Related papers: Using HI to probe large scale structures at z ~ 3
We simulate the distribution of neutral hydrogen (HI) at the redshifts z=1.3 and 3.4 using a cosmological N-body simulation along with a prescription for assigning HI masses to the particles. The HI is distributed in clouds whose properties…
We investigate the possibility of detecting HI emission from gravitationally lensed HI clouds (akin to damped Lyman-$\alpha$ clouds) at high redshift by carrying out deep radio observations in the fields of known cluster lenses. Such…
The 21 cm emission from neutral hydrogen surveys holds great potential as a valuable method for exploring the large-scale structure of the Universe. In this paper, we forecast for the cross-correlation between the Thermal Sunyaev-Zel'dovich…
Observations of fluctuations in the redshifted 21 cm radiation from neautral hydrogen (HI) are perceived to be an important future probe of the universe at high redshifts. Under the assumption that at redshifts z less than 6…
The emission from neutral hydrogen (HI) clouds in the post-reionization era (z < 6), too faint to be individually detected, is present as a diffuse background in all low frequency radio observations below 1420 MHz. The angular and frequency…
For the GMRT, we calculate the expected signal from redshifted HI emission at two frequency bands centered at 610 and 325 MHz. The study focuses on the visibility-visibility cross-correlations, proposed earlier as the optimal statistical…
We present a statistical method for measuring the average HI spin temperature in distant galaxies using the expected detection yields from future wide-field 21cm absorption surveys. As a demonstrative case study we consider a simulated…
We describe an ongoing experiment to search for the meta-galactic Lyman-continuum background at z~2-3. We are obtaining one of the deepest optical spectra ever, using LRIS/Keck-II to search for the fluorescent Ly-alpha emission from…
We investigate the possibility of probing the large scale structure in the universe at large redshifts by studying fluctuations in the redshifted 1420 MHz emission from the neutral hydrogen (HI) at early epochs. The neutral hydrogen content…
Diffuse Galactic emission at low frequencies is a major contaminant for studies of redshifted $21$ cm line studies. Removal of these foregrounds is essential for exploiting the signal from neutral hydrogen at high redshifts. Analysis of…
Neutral hydrogen (HI) intensity mapping traces the large-scale distribution of matter in the Universe and therefore should correlate with the gamma-ray emission originated from particle dark matter annihilation or from active galactic…
We use a large N-body simulation to examine the detectability of HI in emission at redshift z ~ 1, and the constraints imposed by current observations on the neutral hydrogen mass function of galaxies at this epoch. We consider three…
We present a study of the cosmological Ly$\alpha$ emission signal at $z > 4$. Our goal is to predict the power spectrum of the spatial fluctuations that could be observed by an intensity mapping survey. The model uses the latest data from…
We use a new method to model fluctuations of the Lyman-Werner (LW) and Lyman-alpha radiation backgrounds at high redshift. At these early epochs the backgrounds are symptoms of a universe newly lit with its first stars. LW photons…
The mean and the scatter of the HI content of a dark-matter halo as a function of the halo mass are useful statistics that can be used to test models of structure and galaxy formation. We investigate the possibility of constraining this…
Fast radio bursts (FRBs) emit broad band radio wave radiation that may, in rare cases, encode atomic hydrogen (HI) absorption signals produced as they traverse the interstellar medium of their host galaxies. Combining such signals with high…
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…
Neutral Hydrogen (HI) provides a very important fuel for star formation, but is difficult to detect at high redshift due to weak emission, limited sensitivity of modern instruments, and terrestrial radio frequency interference (RFI) at low…
Line intensity mapping provides a statistical approach to tracing the large-scale distribution of matter in the Universe. We apply the HI intensity mapping technique to interferometric data from the MeerKAT International GHz-Tiered…
Dark gas in the interstellar medium (ISM) is believed to not be detectable either in CO or Hi radio emission, but it is detected by other means including gamma-rays, dust emission and extinction traced outside the Galactic plane at |b|>5…