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Session 86 - Cosmology: Theory.
Display session, Friday, January 09
The bull's-eye effect is a distortion in redshift maps which enhances large scale structures lying transverse to the line of sight. The effect produces maps in which the observer seems to be ringed by concentric walls of galaxies: a bull's-eye.
We investigate the effect in simulations with power-law initial spectra. As in our previous two dimensional study, we find the bull's-eye pattern is strongest for certain values of the power index and that the redshift maps from these simulations give the best qualitative agreement with observation. This suggests that the appearance of observed redshift maps, with their strong walls and filaments, may be misleading. The true distribution of galaxies may have a smoother visual texture, as it does in simulation.
We also find that in three dimensions the bull's-eye pattern has a strong dependence on slice thickness---increasing in strength as the slice is made thicker, in rough agreement with observation. Investigations of simulations and redshift surveys which rely on thin slices may thus miss the effect altogether.
Program listing for Friday