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2001MNRAS.325..631K - Mon. Not. R. Astron. Soc., 325, 631-635 (2001/August-1)
Variable 21-cm absorption at z=0.3127.
KANEKAR N. and CHENGALUR J.N.
Abstract (from CDS):
The observed variations cannot be explained by simple interstellar scintillation (ISS) models where there are only one or two scintillating components and all of the ISS occurs in the Galaxy. More complicated models, where either there are more scintillating components or some of the ISS occurs in the interstellar medium of the z=0.3127 absorber, may be acceptable. However, the variability can probably be best explained in models incorporating motion (on sub-VLBI scales) of a component of the background continuum source, with or without some ISS.
All models producing the variable 21-cm absorption profile require small-scale variations in the 21-cm optical depth of the absorber. The length-scale for the opacity variations is ∼0.1pc in pure superluminal motion models, and ∼10pc in pure ISS models. Models involving subluminal motion, combined with scintillation of the moving component, require opacity variations on far smaller scales of ∼10-100au.
Abstract Copyright: The Royal Astronomical Society
Journal keyword(s): quasars: absorption lines - quasars: individual: PKS 1127-145 - cosmology: observations - radio lines: ISM
Simbad objects: 2
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