2 research outputs found
Discovery of Extreme Examples of Superclustering in Aquarius
We report the discovery of two highly extended filaments and one extremely
high density knot within the region of Aquarius. The supercluster candidates
were chosen via percolation analysis of the Abell and ACO catalogs and include
only the richest clusters (R >= 1). The region examined is a 10x45 degree strip
and is now 87% complete in cluster redshift measurements to mag_10 = 18.3. In
all, we report 737 galaxy redshifts in 46 cluster fields. One of the
superclusters, dubbed Aquarius, is comprised of 14 Abell/ACO clusters and
extends 110h^-1Mpc in length only 7 degrees off the line-of-sight. On the
near-end of the Aquarius filament, another supercluster, dubbed Aquarius-Cetus,
extends for 75h^-1Mpc perpendicular to the line-of-sight. After fitting
ellipsoids to both Aquarius and Aquarius-Cetus, we find axis ratios (long-to-
midlength axis) of 4.3 for Aquarius and 3.0 for Aquarius-Cetus. We fit
ellipsoids to all N>=5 clumps of clusters in the Abell/ACO measured-z cluster
sample. The frequency of filaments with axis ratios >=3.0 (~20%) is nearly
identical with that found among `superclusters' in Monte Carlo simulations of
random and random- clumped clusters, however, so the rich Abell/ACO clusters
have no particular tendency toward filamentation. The Aquarius filament also
contains a `knot' of 6 clusters at Z ~0.11, with five of the clusters near
enough togeteher to represent an apparent overdensity of 150. There are
three other R >= 1 cluster density enhancements similar to this knot at lower
redshifts: Corona Borealis, the Shapely Concentration, and another grouping of
seven clusters in Microscopium. All four of these dense superclusters appear
near the point of breaking away from the Hubble Flow, and some may now be in
collapse, but there is little evidence of any being virialized.Comment: 45 pages (+ e-tables), 7 figures, AASTeX Accepted for Publication in
Ap
The architecture of Abell 1386 and its relationship to the Sloan Great Wall
We present new radial velocities from AAOmega on the Anglo-Australian
Telescope for 307 galaxies (b_J < 19.5) in the region of the rich cluster Abell
1386. Consistent with other studies of galaxy clusters that constitute
sub-units of superstructures, we find that the velocity distribution of A1386
is very broad (21,000--42,000 kms^-1, or z=0.08--0.14) and complex. The mean
redshift of the cluster that Abell designated as number 1386 is found to be
~0.104. However, we find that it consists of various superpositions of
line-of-sight components. We investigate the reality of each component by
testing for substructure and searching for giant elliptical galaxies in each
and show that A1386 is made up of at least four significant clusters or groups
along the line of sight whose global parameters we detail. Peculiar velocities
of brightest galaxies for each of the groups are computed and found to be
different from previous works, largely due to the complexity of the sky area
and the depth of analysis performed in the present work. We also analyse A1386
in the context of its parent superclusters: Leo A, and especially the Sloan
Great Wall. Although the new clusters may be moving toward mass concentrations
in the Sloan Great Wall or beyond, many are most likely not yet physically
bound to it.Comment: 21 pages, 9 figures, includes the full appendix table. Accepted for
publication in MNRA