Related papers: Detecting the relativistic bispectrum in 21cm inte…
The reported detection of the global 21-cm signal by the EDGES collaboration is significantly stronger than standard astrophysical predictions. One possible explanation is an early radio excess above the cosmic microwave background. Such a…
One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral hydrogen. These observations are complicated by the fact that the mapping of redshifts…
We report the first $5\sigma$ detection of HI 21 cm emission from a star-forming galaxy at redshift $z\sim1.3$ (nearly 9 billion years ago) using upgraded Giant Metrewave Radio Telescope (uGMRT). This is the highest redshift HI detection in…
We study the detectability of the cross-correlation between 21 cm emission from the intergalactic medium and the galaxy distribution during (and before) reionization. We show that first-generation 21 cm experiments, such as the Mileura…
The introduction of low-frequency radio arrays is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between a large HII region and the surrounding neutral inter-galactic…
Low redshift surveys of galaxy peculiar velocities provide a wealth of cosmological information. We revisit the idea of extracting this information by directly measuring the redshift-space momentum power spectrum from such surveys. We…
A detection of the 21-cm signal power spectrum from the Epoch of Reionization is imminent, thanks to consistent advancements from telescopes such as LOFAR, MWA, and HERA, along with the development of SKA. In light of this progress, it is…
The star-forming reservoir in the distant Universe can be detected through HI 21-cm absorption arising from either cool gas associated with a radio source or from within a galaxy intervening the sight-line to the continuum source. In order…
Observation of the redshifted 21-cm signal from Cosmic Dawn and Epoch of Reionization is a challenging endeavor in observational cosmology. Presence of orders of magnitude brighter astrophysical foregrounds and various instrumental…
We have undertaken a survey for HI 21-cm absorption within the host galaxies of z ~ 1.2 - 1.5 radio sources, in the search of the cool neutral gas currently "missing" at z > 1. This deficit is believed to be due to the optical selection of…
Detections of the cross correlation signal between the 21cm signal during reionization and high-redshift Lyman Alpha emitters (LAEs) are subject to observational uncertainties which mainly include systematics associated with radio…
Cross-correlations between 21cm observations and galaxy surveys provide a powerful probe of reionization by reducing foreground sensitivity while linking ionization morphology to galaxies. We quantify the constraining power of 21cm-Galaxy…
The potential use of the redshifted 21 cm line from neutral hydrogen for probing the epoch of reionization is motivating the construction of several low-frequency interferometers. There is also much interest in the possibility of…
Relativistic effects are sensitive to subtle changes in dark energy. These effects grow on very large scales and at high redshifts, which will be the reach of upcoming surveys. We investigate these effects in both the linear and the angular…
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…
We generate a set of "relativistic" predictions for the relationship between viewing angle and apparent frequency, for each of three different non-transverse shift equations. We find that a detector aimed transversely (in the lab frame) at…
Next generation surveys will be capable of determining cosmological parameters beyond percent level. To match this precision, theoretical descriptions should look beyond the linear perturbations to approximate the observables in large scale…
The Five-Hundred-Meter Aperture Spherical Radio Telescope(FAST) is the largest single-dish radio telescope in the world. In this paper, we make forecast on the FAST HI large scale structure survey by mock observations. We consider a drift…
We investigate the feasibility of detecting 21cm absorption features in the afterglow spectra of high redshift long Gamma Ray Bursts (GRBs). This is done employing simulations of cosmic reionization, together with the instrumental…
We propose the intensity mapping of the redshifted HI 21-cm signal from the post-reionization epoch as a cosmological probe of $f(R)$ gravity. We consider the Hu-Sawicki class of $f(R)$ gravity models characterized by a single parameter…