![]() | Annu. Rev. Astron. Astrophys. 1991. 29:
499-541 Copyright © 1991 by Annual Reviews. All rights reserved |
3.3 3-D Surveys
Wide-angle surveys designed to sample a specific volume are the best for topological studies of the three-dimensional structure. Such surveys can have practical restrictions imposed by galactic extinction, sky coverage of the telescope used, and limits of the target catalog, usually in apparent magnitude, flux, or diameter, and may also be restricted by morphology or surface brightness constraints on detectability. Each survey must then be evaluated in light of the biases introduced by the selection process. Below, we discuss the major three-dimensional surveys.
THE LOCAL SUPERCLUSTER SURVEY
THE CFA SURVEY
THE PISCES-PERSEUS SURVEY
THE SOUTHERN SKY REDSHIFT SURVEY (SSRS)
THE IRAS SURVEY
> -
45°, they selected large-angular-diameter objects of spiral or
irregular morphology, which upon visual
inspection on the Palomar Observatory and Whiteoak Extension Sky Surveys
(POSS) appeared to be nearby. While this survey revealed in great detail
the structure of the Local Supercluster, it is manifestly incomplete for
early morphological types and for distances beyond 1000 km
s-1. However
this survey, which contributed 1171 new redshifts, was the largest in
scope at the time and marked the entrance of the 21-cm line as a main
performer in the study of large-scale structure.
Tully & Fisher (1987)
more recently produced a detailed picture of the structure of the Local
Supercluster, with the additional inclusion principally of earlytype
galaxies of
Sandage (1978).
0°, b
40°, in the
northern galactic gap, and
- 2.5°, b
- 30°, in the southern one.
The CfA survey compilation
(Huchra et al 1983)
lists 2401 redshifts;
nearly 60% of which were contributed by the CfA group using the 1.5-m
Tillinghast reflector at Mt. Hopkins, an instrument since dedicated to
the CfA redshift effort. The CfA survey has been used by many authors as
the basis of statistical studies of the three-dimensional distribution
of galaxies, the distribution and nature of galaxy groups, and the
characteristics of galaxy segregation.
Huchra (1988)
has given a review of the CfA effort and the results derived from it.
10° and
0°. This sample
includes all CGCG galaxies (to m = 15.7) and all those of UGC size 1' or
greater within the sampled region. They inspected and classified non-UGC
galaxies on the POSS, and observed at 21 cm (primarily at Arecibo and
with the Green Bank 300-foot telescope outside of the Arecibo horizon)
all galaxies of types S0a or later. Galaxies of earlier types of unknown
redshift and spirals undetected at 21 cm were observed at the
McGraw-Hill 2.4-m optical telescope. The overall sample is better than
85% complete; the weakest areas-with completion rates near 65% -
correspond to the regions north of
= + 35° and south of
= 3°,
reflecting zenithal limitations of the Arecibo antenna currently in the
process of correction. This effort has contributed new redshifts for
approximately 3500 galaxies.
Giovanelli (1990)
summarizes recent findings. Haynes & Giovanelli
(1986,
1988)
review analyses of the
large-scale structural properties of this region. Topological details
are described by
Giovanelli et al
(1986a),
Gott et al (1989), and
Ryden et al (1989).
Void probability statistics are described by
Fry et al (1989).
Merighi et al (1986)
survey neighboring areas, and
Maurogordato et al
(1990)
map the extension of the supercluster towards southern declinations.
=
- 17.5° and below b = - 30°. Because
Lauberts' catalog was not photometrically complete, da Costa et al
selected objects based on an angular size, given by log -
D(0)lim > 0.1,
where D(0) is a diameter in arc minutes, corrected to face-on
appearance. A conversion of this limit to one of apparent magnitude
would depend upon morphological type, but on the average the depth of
this sample is comparable to a blue mlim
14.8.
Da Costa et al (1989)
have extended the SSRS effort to a second region of 135° x
10°, south of
b = -30° and at -40°
-30°. Converting Lauberts' diameters to a
magnitude scale, they have surveyed galaxies earlier than Sbc to a blue
magnitude limit of 15.1, and are currently reaching completion to 15.5
in that region. A detailed graphic analysis of the galaxian distribution
in the southern galactic cap is given by
Pellegrini et al
(1990).