Includes bibliographical references / As part of a larger effort to uncover the structures hidden behind the Milky Way, we analyse 5,190 spectroscopic redshifts for galaxies in the Hydra/Antlia and Vela regions (245°≤ l ≤ 295°, /b/ ≤ 10°). These galaxies are based on deep optical galaxy source catalogues in the Zone of Avoidance in the Hydra/Antlia region (Kraan-Korteweg 2000a), the Vela region (von Maltitz 2012), and the near infrared 2MASS Extended Source Catalogue(XSC) (Jarrett et al. 2000a, Skrutskie et al. 2006). The observed redshifts were mainly obtained from the 2dF+ AAOmega spectrograph at the Anglo-Australian Telescope (80% of the redshifts); the remaining data are from other telescopes as well as from the literature. This analysis is suggestive of the existence of a massive supercluster in this region, hereafter called the Vela Supercluster (VSC). The prospective VSC is at a mean redshift of cz ~18, 000km s⁻¹, and extends approximately about 87 x 87Mpc on-sky. We use a nearest neighbour algorithm to identify the galaxy clusters and groups within the potential VSC, determine their velocity dispersions and the corresponding virial masses. Although the VSC is sparsely sampled, we find 13 galaxy clusters and 22 galaxy groups contained within it. The richness and the masses of these galaxy clusters/groups are comparable with the galaxy clusters/groups found within the Shapley Supercluster by Proust et al. (2006). Taking account of the sparse sampling, the VSC seems comparable to the Shapley Supercluster (SSC). Given the fact that the SSC contributes about 9% of the Local Group motion (Muñoz & Loeb 2008), if not more (see Kocevski & Ebeling 2006). The proximity of a further supercluster (VSC) in its vicinity, might have serious implications on the bulk flows studies. Consequently, the existence of this supercluster is likely key in resolving the long-enduring bulk flow controversies and the misalignment of flows with the dipole determined via the Cosmic Microwave Background (CMB) observations.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uct/oai:localhost:11427/16540 |
| Date | January 2015 |
| Creators | Elagali, Ahmed |
| Contributors | Kraan-Korteweg, Renée C, Cluver, Michelle E |
| Publisher | University of Cape Town, Faculty of Science, Department of Astronomy |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Master Thesis, Masters, MSc |
| Format | application/pdf |
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