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For refcode 1999A&A...342..378G:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
1999A&A...342..378G The "angular size - redshift" relation for compact radio structures in quasars and radio galaxies. GURVITS L.I., KELLERMANN K.I., FREY S. Received 24 June 1998/Accepted 28 September 1998 Abstract: We discuss the "angular size - redshift" relation for compact radio sources distributed over a wide range of redshifts 0.011<=z<=4.72. Our study is based on a sample of 330 5 GHz VLBI contour maps taken from the literature. Unlike extended source samples, the "angular size - redshift" relation for compact radio sources appears consistent with the predictions of standard Friedmann world models with q_0_=~0.5 without the need to consider evolutionary or selection effects due to a "linear size - luminosity" dependence. By confining our analysis to sources having a spectral index, -0.38<={alpha}<=0.18, and a total radio luminosity, Lh^2^>=10^26^W/Hz (H_0_=100hkm/s/Mpc, q_0_=0.5 used as a numerical example), we are able to restrict the dispersion in the "angular size - redshift" relation. The best fitting regression analysis in the framework of the Friedmann-Robertson-Walker model gives the value of the deceleration parameter q_0_ = 0.21+/-0.30 if there are no evolutionary or selection effects due to a "linear size - luminosity", "linear size - redshift" or "linear size - spectral index" dependence. Keywords: galaxies: active - galaxies: quasars: general - cosmology: observations - radio continuum: galaxies
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