M. O. Hanski

Kinematics of the local universe XII. 21-cm line measurements of 586 galaxies with the new Nançay receiver

This paper presents 586 new 21-cm neutral hydrogen line measurements carried out with the FORT receiver of the meridian transit Nancay radiotelescope in the period July 2000-March 2003. This observational programme is part of a larger project aiming at collecting an exhaustive and magnitude-complete HI extragalactic catalogue for Tully-Fisher applications. It is associated with the building of the MIGALE spectroscopic archive and database.

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

The matter distribution around the Perseus-Pisces (PP) supercluster is studied by comparing peculiar velocities given by the Kinematics of the local universe (KLUN) galaxy sample to those predicted by Tolman-Bondi (TB) models. To restrict the TB solutions we rst solve the mass of the densest part of PP. This part is identied as a sphere at (l;b) = (140:2; 22:0), d 50h 1 Mpc having a radius of 15h 1 Mpc. This sphere surrounds the main part of the PP ridge and four most prominent clusters of the region. Using virial-like mass estimators we calculate the cluster masses and obtain the upper and lower limits for the mass inside the 15h 1 Mpc sphere: MPP = 4{7h 1 10 15 M. This corresponds to a mass overdensity PP 4, or PP =1{2 cr .M ass to light ratios of the clusters are M=L = 200 { 600 hM=L, giving mass density ratio 0 =0 : 1{0 :3, if the value of M=L is assumed to be representative elsewhere in the universe. We estimate a radial density distribution around the PP core using two toy models and a smoothed density distribution observed for IRAS galaxies. The cosmological density parameters (0; ) and the PP mass are free parameters in the TB calculations. The KLUN velocities, obtained by Tully-Fisher relation and the normalized distance method, are adjusted by the Local Group (LG) infall velocity towards PP. Comparison of the TB velocities to KLUN data points indicates that the infall velocity vinf < 100 km s 1 . Allowing MPP to vary within the limits given above we get constraints for the value of 0; 0 =0 :2{0:4 are prefered to the more extreme values, 0 =0 :1 or 1. A choice of either = 1 0 or 0 do not cause any signicant changes in the results. The validity of the TB model in complex environments is studied with an N-body simulation. There we see that the radially averaged velocity elds around simulated clusters are compatible with the corresponding TB velocities. This conrms the applicability of the TB model around large galaxy concentrations, providing that smoothed density and radially averaged velocity elds are used.