共查询到20条相似文献,搜索用时 15 毫秒
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Gordon T. Richards Scott M. Croom Scott F. Anderson Joss Bland-Hawthorn Brian J. Boyle Roberto De Propris Michael J. Drinkwater Xiaohui Fan James E. Gunn eljko Ivezi Sebastian Jester Jon Loveday Avery Meiksin Lance Miller Adam Myers Robert C. Nichol Phil J. Outram Kevin A. Pimbblet Isaac G. Roseboom Nic Ross Donald P. Schneider Tom Shanks Robert G. Sharp Chris Stoughton Michael A. Strauss Alexander S. Szalay Daniel E. Vanden Berk Donald G. York 《Monthly notices of the Royal Astronomical Society》2005,360(3):839-852
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P.J. Outram R.J. Smith T. Shanks B.J. Boyle S.M. Croom N.S. Loaring L. Miller 《Monthly notices of the Royal Astronomical Society》2001,328(3):805-809
We examine the highest signal-to-noise ratio spectra from the 2dF QSO Redshift Survey (2QZ) 10k release and identify over 100 new low-ionization heavy-element absorbers: damped Lyman α (DLA) candidates suitable for higher-resolution follow-up observations. These absorption systems map the spatial distribution of high- z metals in exactly the same volumes as the foreground 2QZ QSOs themselves sample and hence the 2QZ gives us the unique opportunity to compare directly the two tracers of large-scale structure. We examine the cross-correlation of the two populations to see how they are relatively clustered, and, by considering the colour of the QSOs, detect a small amount of dust in these metal systems. 相似文献
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Matthew Colless Gavin Dalton Steve Maddox Will Sutherland Peder Norberg Shaun Cole Joss Bland-Hawthorn Terry Bridges Russell Cannon Chris Collins Warrick Couch Nicholas Cross Kathryn Deeley Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Darren Madgwick John A. Peacock Bruce A. Peterson Ian Price Mark Seaborne Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,328(4):1039-1063
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Roberto De Propris Warrick J. Couch Matthew Colless Gavin B. Dalton Chris Collins Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Nicholas Cross Kathryn Deeley Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick Stephen Moody Peder Norberg John A. Peacock Will Percival Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,329(1):87-101
We have carried out a study of known clusters within the 2dF Galaxy Redshift Survey (2dFGRS) observed areas and have identified 431 Abell, 173 APM and 343 EDCC clusters. Precise redshifts, velocity dispersions and new centroids have been measured for the majority of these objects, and this information is used to study the completeness of these catalogues, the level of contamination from foreground and background structures along the cluster's line of sight, the space density of the clusters as a function of redshift, and their velocity dispersion distributions. We find that the Abell and EDCC catalogues are contaminated at the level of about 10 per cent, whereas the APM catalogue suffers only 5 per cent contamination. If we use the original catalogue centroids, the level of contamination rises to approximately 15 per cent for the Abell and EDCC catalogues, showing that the presence of foreground and background groups may alter the richness of clusters in these catalogues. There is a deficiency of clusters at that may correspond to a large underdensity in the Southern hemisphere. From the cumulative distribution of velocity dispersions for these clusters, we derive a space density of clusters of This result is used to constrain models for structure formation; our data favour low-density cosmologies, subject to the usual assumptions concerning the shape and normalization of the power spectrum. 相似文献
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Manuel Merchán Ariel Zandivarez 《Monthly notices of the Royal Astronomical Society》2002,335(1):216-222
We construct a galaxy groups catalogue from the public 100-K data release of the 2dF Galaxy Redshift Survey. The group identification is carried out using a slightly modified version of the group-finding algorithm developed by Huchra & Geller. Several tests using mock catalogues allow us to find the optimal conditions to increase the reliability of the final group sample. A minimum number of four members, an outer number density enhancement of 80 and a linking radial cut-off of 200 km s−1 are the best obtained values from the analysis. Using these parameters, approximately 90 per cent of groups identified in real space have a redshift space counterpart. On the other hand, the level of contamination in redshift space reaches 30 per cent, including ∼6 per cent of artificial groups and ∼24 per cent of groups associated with binaries or triplets in real space. The final sample comprises 2209 galaxy groups covering the sky region described by Colless et al.spanning over the redshift range of 0.003 ≤ z ≤ 0.25 with a mean redshift of 0.1. 相似文献