A. P. Fairall
University of Cape Town
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Featured researches published by A. P. Fairall.
Monthly Notices of the Royal Astronomical Society | 2009
D. Heath Jones; Mike Read; Will Saunders; Matthew Colless; T. H. Jarrett; Quentin A. Parker; A. P. Fairall; Thomas Mauch; Elaine M. Sadler; Fred G. Watson; D. Burton; Lachlan Campbell; Paul Cass; Scott M. Croom; J. A. Dawe; Kristin Fiegert; Leela M. Frankcombe; Malcolm Hartley; John P. Huchra; Dionne James; Emma M. Kirby; Ofer Lahav; John R. Lucey; Gary A. Mamon; Lesa Moore; Bruce A. Peterson; Sayuri L. Prior; Dominique Proust; K. S. Russell; V. Safouris
We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky (|b| > 10°). Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with (K, H, J, r_F, b_J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75). The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with z ≤ 0.1, showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS.
Monthly Notices of the Royal Astronomical Society | 2008
J. M. Colberg; Frazer R. Pearce; Caroline Foster; Erwin Platen; Riccardo Brunino; Spyros Basilakos; A. P. Fairall; Hume A. Feldman; Stefan Gottlöber; Oliver Hahn; Fiona Hoyle; V. Müller; L. A. Nelson; Manolis Plionis; Cristiano Porciani; Sergei F. Shandarin; Michael S. Vogeley; Rien van de Weygaert
Despite a history that dates back at least a quarter of a century studies of voids in the large–scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void–finding algorithms, a fact that has so far got in the way of groups comparing their results without worrying about whether such a comparison in fact makes sense. Because of the recent increased interest in voids, both in very large galaxy surveys and in detailed simulations of cosmic structure formation, this situation is very unfortunate. We here present the first systematic comparison study of thirteen different void finders constructed using particles, haloes, and semi– analytical model galaxies extracted from a subvolume of the Millennium simulation. The study includes many groups that have studied voids over the past decade. We show their results and discuss their differences and agreements. As it turns out, the basic results of the various methods agree very well with each other in that they all locate a major void near the centre of our volume. Voids have very underdense centres, reaching below 10 percent of the mean cosmic density. In addition, those void finders that allow for void galaxies show that those galaxies follow similar trends. For example, the overdensity of void galaxies brighter than mB = 20 is found to be smaller than about 0.8 by all our void finding algorithms.
Workshop on Unveiling Large-Scale Structures Behind the Milky Way | 1996
A. P. Fairall; Patrick A. Woudt; R. C. Kraan-Korteweg
The band of the Milky Way obscures about 25% of the extragalactic sky. It hides some of the most crucial nearby structures in the large-scale distribution of galaxies. This is especially true in the southern sky where a local overdensity - the “Great Attractor” is believed to exist and is probably mainly responsible for the large-scale steaming motion of our galaxy and neighbouring regions relative to the Cosmic Microwave Background. A recent determination of the centre of the Great Attractor (Dekel 1994) puts it at a redshift of cz=4500 km s-1 in the direction 1=320°, b=0°, right behind the galactic equator, where it is totally obscured, at optical wavelengths, by the dust of the southern Milky Way.
Monthly Notices of the Royal Astronomical Society | 2007
Patrick A. Woudt; R. C. Kraan-Korteweg; John R. Lucey; A. P. Fairall; Steven A. Moore
A detailed dynamical analysis of the nearby rich Norma cluster (ACO 3627) is presented. From radial velocities of 296 cluster members, we find a mean velocity of 4871 ± 54 km s −1 and a velocity dispersion of 925 km s −1 . The mean velocity of the E/S0 population (4979 ± 85 km s −1 ) is offset with respect to that of the S/Irr population (4812 ± 70 km s −1 )b y �v = 164 km s −1 in the cluster rest frame. This offset increases towards the core of the cluster. The E/S0 population is free of any detectable substructure and appears relaxed. Its shape is clearly elongated with a position angle that is aligned along the dominant large-scale structures in this region, the so-called Norma wall. The central cD galaxy has a very large peculiar velocity of 561 km s −1 which is most probably related to an ongoing merger at the core of the cluster. The spiral/irregular galaxies reveal a large amount of substructure; two dynamically distinct subgroups within the overall spiral population have been identified, located along the Norma wall elongation. The dynamical mass of the Norma cluster within its Abell radius is 1‐1.1 × 10 15 h −1 73 M� . One of the cluster members, the spiral galaxy WKK 6176 which recently was observed to have a 70 kpc X-ray tail, reveals numerous striking low-brightness filaments pointing away from the cluster centre suggesting strong interaction with the intracluster medium.
The Astronomical Journal | 1992
A. P. Fairall; Christopher N. A. Willmer; J. H. Calderon; David W. Latham; L. N. da Costa; P. S. Pellegrini; Margarida Nunes; P. Focardi; G. Vettolani
406 redshifts are reported for galaxies in the northern galactic hemisphere, south of δ = 0°. A substantial fraction of the observed galaxies are located in the equatorial zone −17.5° ≤ δ ≤ 0°. By combining these new data with those available in the literature it is possible to extend the original CfA redshift survey of galaxies brighter than m B(0) = 14.5 to b = 30°, south of δ = 0°. New data taken at lower galactic latitudes also contribute to the existing surveys of the Hydra-Centaurus complex
Astrophysics and Space Science | 1995
A. P. Fairall
This article reviews work carried out in South Africa on large-scale structures. It describes the first redshift survey and contributions towards the Southern Sky Redshift Survey and its extension. Surveys of the Hydra-Centaurus region, and behind the adjacent Milky Way, are also discussed. The plots and analyses derived from the “Southern Redshift Catalogue”, as well as very recent work in “visualization”, are presented.
Astrophysics and Space Science | 1995
A. P. Fairall; P. A. Whitelock
At a time when major reforms are shaping the education system of the new South Africa, Astronomy could play a crucial role in the teaching and appreciation of science. There is as yet very little Astronomy in formal school curricula, so extra-mural approaches are necessary. In this regard, initiatives have been made by the astronomical national facilities, while many school pupils visit the two major planetariums. At an advanced level, various universities offer courses and professional training.
Astrophysics and Space Science | 1988
Brian Warner; A. P. Fairall; M. Daniel Overbeek
High-speed photometry, spectroscopy, and visual observations of TU Oph show it to be a Mira variable, not a dwarf nova as originally classified or a UV Cet star as tentatively classified.
Archive | 1984
A. P. Fairall; H. Winkler
Our present understanding of the large scale distribution and super-clustering of galaxies rests mainly on the relative wealth of redshifts obtained in the northern hemisphere. It will be some years before the quantity and quality of redshifts in the southern hemisphere can complement the northern data and correct the imbalance. In the meantime, we wish to offer a preliminary examination using available data — albeit somewhat heterogeneous.
The Astrophysical Journal | 1994
L. Nicolaci da Costa; Margaret J. Geller; P. S. Pellegrini; David W. Latham; A. P. Fairall; R. O. Marzke; Christopher N. A. Willmer; John P. Huchra; J. H. Calderon; M. Ramella; Michael J. Kurtz