Related papers: On the Detectability of the Hydrogen 3-cm Fine Str…
The 21cm line refers to a forbidden transition in neutral hydrogen associated with alignment of spins of the proton and electron. It is a very low energy transition that is emitted whenever there is neutral hydrogen in the Universe. Since…
The extraordinarily bright quasar PHL 1811 at a redshift z = 0.192 provides an attractive opportunity to use ultraviolet absorption-line spectroscopy to study the properties of gas systems in the local universe. An R = 20,000 far-UV…
We explore the possibility of detecting HI 21cm absorption by the neutral intergalactic medium (IGM) toward very high redshift radio sources. The epoch considered is between the time when the first ionizing sources form and when the bulk of…
Using high redshift radio sources as background, the 21cm forest observations probe the neutral hydrogen absorption signatures of early structures along the lines of sight. Directly sensitive to the spin temperature, it complements the 21cm…
The Epoch of Reionization (EoR) began when galaxies grew in abundance and luminosity, so their escaping Lyman continuum (LyC) radiation started ionizing the surrounding neutral intergalactic medium (IGM). Despite significant recent…
We discuss the feasibility of the detection of the 21cm forest in the diffuse IGM with the radio telescope LOFAR. The optical depth to the 21cm line has been derived using simulations of reionization which include detailed radiative…
Measurement of the spatial distribution of neutral hydrogen via the redshifted 21 cm line promises to revolutionize our knowledge of the epoch of reionization and the first galaxies, and may provide a powerful new tool for observational…
We present a first sample of 117 [OIII]$\lambda\lambda$4960,5008-selected star-forming galaxies at $5.33 < z < 6.93$ detected in JWST/NIRCam 3.5$\mu$m slitless spectroscopy of a $6.5 \times 3.4$ arcmin$^2$ field centered on the…
The Lyman alpha absorption from intergalactic, once-ionized helium (HeII) has been measured with HST in four quasars over the last few years, over the redshift range 2.4 < z < 3.2. These observations have indicated that the HeII…
Quasars that allow the study of IGM He II are very rare, since they must be at high redshift along sightlines free of substantial hydrogen absorption, but recent work has dramatically expanded the number of such quasars known. We analyze…
We present new constraints on the 21cm Epoch of Reionization (EoR) power spectrum derived from 3 months of observing with a 32-antenna, dual-polarization deployment of the Donald C. Backer Precision Array for Probing the Epoch of…
We present a study of the transition of Neutral Hydrogen (HI) gas from the end of the Epoch of Reionization (EoR) to late-time large-scale structure. We examine the signature of the transition as traced through the redshifted 21-cm line…
We assess the impact of inhomogeneous reionization on detection of HII regions surrounding luminous high redshift quasars using planned low frequency radio telescopes. Our approach is to implement a semi-numerical scheme to calculate the…
Recent ALMA measurements have revealed bright OIII 88 micron line emission from galaxies during the Epoch of Reionization (EoR) at redshifts as large as $z \sim 9$. We introduce an analytic model to help interpret these and other upcoming…
The Experiment to Detect the Global Epoch of Reionization 21 cm Signal (EDGES) has reported evidence for an absorption feature in the sky-averaged radio background near 78 MHz. A cosmological interpretation of this signal corresponds to…
(Abridged) The existence of an extended neutral hydrogen exosphere around small planets can be used as an evidence for the presence of water in their lower atmosphere but, to date, such feature has not been securely detected in rocky…
We present a sensitive search for the ^3P_1->^3P_0 ground state fine structure line at 205 microns of ionized nitrogen ([NII]) in one of the highest redshift quasars (J1148+5251 at z=6.42) using the IRAM 30m telescope. The line is not…
Detecting $\rm H_I$ 21cm line in the intergalactic medium (IGM) during the Epoch of Reionization (EoR) suffers from foreground contamination such as Galactic synchrotron and extragalactic radio sources. Cross-correlation between the 21cm…
We have studied the small scale distribution of atomic hydrogen (HI) using 21-cm absorption spectra against multiple-component background radio continuum sources from the 21-SPONGE survey and the Millennium Arecibo Absorption Line Survey.…
We study the observability of the reionization epoch through the 21 cm hyperfine transition of neutral hydrogen. We use a high-resolution cosmological simulation (including hydrodynamics) together with a fast radiative transfer algorithm to…