Towards a Full Census of the Obscure(d) Vela Supercluster using MeerKAT

TL;DR

This paper discusses using MeerKAT radio telescope surveys to map the obscured Vela Supercluster, which is hidden behind the Milky Way, to better understand its structure and impact on cosmic flows.

Contribution

It presents a novel approach using MeerKAT HI surveys to complete the census of the obscured Vela Supercluster, addressing gaps left by optical surveys.

Findings

Simulations show feasible survey time with MeerKAT for the supercluster

Early-science scenarios for MeerKAT observations are outlined

The survey will help estimate the supercluster's mass and influence on cosmic flows

Abstract

Recent spectroscopic observations of a few thousand partially obscured galaxies in the Vela constellation revealed a massive overdensity on supercluster scales straddling the Galactic Equator (l $\sim$ 272.5deg) at $cz \sim 18000$km/s. It remained unrecognised because it is located just beyond the boundaries and volumes of systematic whole-sky redshift and peculiar velocity surveys - and is obscured by the Milky Way. The structure lies close to the apex where residual bulkflows suggest considerable mass excess. The uncovered Vela Supercluster (VSCL) conforms of a confluence of merging walls, but its core remains uncharted. At the thickest foreground dust column densities (|b| < 6 deg) galaxies are not visible and optical spectroscopy is not effective. This precludes a reliable estimate of the mass of VSCL, hence its effect on the cosmic flow field and the peculiar velocity of the Local Group. Only systematic HI-surveys can bridge that gap. We have run simulations and will present early-science observing scenarios with MeerKAT 32 (M32) to complete the census of this dynamically and cosmologically relevant supercluster. M32 has been put forward because this pilot project will also serve as precursor project for HI MeerKAT Large Survey Projects, like Fornax and Laduma. Our calculations have shown that a survey area of the fully obscured part of the supercluster, where the two walls cross and the potential core of the supercluster resides, can be achieved on reasonable time-scales (200 hrs) with M32.