Related papers: Warm Neutral Gas at Redshift 3.4

Very sensitive HI 21cm observations have been made in 860 directions at dec >= -43deg in search of weak, Galactic, high-velocity HI emission lines at moderate and high Galactic latitudes. One-third of the observations were made toward…

We study the absorption along lines of sight toward high-z radio sources caused by the 21 cm transition of neutral hydrogen in the intergalactic medium (IGM) before reionization. Using semi-analytic methods, we compute the number density of…

The Westerbork Synthesis Radio Telescope finds a weak 21cm line emission feature at the coordinates (RA-Dec-velocity) of the sub-Damped Lyman-alpha absorber observed at z_abs=0.00632 in the spectrum of PG1216+069. The emission feature,…

The emission in the hyperfine structure 21 cm line of atomic hydrogen arising in the halos with masses $\sim10^6-10^{10}$ M$_\odot$ from the Dark Ages in the models with Warm Dark Matter (WDM) is analysed. The halos are assumed to be formed…

I report detections of four new HI 21-cm absorbers associated with sources at intermediate redshifts, 0.7 < z < 1.0. The sources are part of a sample of 11 radio-loud galaxies, all at 0.7 < z < 1.0, that were searched for associated HI…

Unlike the neutral gas density, which remains largely constant over redshifts of 0 < z < 5, the star formation density exhibits a strong redshift dependence, increasing from the present day before peaking at a redshift of z ~ 2.5. Thus,…

We present results from a search of cold neutral gas associated with radio-loud active galactic nuclei (AGNs) at $z < 0.5$ using HI 21-cm absorption measurements from the MeerKAT Absorption Line Survey (MALS). Cross-matching the MALS 1006…

We report the detection of redshifted HI~21cm absorption in the $z \sim 2.347$ damped Lyman-$\alpha$ absorber (DLA) towards PKS B0438-436, with the Green Bank Telescope. This is the second-highest redshift at which 21cm absorption has been…

We report the detection of HI 21 cm absorption from the $z=2.289$ damped Lyman-$\alpha$ system (DLA) towards TXS 0311+430, with the Green Bank Telescope. The 21 cm absorption has a velocity spread (between nulls) of $\sim 110$ km s$^{-1}$…

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…

Large inhomogeneities in neutral hydrogen in the universe can be detected at redshifts $z \leq 10$ using the redshifted 21 cm line emission. We use cosmological N-Body simulations for dark matter and a simple model for baryonic collapse to…

We report the detection of 21-cm absorption at z = 0.656 towards 1622+238 (3C336). The line is very broad with a Full-Width Half Maximum (FWHM) of 235 km/s, giving a velocity integrated optical depth of 2.2 km/s. The centroid of the line is…

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 report a Giant Metrewave Radio Telescope (GMRT) search for HI 21cm emission from a large sample of star-forming galaxies at $z \approx 1.18 - 1.34$, lying in sub-fields of the DEEP2 Redshift Survey. The search was carried out by…

To search for low-redshift damped Lyman-alpha (DLA) and sub-DLA quasar absorbers, we have conducted a 21cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected from the Sloan Digital Sky Survey…

Neutral hydrogen 21 cm transition is a useful tracer of the neutral interstellar medium. However, inferring physical condition from the observed 21 cm absorption and/or emission spectra is often not straightforward. One complication in…

We have searched for HI 21cm absorption toward the two brightest radio AGN at high redshift, J0924--2201 at $z = 5.20$, and J0913+5919 at $z=5.11$, using the Giant Meter Wave Radio Telescope (GMRT). These data set a 3$\sigma$ upper limit to…

We report on a survey for associated HI 21-cm and OH 18-cm absorption with the Giant Metrewave Radio Telescope at redshifts z = 0.2-0.4. Although the low redshift selection ensures that our targets are below the critical ultra-violet…

We present the results of a search for cold gas at high redshift along QSO lines-of-sight carried out without any a priori assumption on the neutral atomic-hydrogen (HI) content of the absorbers. To do this, we systematically looked for…

We have used the upgraded Giant Metrewave Radio Telescope to carry out a deep (117 on-source hours) L-band observation of the Extended Groth Strip, to measure the average neutral hydrogen (HI) mass and median star formation rate (SFR) of…