Galaxy peculiar velocities in the Zone of Avoidance

Abstract

Dust extinction and stellar confusion of the Milky Way hinder the detection of galaxies at low Galactic latitude, creating the so-called Zone of Avoidance (ZoA). This has hampered our understanding of the local dynamics, cosmic flow fields and the origin of the Cosmic Microwave Background dipole. The ZoA ($|b| \le 5^\circ$) is also excluded from the "whole-sky" Two Micron All-Sky Survey (2MASS) Redshift Survey (2MRS) and 2MASS Tully-Fisher Survey (2MTF). The latter aims to provide distances and peculiar velocities for all bright inclined 2MASS galaxies with $K_s^o$ \leq 11\hbox{.\!\!^{\rm m}}25. Correspondingly, knowledge about the density distribution in the ZoA remains limited to statistical interpolations. To improve on this bias we pursued two different surveys to fill in the southern and northern ZoA. These data will allow a direct measurement of galaxy peculiar velocities. In this paper we will present a newly derived optimized Tully-Fisher (TF) relation that allow accurate measures of galaxy distances and peculiar velocities for dust-obscured galaxies. We discuss further corrections for magnitudes and biases and present some preliminary results on flow fields in the southern ZoA.Comment: 6 pages, 3 figures, to appear in Proceedings of SAIP2013, the 58th Annual Conference of the South African Institute of Physics, edited by Roelf Botha and Thulani Jili (SAIP and University of Zululand, 2014). ISBN: 978-0-620-62819-