Showing papers on "Angular diameter distance published in 1997"
TL;DR: In this article, the authors show that the redshift dependent transition scale is of order a few arc seconds; this implies it should have little influence on large angular scale cosmological tests such as the volume-redshift relation but possibly significant effects on radio galaxies and AGNs.
Abstract: Distance relations in a locally inhomogeneous universe are expected to behave like the Dyer-Roeder solution on small angular scales and the Friedmann-Robertson-Walker solution on large angular scales. Within a simple compact clump model the transition between these asymptotic behaviors is demonstrated and quantified. The redshift dependent transition scale is of order a few arcseconds; this implies it should have little influence on large angular scale cosmological tests such as the volume-redshift relation but possibly significant effects on arcsecond angular diameter measurements of radio galaxies and AGNs. For example, at $z=2$ on arcsecond scales a clumpy flat universe mimics the angular diameter distance of a smooth $\Omega=0.27$ model.
20 citations
TL;DR: In this article, the authors derived effective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-field CCD images and used these to construct the fundamental plane (FP) of the group.
Abstract: We derive new effective radii and total magnitudes for 5 E and S0 galaxies in the Leo-I group from wide-field CCD images. These are used in conjunction with recent literature velocity data to construct the fundamental plane (FP) of the Leo-I group. The rms scatter that we find is only 6 % in distance. The zero point of this relation provides a calibration of the FP as a distance indicator and directly determines the angular diameter distance ratio between the Leo-I group and more distant clusters. In the language of Jerjen and Tammann (1993) we determine a cosmic velocity of the Leo-I group of 757+-68 km/s relative to the Coma cluster, or 796+-57 km/s relative to a frame of 9 clusters. Combining this velocity with the Cepheid distance to M96, a member of Leo-I, we find the Hubble constant to be H_0=67+-8 km/s/Mpc or H_0=70+-7 km/s/Mpc for each case. The distance we obtain for the Coma cluster itself (108+-12 Mpc) is in good agreement with a number of other recent estimates.
10 citations
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TL;DR: In this paper, the usual relation between redshift and angular-diameter distance can be obtained by considering light from a source to be gravitationally lensed by material that lies in the telescope beam as it passes from source to observer through an otherwise empty universe.
Abstract: We show that the usual relation between redshift and angular-diameter distance can be obtained by considering light from a source to be gravitationally lensed by material that lies in the telescope beam as it passes from source to observer through an otherwise empty universe. This derivation yields an equation for the dependence of angular diameter on redshift in an inhomogeneous universe. We use this equation to model the distribution of angular-diameter distance for redshift z=3 in a realistically clustered cosmology. The distribution is such that attempts to determine q_0 from angular-diameter distances will systematically underestimate q_0 by ~0.15, and large samples would be required to beat down the intrinsic dispersion in measured values of q_0.
4 citations
TL;DR: In this paper, a phenomenological study of the putative parameter p such that the redshift varies locally as the pth power of the distance is made, and predictions of cosmology-independent quantities are derived from nonparametric maximum-likelihood estimates of the luminosity function, on the basis of the sample complete in angular diameter of de Vaucouleurs et al.
Abstract: A phenomenological study from first principles is made of the putative parameter p such that the redshift varies locally as the pth power of the distance. The Copernican principle implies that p=1 only with the further assumption that the redshift is a Doppler effect, which is not made here. For each p, predictions of cosmology-independent quantities are derived from nonparametric maximum-likelihood estimates of the luminosity function, on the basis of the sample complete in angular diameter of de Vaucouleurs et al. (1991), consisting of more than 10,000 galaxies. These predictions are then compared with the directly observed values.
3 citations