Peculiar velocities at low Galactic latitude

TL;DR

This study assesses the impact of peculiar velocities on the reconstruction of the Laniakea Supercluster within the Zone of Avoidance, using new HI data and infrared photometry to improve understanding of galaxy motions.

Contribution

It provides an analysis of peculiar velocities in the ZOA region, demonstrating that they are manageable for supercluster reconstruction with current data.

Findings

Peculiar velocity corrections are not prohibitively large in the ZOA region.

Additional HI galaxies can be used at Hubble distances for reconstruction.

Reconstruction of Laniakea supercluster is feasible with current data.

Abstract

The Laniakea Supercluster is the closest large scale structure of galaxies. Is such a structure expected in the standard cold dark matter model of cosmology? This would be a relatively simple question to answer, were it not for the fact that the Zone of Avoidance (ZOA) runs right through it. Recent improvements to this paucity of data in the innermost ZOA can be made from systematic 21 cm surveys using the MeerKAT telescope (e.g. Kraan-Korteweg et al. 2024), and implementing these HI-redshifts as an extension to the CosmicFlows4 database for reconstruction (Hollinger et al. 2026). In this paper we test the assumption that for the purpose of reconstruction, additional HI detected galaxies without peculiar velocity determinations could be placed at their Hubble distances. We present infrared photometry of 163 of these in HI detected MeerKAT ZOA galaxies, in addition to 2MASS Extended Sources in the ZOA to determine their peculiar velocities. Averaging these peculiar velocities into redshift bins, we find that peculiar velocity corrections in the Laniakea Supercluster ZoA region are not prohibitively large, and that one can proceed with its reconstruction using the copious redshift data now available.