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Redshifted 21 cm radiation originating from the cosmological distribution of neutral hydrogen (HI) appears as a background radiation in low frequency radio observations. The angular and frequency domain fluctuations in this radiation carry…

Astrophysics · Physics 2007-05-23 Somnath Bharadwaj , SK. Saiyad Ali

We interpret observations of intergalactic low ionisation metal absorption systems at redshifts z $\gtrsim$5 in terms of pressure-confined clouds. We find clouds confined by the expected pressure of galactic haloes with masses $11<\log…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-27 Teresita Suarez , Avery Meiksin

The assembly and build-up of neutral atomic hydrogen (HI) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early universe is hindered by the weakness of the…

We have extended our previous analysis of morphologically selected elliptical and S0 galaxies in the Hubble Deep Field (HDF) North to include HST data in the HDF South and the HDFS-NICMOS areas. Our final sample amounts to 69 E/S0 galaxies…

Astrophysics · Physics 2009-11-06 G. Rodighiero , A. Franceschini , G. Fasano

We derive the number density evolution of massive field galaxies in the redshift range 0.4 < z < 1.2 using the K-band selected field galaxy sample from the Munich Near-IR Cluster Survey (MUNICS). We rely on spectroscopically calibrated…

Astrophysics · Physics 2009-11-07 N. Drory , R. Bender , J. Snigula , G. Feulner , U. Hopp , C. Maraston , G. J. Hill , C. Mendes de Oliveira

We outline the case for a comprehensive wide and deep survey ultimately targeted at obtaining 21-cm HI line emission spectroscopic observations of more than a billion galaxies to redshift z=1.5 and greater over half the sky. This survey…

Cosmology and Nongalactic Astrophysics · Physics 2009-03-05 Steven T. Myers , Filipe B. Abdalla , Chris Blake , Leon Koopmans , Joseph Lazio , Steve Rawlings

The high ionization level and universal metallicity (1% solar) of the intergalactic gas at redshifts z<5 implies that nonlinear structure had started to form in the universe at earlier times than we currently probe. In Cold Dark Matter…

Astrophysics · Physics 2009-10-28 Zoltan Haiman , Abraham Loeb

We investigate the metallicity dependence of HI surface densities in star-forming regions along many lines of sight within 70 nearby galaxies, probing kpc to 50 pc scales. We employ HI, SFR, stellar mass, and metallicity (gradient)…

Astrophysics of Galaxies · Physics 2018-08-08 Andreas Schruba , Shmuel Bialy , Amiel Sternberg

The prospect of detecting the first galaxies by observing their impact on the intergalactic medium as they reionized it during the first billion years leads us to ask whether such indirect observations are capable of diagnosing which types…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ilian T. Iliev , Garrelt Mellema , Paul R. Shapiro , Ue-Li Pen , Yi Mao , Jun Koda , Kyungjin Ahn

The neutral hydrogen (HI) power spectrum, measured from intensity fluctuations in the 21-cm background, offers insights into the large-scale structures (LSS) of our Universe in the post-reionization era (redshift $z<6$). A significant…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-10 Mohd Kamran , Martin Sahlén , Debanjan Sarkar , Suman Majumdar

We examine the impact of helium reionization on the structure of the intergalactic medium (IGM). We model the reionization using a radiative transfer (RT) code coupled to the combined gravity hydrodynamics code Enzo. Neutral hydrogen and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 A. Meiksin , E. R. Tittley

We constrain the initial stage of the reionization process around progenitors of galaxies, such as the extent of the initial HII region before its fusion with the UV background and the duration of its propagation. We use a set of…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-05 Jonathan Chardin , Dominique Aubert , Pierre Ocvirk

Cosmic reionization is expected to be complex, extended and very inhomogeneous. Existing constraints at z~6 on the volume-averaged neutral hydrogen fraction, <x_HI>, are highly model-dependent and controversial. Constraints at z<6,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Ian D. McGreer , Andrei Mesinger , Xiaohui Fan

We present cosmological, radiation-hydrodynamics simulations of galaxy formation during the epoch of reionization in an effort towards modelling the interstellar medium (ISM) and interpreting ALMA observations. Simulations with and without…

Astrophysics of Galaxies · Physics 2018-05-02 Harley Katz , Taysun Kimm , Debora Sijacki , Martin Haehnelt

We present resolved HI and CO observations of three galaxies from the HIghMass sample, a sample of HI-massive ($M_{HI} > 10^{10} M_\odot$), gas-rich ($M_{HI}$ in top $5\%$ for their $M_*$) galaxies identified in the ALFALFA survey. Despite…

We present the HI galaxy observation results of the FATHOMER (FAst neuTral HydrOgen intensity Mapping ExpeRiment), a pilot drift scan survey by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The survey comprises 28 hours…

Astrophysics of Galaxies · Physics 2026-03-23 Shuanghao Shu , Yichao Li , Wenxiu Yang , Jiaxin Wang , Wenkai Hu , Furen Deng , Shifan Zuo , Yougang Wang , Xuelei Chen

We use spectral stacking to measure the contribution of galaxies of different masses and in different hierarchies to the cosmic atomic hydrogen (HI) mass density in the local Universe. Our sample includes 1793 galaxies at $z < 0.11$…

We present constraints on the stellar-mass distribution of distant galaxies. These stellar-mass estimates derive from fitting population-synthesis models to the galaxies' observed multi-band spectrophotometry. We discuss the complex…

Astrophysics · Physics 2009-11-07 Casey Papovich , Mark Dickinson , Harry Ferguson

We present the first large-scale radiative transfer simulations of cosmic reionization, in a simulation volume of (100/h Mpc)^3, while at the same time capturing the dwarf galaxies which are primarily responsible for reionization. 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…

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