Related papers: Cosmology with HI
JWST spectra revealing Lyman-$\alpha$ (Ly$\alpha$) absorption in $z\sim 5-14$ galaxies offer a unique probe of reionization's earliest stages. However, disentangling absorption by the increasingly neutral intergalactic medium (IGM) from…
We review observational tests for the homogeneity of the Universe on large scales. Redshift and peculiar velocity surveys, radio sources, the X-Ray Background, the Lyman-alpha forest and the Cosmic Microwave Background are used to set…
We present the design and methods of the COS-Halos survey, a systematic investigation of the gaseous halos of 44 z = 0.15-0.35 galaxies using background QSOs observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope.…
The survey speed of ASKAP makes it a prime instrument with which to survey the HI universe, enabling it to carry out both wide surveys of the entire sky, as well as deep surveys covering cosmologically representative volumes. Here, the use…
A measurement of the expansion rate of the Universe (that is the Hubble constant, H0) is derived here using the gamma-ray attenuation observed in the spectra of gamma-ray sources produced by the interaction of extragalactic gamma-ray…
The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early…
The reionization of cosmic hydrogen marks a critical juncture in the history of structure formation in the universe. Here we present a new formulation of the standard reionization equation for the evolution of the volume-averaged HII…
We study the constraints which the next generation of radio telescopes could place on the nature of dark energy, dark matter and inflation by studying the gravitational lensing of high redshift 21 cm emission, and we compare with the…
This study presents results on detecting neutral atomic hydrogen (HI) 21cm absorption in the spectrum of PKS1413+135 at redshift $z=0.24670041$. The observation was conducted by FAST, with a spectral resolution of 10 Hz, using 10 minutes of…
Cosmology has come a long way from being based on a small number of observations to being a data-driven precision science. We discuss the questions "What is observable?", "What in the Universe is knowable?" and "What are the fundamental…
The Large Hadron Collider (LHC) provides data which give information on dark matter. In particular, measurements related to the Higgs sector lead to strong constraints on the invisible sector which are competitive with astrophysical limits.…
In order to precisely measure the cosmological parameters and answer the fundamental questions in cosmology, it is necessary to develop new, powerful cosmological probes, in addition to the proposed next-generation optical survey projects.…
The redshifted 1420 MHz emission from the HI in unresolved damped Lyman-\alpha clouds at high z will appear as a background radiation in low frequency radio observations. This holds the possibility of a new tool for studying the universe at…
The cosmic background (CB) radiation, encompassing the sum of emission from all sources outside our own Milky Way galaxy across the entire electromagnetic spectrum, is a fundamental phenomenon in observational cosmology. Many experiments…
Many of the baryons in our Galaxy probably lie outside the well known disk and bulge components. Despite a wealth of evidence for the presence of some gas in galactic halos, including absorption line systems in the spectra of quasars, high…
Neutral hydrogen (HI) is the primary component of the cool interstellar medium (ISM) and is the reservoir of fuel for star formation. Owing to the sensitivity of existing radio telescopes, our understanding of the evolution of the ISM in…
Atomic Hydrogen (HI) is a useful tracer of gas in and around galaxies, and can be found in extended disk-like structures well beyond a system's optical extent. Here we investigate the properties of extended HI disks that emerge in six Milky…
At present neutral atomic hydrogen (HI) gas in galaxies at redshifts above $z \sim 0.3$ (the extent of 21-cm emission surveys in individual galaxies) and below $z \sim 1.7$ (where the Lyman-$\alpha$ line is not observable with ground-based…
The solar system is moving through the partially ionized local interstellar cloud (LIC). The ionized matter of the LIC interacts with the expanding solar wind forming the heliospheric interface. The neutral component (interstellar atoms)…
The universe we observe is homogeneous on super-horizon scales, leading to the ``cosmic homogeneity problem''. Inflation alleviates this problem but cannot solve it within the realm of conservative extrapolations of classical physics. A…