Angular diameters as a probe of a cosmological constant and Ω

Lawrence Krauss, David N. Schramm

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The lensing effect of curved space, which can cause the angular diameter of a fixed reference length seen on the sky to reach a minimum and then increase with redshift, has recently been claimed to provide evidence, using compact radio sources, for a q0 = 1/2 expansion. We show here that this relation, in particular the position of the observed minimum, depends sensitively on the value of the cosmological constant, Λ, in a flat universe. The sensitivity to a nonzero Λ in a flat universe is compared to the sensitivity to q0 in an open universe without a cosmological constant. The reported results could provide the strongest available limit on the cosmological constant in a flat universe (and on Ω in an open universe) and so we explore how uncertainties in distance measures and evolution of the sources can affect the results. Evolution of less than 30% in source size for z ≤ 2 can completely alter the results, and so must be convincingly ruled out if this technique is to provide a new tool for cosmology.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume405
Issue number2 PART 2
StatePublished - Mar 10 1993
Externally publishedYes

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universe
probe
probes
cosmology
radio
sensitivity
sky
expansion
causes
effect

Keywords

  • Cosmology: theory

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Krauss, L., & Schramm, D. N. (1993). Angular diameters as a probe of a cosmological constant and Ω. Astrophysical Journal, 405(2 PART 2).

Angular diameters as a probe of a cosmological constant and Ω. / Krauss, Lawrence; Schramm, David N.

In: Astrophysical Journal, Vol. 405, No. 2 PART 2, 10.03.1993.

Research output: Contribution to journalArticle

Krauss, L & Schramm, DN 1993, 'Angular diameters as a probe of a cosmological constant and Ω', Astrophysical Journal, vol. 405, no. 2 PART 2.
Krauss, Lawrence ; Schramm, David N. / Angular diameters as a probe of a cosmological constant and Ω. In: Astrophysical Journal. 1993 ; Vol. 405, No. 2 PART 2.
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