Development of Hydrogen and Helium Proximity Zones around Quasars
نویسندگان
چکیده
منابع مشابه
Reionization of Hydrogen and Helium by Early Stars and Quasars
We compute the reionization histories of hydrogen and helium due to the ionizing radiation fields produced by stars and quasars. For the quasars we use a model based on halo-merger rates that reproduces all known properties of the quasar luminosity function at high redshifts. The less constrained properties of the ionizing radiation produced by stars are modeled with two free parameters: (i) a ...
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We study the density field around zem > 4 quasars using high quality medium spectral resolution ESI-Keck spectra (R ∼ 4300, SNR > 25) of 45 high-redshift quasars selected from a total of 95 spectra. This large sample considerably increases the statistics compared to previous studies. The redshift evolution of the mean photo-ionization rate and the median optical depth of the intergalactic mediu...
متن کاملHydrogen and Helium
The giant dirigible hovers near the mooring mast and drops its landing lines to the crew on the ground. Suddenly, a sheet of fire bursts from its tail. Within minutes, the 800-ft-long craft is reduced to a tangled mass of charred wreckage; 35 people are dead, and dozens are injured. The accident is famous: the spectacular explosion of the German dirigible, Hindenburg. Less well known, however, ...
متن کاملThe distribution of neutral hydrogen around high-redshift galaxies and quasars in the EAGLE simulation
The observed high covering fractions of neutral hydrogen (H I) with column densities above ∼1017 cm−2 around Lyman-Break Galaxies (LBGs) and bright quasars at redshifts z ∼ 2–3 has been identified as a challenge for simulations of galaxy formation. We use the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulation, which has been shown to reprodu...
متن کاملInfrared Photometry of the Nebulosity around Quasars
Measurements of the nebulosity around quasars have been carried out in the near-infrared. The colors of the host galaxies found in these observations are consistent with those of normal galaxies. The luminosities are also similar to those of normal galaxies but are slightly brighter than average. Subject headings: galaxies: photometry infrared: sources quasars
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2019
ISSN: 1538-4357
DOI: 10.3847/1538-4357/ab3b5c