The Structure and Velocity Field in the Local Supercluster

Introduction

To map structures within 30-40 Mpc, redshift independent distances are needed to remove the effects of peculiar velocities. Methods which provide distances with the lowest errors (5-10% for SBF, TRGB or Cepheids) are often very costly in terms of observing and/or can only be used on the nearest galaxies. Secondary distance indicators such as the luminosity line-width (or Tully-Fisher, TF) relation in spiral galaxies can provide many more measurements out to larger distances, but at the cost of accuracy. To provide the best tracer for local structure and velocity fields, a combination of methods is needed. In this poster we report on a new sample of TF distances which we plane to combine with published primary distances to study the local supercluster (LSC). To further motivate why a good understanding of the local velocity field is desirable, we discuss the effects that the assumption of an incorrect flow model might have on the construction of HI mass functions (HIMFs).

Peculiar Velocity Sample

Why Flow Models Matter - Distances and the HIMF