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تسجيل مستخدم جديدAn HI Survey of the Great Attractor Region
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A blind HI survey using the Parkes telescope at |b|<5 deg, 300 deg < l < 332 deg has so far revealed 305 galaxies, most of which were previously unknown. These galaxies are used to map out the distribution of filaments and voids out to 10000 km/s. A preliminary measurement of the galaxy overdensity suggests only a moderate overdensity is present, and that the excess mass (above the background density) is ~2.10^{15}.Omega.M(sun). This is below the mass predicted in POTENT reconstructions of the local velocity field, and implies that the `Great Attractor (GA) is not as massive as these reconstructions indicate, or does not lie hidden in the region investigated.
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ATCA 21 cm HI observations of the rich galaxy cluster ACO 3627 in the Great Attractor region are presented. Three fields of 30 diameter located within one Abell radius of ACO 3627 were observed with a resolution of 15 and an rms noise of sim 1 mJy/be
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A deep optical galaxy search behind the southern Milky Way and a subsequent redshift survey of the identified obscured galaxies traces clusters and superclusters into the deepest layers of Galactic foreground extinction (A_B <= 3^m - 5^m). In the Gre
at Attractor region, we have identified a low-mass cluster (the Centaurus-Crux cluster) at (l, b, v, sigma) = (305.5deg, +5.5deg, 6214 km/s, 472 km/s) and found that ACO 3627 (the Norma cluster) at (l, b, v, sigma) = (325.3deg, -7.2deg, 4844 km/s, 848 km/s) is the most massive cluster in the Great Attractor region known to date. It is comparable in virial mass, richness and size to the well-known but more distant Coma cluster. The Norma cluster most likely marks the bottom of the potential well of the Great Attractor. It is located at the intersection of two main large-scale structures, the Centaurus Wall and the Norma supercluster. The flow field observed around the Great Attractor probably is caused by the confluence of these two massive structures.
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complete to extinction-corrected magnitudes Ks^o = 14.8 mag for extinctions less than A_K = 1.0 mag and star densities below log N(Ks<14.0) < 4.72. Of the 4360 cataloged galaxies, 99.2% lie in the hereby constrained 89.5% of the survey area. Although the analyzed galaxy distribution reveals no new major galaxy clusters at the GA distance (albeit some more distant ones), the overall number counts and luminosity density indicate a clear and surprisingly smooth overdensity at the GA distance that extends over the whole surveyed region. A mass estimate of the Norma Wall overdensity derived from (a) galaxy number counts and (b) photometric redshift distribution gives a lower value compared to the original prediction by Lynden-Bell et al. 1988 (~14%), but is consistent with more recent independent assessments.
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