A Catalog of Galaxies behind the Southern Milky Way. - I. The Hydra/Antlia Extension (l: 266 - 296 deg)

A deep optical galaxy search in the southern Milky Way - aimed at reducing the width of the Zone of Avoidance - revealed 3279 galaxy candidates above the diameter limit of D > 0.2 arcmin, of which only 112 (3.4%) were previously catalogued. The surveyed region (266 < l < 296 and -10 < b < +8) lies in the extension of the Hydra and Antlia clusters - where a supercluster is suspected - and in the approximate direction of the dipole anisotropy in the Cosmic Microwave Background radiation. Here we present the optical properties of the unveiled galaxies such as positions, diameters, magnitudes, morphological types, including a detailed discussion on the quality of these data and the completeness limits as a function of the foreground dust extinction. For 127 of the 227 positional matches in the IRAS PSC, a reliable cross-identification could be found. Several distinct overdensities and filaments of galaxies can be identified that are apparently uncorrelated with the Galactic foreground extinction hence the probable signature of extragalactic large-scale structures. This catalog constitutes the first part in a series of five equally conducted optical searches for galaxies in the southern Milky Way (245 < l < 350). With these surveys, the entire Zone of Avoidance will have been covered by means of visual inspection. The catalogs build the basis for various spectroscopic and photometric follow-up programs which eventually will allow a thorough analyse of the galaxy distribution in redshift space and the peculiar velocity fields within the Zone of Avoidance, as well an an improved understanding of the Galactic foreground extinction.Comment: Accepted for publication by A&ASS, 50 pages, LaTex, 7 encapsulated figures, requires aa.cls end epsf.sty. Full-resolution, color figures 1, 2, 6 and 7 are available upon request (E-mail: [email protected]

Cosmological Structures behind the Milky Way

This paper provides an update to the review on extragalactic large-scale structures uncovered in the Zone of Avoidance (ZOA) by Kraan-Korteweg & Lahav 2000, in particular in the Great Attractor region. Emphasis is given to the penetration of the ZOA with the in 2003 released NIR 2MASX Catalog. The distribution is little affected by the foreground dust. Galaxies can be identified to extinction levels of over A(B) < 10m except in the wider Galactic Bulge region (see Fig. 9) where star density is a strong delimiting factor. The shape of the NIR-ZOA is quite asymmetric due to Galactic features such as spiral arms and the Bulge, something that should not be ignored when using NIR samples for studies such as dipole determinations. Results are presented from the deep blind HI ZOA survey performed with the Multibeam Receiver at the Parkes telescope (v < 12700km/s). The distribution of the roughly one thousand discovered spiral galaxies in the optically and NIR impenetratable part of the ZOA clearly depict the prominence of the Norma Supercluster. With the optically identified galaxies in the ZOA, a picture emerges that bears a striking resemblance to the Coma cluster in the Great Wall: the rich Norma cluster (ACO 3627) lies within a great-wall like structure that can be traced at the redshift range of the cluster over 90dg on the sky, with two foreground filaments - reminiscent of the legs in the famous stick man - that merge in an overdensity at slightly lower redshifts around the radio galaxy PKS 1343-601 (see Figs. 14 & 16). (abridged)Comment: Invited Review at the joint conference of the Czech Astron. Society and the Astron. Gesellschaft. To appear in Reviews in Modern Astronomy 18, on ``From Cosmological Structures to the Milky Way'', ed. S. Roeser, 30pages, 16 ps-figures. Full resolution gzipped ps-version (16Mb) available at http://mensa.ast.uct.ac.za/~kraan/AGreview/AGreview.ps.g