RSAA Colloquia / Seminars / Feast-of-Facts: Tuesday, 29 May 2018, 11:00-12:00; Duffield Lecture Theatre

Renee Kraan-Korteweg

"The Vela Supercluster: Discovery and Implications"

Recent spectroscopic observations of a few thousand galaxies revealed an extended galaxy overdensity on supercluster scales close to the Zone of Avoidance in Vela. Due to dust obscuration it had not been recognised as such. Moreover, at a redshift distance of ~18000km/s it is located just beyond the boundaries and volumes of systematic whole-sky redshift and peculiar velocity survey. Interestingly, the structure lies conspicuously close to the apex where residual bulk-flows suggest considerable mass excess. This discovery demonstrates that we still do not know our cosmological neighborhood very well despite the numerous redshift surveys that have been going on in the last decades: dynamically important large-scale structures still remain hidden by the Milky Way. I will present a first description of what we have learned from the still sparsely-sampled Vela Supercluster, as well as the potential implications of this overdensity on the bulk flows, including predictions from flow fields. A first mass overdensity estimate from the to date still sparsely sampled survey implies the Vela SCL to contribute ~ 50 km/s to the motion of the Local Group despite its distance. This will be followed by forthcoming survey plans, including Taipan (spectroscopic) and MeerKAT (HI) in the early science verification phase, to get a more comprehensive census of the Vela SCL, including the most opaque part of the Zone of Avoidance.