VLBI Studies of High-Redshift 21cm Absorption Lines
نویسندگان
چکیده
منابع مشابه
High Redshift Hi 21cm Absorption toward Red Quasars
We have searched for redshifted absorption in the 21 cm line of neutral hydrogen toward 'red quasars', which are extragalactic radio sources with a steep spectral drop between optical and infrared wavelengths. The success rate for detecting HI 21cm absorption toward a representative sample of such sources is 80%. This compares to the much lower success rate of 11% for detecting HI 21cm absorpti...
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The four known molecular absorption line systems at redshifts z=0.25–0.89 are discussed. Two of the systems originate in the galaxy hosting the ‘background’ AGN, while in two cases the absorption occurs in truely intervening galaxies. Indirect evidence for the existence of very small scale structure in the molecular ISM is presented. A new absorption line at z=0.89 towards PKS1830–211 opens up ...
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The introduction of low-frequency radio arrays is expected to revolutionize the study of the reionization epoch. Observation of the contrast in redshifted 21cm emission between a large HII region and the surrounding neutral inter-galactic medium (IGM) will be the simplest and most easily interpreted signature. However the highest redshift quasars known are thought to reside in an ionized IGM. U...
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The galaxy-IGM part of the Lyman-break survey currently consists of measured redshifts for more than 1000 galaxies with redshift 1.5 < ∼ z < ∼ 3.5 along the sightlines to 25 background QSOs. One of the goals of the survey was to measure the influence on the intergalactic medium of energetic feedback from star and black-hole formation. This talk begins with a description of the observed correlat...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1988
ISSN: 0074-1809
DOI: 10.1017/s0074180900134503