The Bull’s-Eye Effect in 3D Elizabeth Praton Franklin & Marshall College 8/12/2005 Run this in slide show mode.

3-D Numerical Simulation The following slide shows a mock magnitude- limited galaxy survey. Observer is at simulation center, taking slices bounded by constant latitude. Polar plots show longitude vs. distance (real- space) and longitude vs. velocity (redshift- space). Animation shows effect of increasing slice thickness—watch how pattern changes. Simulation Information…

Simulation Information 3-D numerical simulation of gravitational clustering (Melott & Shandarin 1993). Initial power spectrum P(k) ~ k n, n = 0. Periodic boundary conditions. Number of points: (128) 3.

-10° Real Space Redshift Space +10° 5° 22,000 km/s Mag. Limit m < 17 Praton, Melott, & Peterson D Simulation, thick slices

Survey Data The next two slides show results from the CfA redshift survey. Our view in the Zone of Avoidance is blocked by our galaxy’s dusty disk. Slides show result of increasing slice thickness.

45° 20° Dec RA 15,000 km/s 0h 4h 8h 12h 16h 20h Marzke, Huchra, & Geller 1996 Zone of Avoidance CfA Survey mag. limit b < 15.5

45° 20° 0° 20° 0h 4h 8h 12h 16h 20h Marzke, Huchra, & Geller 1996 CfA Survey, thick slices b < 15.5

Conclusions The bull’s-eye pattern gets stronger with increasing slice thickness in both simulation and survey data. This occurs because thicker slices contain more complete filaments than thinner slices.

References Marzke, R.O., Huchra, J.P., & Geller, M.J. 1996, “Large-scale structure at low galactic latitude,” AJ, 112, Melott, A.L. & Shandarin, S.F. 1993, “Controlled experiments in gravitational clustering,” ApJ, 410, 469. Praton, E.A., Melott, A. L., & Peterson, S.A. 1997, “Further investigations of the bull’s-eye effect,” BAAS, 29, 1353.