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We study supernova (SN) classification using the machine learning method of the Recurrent Neural Network (RNN) in the Chinese Space Station Survey Telescope Ultra-Deep Field (CSST-UDF) photometric survey, and explore the improvement of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-05 Minglin Wang , Yan Gong , Dejia Zhou , Xuelei Chen

The observed 21-cm signal from the epoch of reionization will be distorted along the line-of-sight by the peculiar velocities of matter particles. These redshift-space distortions will affect the contrast in the signal and will also make it…

The Square Kilometre Array will be a revolutionary instrument for the study of gas in the distant Universe. SKA1 will have sufficient sensitivity to detect and image atomic 21 cm HI in individual galaxies at significant cosmological…

Astrophysics of Galaxies · Physics 2014-12-19 J. Wagg , E. Da Cunha , C. L. Carilli , F. Walter , M. Aravena , I. Heywood , J. Hodge , E. Murphy , D. Riechers , M. Sargent , R. Wang

Cosmic reionization is known to be a major phase transition of the gas in the Universe. Since astronomical objects formed in the early Universe, such as the first stars, galaxies and black holes, are expected to have caused cosmic…

We discuss the detection of redshifted line and continuum emission at radio wavelengths using a Square Kilometer Array (SKA), specifically from low-excitation rotational molecular line transitions of CO and HCN (molecular lines), the…

Astrophysics · Physics 2009-11-10 Andrew W. Blain , C. L. Carilli , Jeremy Darling

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…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-22 Bradley Greig , Andrei Mesinger

The 21cm forest -- HI absorption features in the spectra of high-redshift radio sources -- can potentially provide a unique probe of the largely neutral intergalactic medium (IGM) during the epoch of reionization. We present simulations of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Katherine J. Mack , J. Stuart B. Wyithe

We explore the impact of reionization topology on 21-cm statistics. Four reionization models are presented which emulate large ionized bubbles around over-dense regions (21CMFAST/ global-inside- out), small ionized bubbles in over-dense…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-15 Catherine A. Watkinson , Jonathan R. Pritchard

We explore the possibility of retrieving cosmological information from 21-cm tomographic data at intermediate redshift. The first step in our approach consists of training an encoder, composed of several three dimensional convolutional…

Instrumentation and Methods for Astrophysics · Physics 2025-07-30 Sambatra Andrianomena

There is growing interest in using 3-dimensional neutral hydrogen mapping with the redshifted 21 cm line as a cosmological probe, as it has been argued to have a greater long-term potential than the cosmic microwave background. However, its…

Astrophysics · Physics 2008-11-26 Yi Mao , Max Tegmark , Matthew McQuinn , Matias Zaldarriaga , Oliver Zahn

Understanding the nature of dark energy is one of the most outstanding problems in cosmology at present. In last twenty years, cosmological observations related to SNIa, Cosmic Microwave Background Radiation, Baryon Acoustic Oscillations…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-01 Bikash R. Dinda , Anjan A Sen , Tirthankar Roy Choudhury

In this paper, we explore the constraints on the reionization history that are provided by current observations of the Lyman-alpha forest and the CMB. Rather than using a particular semi-analytic model, we take the novel approach of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Jonathan R. Pritchard , Abraham Loeb , J. Stuart B. Wyithe

In this paper we investigate how the Square Kilometre Array (SKA) can aid in determining the evolutionary history of active galactic nuclei (AGN) from redshifts z= 0 ->6. Given the vast collecting area of the SKA, it will be sensitive to…

Astrophysics · Physics 2009-11-10 Matt J. Jarvis , Steve Rawlings

The measurement of the large scale distribution of neutral hydrogen in the late Universe, obtained with radio telescopes through the hydrogen 21cm line emission, has the potential to become a key cosmological probe in the upcoming years. We…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-15 Maria Berti , Marta Spinelli , Matteo Viel

The reionization process is driven by ionizing photons from dwarf galaxies in halos with virial temperature $T_{\rm vir} \gtrsim 10^4$ K, while minihalos whose $T_{\rm vir}\lesssim 10^4$ K consume ionizing photons and have negative…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-07 Hourui Zhu , Bin Yue , Yidong Xu , Xuelei Chen , Zhiqi Huang

HI 21~cm absorption spectroscopy provides an excellent probe of the neutral gas content of absorbing galaxies, yielding information on their kinematics, mass, physical size and ISM conditions. The high sensitivity, unrivaled frequency…

Astrophysics · Physics 2009-11-10 N. Kanekar , F. H. Briggs

Detecting and characterizing the Epoch of Reionization and Cosmic Dawn via the redshifted 21-cm hyperfine line of neutral hydrogen will revolutionize the study of the formation of the first stars, galaxies, black holes and intergalactic gas…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-23 F. G. Mertens , A. Ghosh , L. V. E. Koopmans

Cosmic-ray air shower detection with the low-frequency part of the Square Kilometre Array (SKA) radio telescope is envisioned to yield very high precision measurements of the particle composition of cosmic rays between $10^{16}$ and…

High Energy Astrophysical Phenomena · Physics 2025-06-24 A. Corstanje , S. Buitink , S. Bouma , M. Desmet , J. R. Hörandel , T. Huege , P. Laub , K. Mulrey , A. Nelles , O. Scholten , K. Terveer , S. Thoudam , K. Watanabe

HI intensity mapping (IM) is a novel technique capable of mapping the large-scale structure of the Universe in three dimensions and delivering exquisite constraints on cosmology, by using HI as a biased tracer of the dark matter density…

[ABRIDGED] The cosmological 21cm signal is set to become the most powerful probe of the early Universe, with first generation interferometers aiming to make statistical detections of reionization. There is increasing interest also in the…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-08 Andrei Mesinger , Aaron Ewall-Wice , Jacqueline Hewitt