VLBI Surveys as a Tool for Cosmological Tests

Abstract

Recent increase in the amount of VLBI data on milliarcsecond structures in AGN stimulated several attempts to revisit the classical idea to use radio sources as cosmological “standard rods” (Hoyle 1959). These attempts have been made by Kellermann (1993a,b), Gurvits (1993, 1994), Pearson et al. (1994), Wilkinson et al. (1997). In several follow up publications, authors critically analyze these attempts pointing out on the necessity to include in the models not only the deceleration parameter q ₀ but also the cosmological constant A (see Krauss and Schramm 1993, Stelmach 1994, Kayser 1995, Jackson and Dodgson 1996). It has been also noted that so far, statistical confidence of the results, in particular estimates of the value q ₀ , is inferior to physical intuition of enthusiasts of the “angular size — redshift” (“θ-z”) test (e.g. Dabrowski et al. 1995, Stepanas and Saha 1995).