The Gunn—Peterson effect and the Lyman alpha forest
نویسندگان
چکیده
منابع مشابه
The Gunn-Peterson effect and the Lyman alpha forest
We show that spatial correlations in a stochastic large scale velocity field in an otherwise smooth intergalactic medium (homogeneous comoving density) superposed on the general Hubble flow, may cause a ‘line-like’ structure in QSO spectra similar to the population of unsaturated Lyα forest lines which usually are attributed to individual clouds with 10 ∼ NHI ∼ 5× 10 13 cm. Therefore there is n...
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It is shown that many properties of Lyα forest absorbers can be derived using simple physical arguments. Analytical expressions are derived for the density and the size of an absorber as a function of its neutral hydrogen column density, which agree well with both observations and hydrodynamical simulations. An expression is presented to compute ΩIGM from the observed column density distributio...
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We show that it is now possible to image optically thick Ly clouds in uores-cent Ly emission with a relatively long (20 hr) integration on a large (10 m) telescope. For a broad range of column densities (N > 10 18:5 cm 2), the ux of Ly photons from recombination cascades is equal to 0:6 times the ux of ionizing photons, independent of the geometry of the cloud. Additional Ly photons are produce...
متن کاملCosmology with the Lyman-alpha Forest
We outline the physical picture of the high-redshift Lyα forest that has emerged from cosmological simulations, discuss statistical characteristics of the forest that can be used to test theories of structure formation, present a preliminary comparison between simulation predictions and measurements from a sample of 28 Keck HIRES QSO spectra, and summarize the results of a recent determination ...
متن کاملThe Lyman Alpha Forest in Hierarchical Cosmologies
The comparison of quasar absorption spectra with numerically simulated spectra from hierarchical cosmological models of structure formation promises to be a valuable tool to discriminate among these models. We present simulation results for the column density, Doppler b parameter, and optical depth probability distributions for five popular cosmological models.
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1998
ISSN: 0035-8711,1365-2966
DOI: 10.1046/j.1365-8711.1998.01722.x