chen

In this review article, we briefly outline our current understanding of the physics associated with the HI 21-cm signal from cosmic dawn. We discuss different phases of cosmic dawn as the ambient gas and the background radiations evolve…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Ankita Bera , Raghunath Ghara , Atrideb Chatterjee , Kanan K. Datta , Saumyadip Samui

We present a forward-modeling framework to forecast the galaxies detected in the Chinese Space Station Survey Telescope (CSST) spectroscopic survey and the Square Kilometre Array (SKA) HI survey. Starting from the L-Galaxies 2020…

Astrophysics of Galaxies · Physics 2026-05-05 Yingfeng Liu , Furen Deng , Wenxiang Pei , Haitao Miao , Qi Xiong , Shuanghao Shu , Xingchen Zhou , Qi Guo , Yan Gong , Yougang Wang , Xuelei Chen

The redshifted 21-cm signal emitted by neutral Hydrogen (HI) is a promising probe to understand the evolution of the topology of ionized regions during the Epoch of Reionization (EoR). The topology of ionized regions allows us to infer the…

Upcoming HI surveys will deliver large datasets, and automated processing using the full 3-D information (two positional dimensions and one spectral dimension) to find and characterize HI objects is imperative. In this context,…

Instrumentation and Methods for Astrophysics · Physics 2015-06-02 D. Punzo , J. M. van der Hulst , J. B. T. M. Roerdink , T. A. Oosterloo , M. Ramatsoku , M. A. W. Verheijen

The distribution of cosmological neutral hydrogen will provide a new window into the large-scale structure of the Universe with the next generation of radio telescopes and surveys. The observation of this material, through 21cm line…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-28 Jacobo Asorey , David Parkinson , Feng Shi , Yong-Seon Song , Kyungjin Ahn , Juhan Kim , Jian Yao , Le Zhang , Shifan Zuo

Three-dimensional radiative transfer simulations of the epoch of reionization can produce realistic results, but are computationally expensive. On the other hand, simulations relying on one-dimensional radiative transfer solutions are…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-21 Raghunath Ghara , Garrelt Mellema , Sambit K. Giri , T. Roy Choudhury , Kanan K. Datta , Suman Majumdar
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