Kinematics of the local universe IX. The Perseus-Pisces supercluster and the Tolman-Bondi model

Abstract

We study the mass distribution and the infall pattern of the Perseus-Pisces (PP) supercluster. First we calculate the mass of the central part of PP, a sphere with a radius of 15/h Mpc centered at (l,b)=(140.2°,-22.0°), d=50/h Mpc, using the virial and other estimators. We get M_{PP} = 4 -- 7 /h 10^{15} M_{sun}, giving mass-to-light ratio 200 -- 600 h M_{sun} / L_{sun}, and overdensity δ\approx 4. The radially averaged smoothed density distribution around the PP is inputted to the Tolman-Bondi (TB) equations, calculated for different cosmologies: Ω_0 = [0.1,1], Ω_Λ = 1-Ω_0 or 0. As a result we get the infall velocities towards the PP center. Comparing the TB results to the peculiar velocities measured for the Kinematics of the Local Universe (KLUN) Tully-Fisher data set we get the best fit for the conditions Ω_0 = 0.2 -- 0.4 and v_{inf} < 100 km/s for the Local Group infall towards the center of PP. The applicability of the TB method in a complex environment, such as PP, is tested on an N-body simulation.