THE COSMOLOGICAL DECELERATION PARAMETER ESTIMATED FROM THE ANGULAR-SIZE REDSHIFT RELATION FOR COMPACT RADIO-SOURCES

被引:138
作者
KELLERMANN, KI
机构
[1] National Radio Astronomy Observatory, Charlottesville, VA 22903-2475
关键词
D O I
10.1038/361134a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
IN cosmological models based on the standard Friedmann-Robertson-Walker geometry, the apparent flux density or angular size of standard candles or standard rods varies with redshift in a way that depends on the deceleration parameter q0. (Open universes have q0 < 0.5; closed universes have q0 > 0.5.) At low redshift, however, observational errors are much greater than the differences in q0 expected for different cosmological models, while at high redshift observational uncertainties, particularly at optical wavelengths, and apparent systematic evolutionary changes in sources obscure the expected geometrical effects. Here I show that measurements by very-long-baseline interferometry (VLBI) of compact radio sources associated with active galaxies and quasars may be largely free of evolutionary effects even at substantial redshifts. The relation between angular size and redshift for a sample of these sources indicates a value of q0 close to 0.5, corresponding to cosmological density near the critical value.
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页码:134 / 136
页数:3
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