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Astron. Astrophys. 357, 393-396 (2000)

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Angular size in "quintessence" cosmology

J.A.S. Lima and J.S. Alcaniz

Departamento de Fisica, UFRN, C.P. 1641, 59072-970 Natal, Brasil

Received 28 October 1999 / Accepted 9 March 2000


We investigate the influence of an exotic fluid component ("quintessence") on the angular size-redshift relation for distant extragalactic sources. Particular emphasis is given for the redshif [FORMULA] at which the angular size takes its minimal value. We derive an analytical closed form which determines how [FORMULA] depends on the parameter of the equation of state describing the exotic component. The results for a flat model dominated by a "quintessence" are compared in detail with the ones for the standard open model dominated by cold dark matter. Some consequences of systematic evolutionary effects on the values of [FORMULA] are also briefly discussed. It is argued that the critical redshift, for all practical purposes, may completely be removed if such effects are taken into account.

Key words: cosmology: theory

Send offprint requests to: limajas@dfte.ufrn.br

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© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000