Introduction



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Introduction

In the last few years deep redshift surveys of the Universe has supplied us with a possibility of mapping the distribution of galaxies with respect to thier spatial location and not only their projected position onto the celestial sphere. By mapping this distribution a large scale structure - if excisting - should be evident.

In different publications it has been inferred that evidence of this kind exists. Geller and Huchra (1989) present results of this kind for the northern hemisphere and recently da Costa et al. (1994) have presented similar results for the southern part of the sky.

A common characteristic for these publications is that they present their distributions mainly in the form of two dimensional plots of slices taken from the entire sample. These slices have been used to identify such famous large scale features as the Great Wall (for the northern survey) and a similar structure (the Southern Wall) in the southern hemisphere, but one could be tempted to ask how structures like these would look if one could see them from the outside, "fly" around them and in other ways examine them in three dimensional space - interactively.

The way towards this goal is of course related to the use of computers and their ability to handle large sets of data and furthermore display these sets in a real time animation. In this way it is possible to get a far better view of the structures and in general of the entire distribution.

The scientific implications of a computerbased visualization in this sense could be of considerable importance. Simulations of the evolution of a CDMgif dominated universe give results that - to a large extent - look like the real universe (White, 1988), but maybe detailed 3D studies could impose further constraints on the models and thus on our understandig of the evolution of the universe as a whole.

A brief overview of the Catalogue

The CfA Redshift Catalogue is a compilation of a large number of sources containing coordinates and radial velocities for galaxies. It incorporates much of the latest velocity data from the Whipple Observatory and other sources as well as velocities from earlier compilations such as the Third Reference Catalogue by de Vaucouleurs, de Vaucouleurs and Corwin, the Index of Galaxy Spectra by Gisler and Friel and the Catalogue of Radial Velocities by Palumbo, Tanzella-Nitti and Vettolani (in this work no indication of source has been made).

The data presented in the catalogue have primarily been assembled for the purpose of studying the large scale structure of the universe and, as such, are nearly complete in redshift (velocity) information. The source data are obtained by means of both wide-angle and pencil-beam surveys and are thus very different in size and coverage.



next up previous contents
Next: Selection and input Up: 3D Redshift Space Visualization Previous: Contents



Bo Milvang-Jensen
Wed Jan 18 05:44:35 MET 1995