21cm Cosmology
نویسندگان
چکیده
منابع مشابه
Requirements for Cosmological 21cm Masers
We explore the prospects for a population inversion in the hyperfine levels of atomic hydrogen at high redshifts when the Universe was still predominantly neutral. The existence of 21-cm masers during the epoch of reionisation (EoR) could greatly boost the expected EoR signals. We perform Monte-Carlo calculations of the radiative transfer of Lyα photons emitted by a source embedded in a neutral...
متن کاملTwo New Low Redshift 21cm Absorbers
As part of a larger program to identify low redshift radio analogues of the damped Lyman−α (DLA) absorbers seen in the spectra of high redshift quasars, Westerbork Synthesis Radio Telescope (WSRT) observations have discovered two new HI 21cm absorption lines at z = 0.394 and z = 0.437 in the spectra of the radio sources B 0248+430 and B 1243-072 respectively. These sightlines and redshifts were...
متن کاملThe 21cm Power Spectrum After Reionization
We discuss the 21cm power spectrum (PS) following the completion of reionization. In contrast to the reionization era, this PS is proportional to the PS of mass density fluctuations, with only a small modulation due to fluctuations in the ionization field on scales larger than the mean-free-path of ionizing photons. We derive the form of this modulation, and demonstrate that its effect on the 2...
متن کاملHI 21cm probes of reionization, and beyond
I review the potential for observing cosmic reionization using the HI 21cm line of neutral hydrogren. Studies include observations of the evolution of large scale structure of the IGM (density, excitation temperature, and neutral fraction), through HI 21cm emission, as well as observations of small to intermediate scale structure through absorption toward the first discrete radio sources. I sum...
متن کاملThe 21cm Signature of the First Stars
We predict the 21-cm signature of the first metal-free stars. The soft X-rays emitted by these stars penetrate the atomic medium around their host halos, generating Lyα photons that couple the spin and kinetic temperatures. These creates a region we call the Lyα sphere, visible in 21-cm against the CMB, which is much larger than the HII region produced by the same star. The spin and kinetic tem...
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ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2014
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s174392131401388x