منابع مشابه
Λ Decaying as Energy Density: a Study of Angular Size - Redshift Relation
By modifying the Chen & Wu ansatz, we have investigated some Friedmann models in which Λ varies as ρ. In order to test the consistency of the models with observations, we study the angular size redshift relation for 256 ultracompact radio sources selected by Jackson & Dodgson. The angular sizes of these sources were determined by using very long-baseline interferometry in order to avoid any evo...
متن کاملA study of the angular size - redshift relation for models in which Λ decays as the energy density
A study of the angular size-redshift relation for models in which Λ decays as the energy density Abstract. By modifying the Chen and Wu ansatz, we have investigated some Friedmann models in which Λ varies as ρ. In order to test the consistency of the models with observations, we study the angular size-red-shift relation for 256 ultracompact radio sources selected by Jackson and Dodgson. The ang...
متن کاملOptical angular-momentum flux*
We introduce the angular-momentum flux as the natural description of the angular momentum carried by light. We present four main results: (i) angular-momentum flux is the flow of angular momentum across a surface and, in conjunction with the more familiar angular-momentum density, expresses the conservation of angular momentum. (ii) The angular-momentum flux for a light beam about its axis (or ...
متن کاملTight cosmological constraints from the angular-size/redshift relation for ultra-compact radio sources
Some years ago (Jackson and Dodgson 1997) analysis of the angular-size/redshift relationship for ultra-compact radio sources indicted that for spatially flat universes the best choice of cosmological parameters was Ωm = 0.2 and ΩΛ = 0.8. Here I present an astrophysical model of these sources, based upon the idea that for those with redshift z > 0.5 each measured angular size corresponds to a si...
متن کاملRelation between population density and body size in stream communities.
The existence of a general relation between population density and body size in animal assemblages has been debated because of known biases and ambiguities in the published data and data handling. Using new comprehensive data sets from two geographically separated stream communities that encompass 448 and 260 invertebrate taxa with a wide range of body sizes, we show that an inverse proportiona...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1977
ISSN: 0074-1809
DOI: 10.1017/s0074180900016107