排序方式: 共有74条查询结果,搜索用时 15 毫秒
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Nicholas Cross Simon P. Driver Warrick Couch Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Matthew Colless Chris Collins Gavin Dalton Kathryn Deeley Roberto De Propris 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 Bruce A. Peterson Ian Price Mark Seaborne Will Sutherland Helen Tadros Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,324(4):825-841
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Edward Conway Steve Maddox Vivienne Wild John A. Peacock Ed Hawkins Peder Norberg Darren S. Madgwick Ivan K. Baldry Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Bryn Jones Ofer Lahav Ian Lewis Stuart Lumsden Will Percival Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2005,356(2):456-474
We present an analysis of the relative bias between early- and late-type galaxies in the Two-degree Field Galaxy Redshift Survey (2dFGRS) – as defined by the η parameter of Madgwick et al., which quantifies the spectral type of galaxies in the survey. We calculate counts in cells for flux-limited samples of early- and late-type galaxies, using approximately cubical cells with sides ranging from 7 to 42 h −1 Mpc . We measure the variance of the counts in cells using the method of Efstathiou et al., which we find requires a correction for a finite volume effect equivalent to the integral constraint bias of the autocorrelation function. Using a maximum-likelihood technique we fit lognormal models to the one-point density distribution, and develop methods of dealing with biases in the recovered variances resulting from this technique. We then examine the joint density distribution function, f (δE , δL ) , and directly fit deterministic bias models to the joint counts in cells. We measure a linear relative bias of ≈1.3, which does not vary significantly with ℓ. A deterministic linear bias model is, however, a poor approximation to the data, especially on small scales (ℓ≤ 28 h −1 Mpc) where deterministic linear bias is excluded at high significance. A power-law bias model with index b 1 ≈ 0.75 is a significantly better fit to the data on all scales, although linear bias becomes consistent with the data for ℓ≳ 40 h −1 Mpc . 相似文献
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Will J. Percival Daniel Burkey Alan Heavens y Taylor Shaun Cole John A. Peacock Carlton M. Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Peder Norberg Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,353(4):1201-1218
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This review summarizes the paleoecology of the Early and Middle Pleistocene of southwestern Asia, based on both flora and fauna, retrieved from a series of ‘windows’ provided by the excavated sites. The incomplete chrono-stratigraphy of this vast region does not allow to accept the direct chronological correlation between the available sites and events of faunal and hominin dispersals from Africa. It also demonstrates that hominins survived in a mixed landscape of open parkland with forested surrounding hills. In addition, the prevailing environmental conditions are not sufficient to explain successful adaptations to new ecological niches away from the African savanna of the bearers of ‘core and flake’ and the Acheulian industries, The differences in knapping and secondary shaping of stone artifacts probably reflect the learned traditions of different groups of hominins. The current distribution of lithic industries across Eurasia is undoubtedly incomplete due to lack of cultural continuities as well as paucity of field research in several sub-regions. This observation supports the contention that what we view as a constant stream of migrants was actually interrupted many times. The continuous occupation of southwestern Asia by the makers of the Acheulian is in contrast with neighboring regions such as the Iranian plateau and Eastern Europe. A more complex model is required to explain the recorded Eurasian archaeological–cultural mosaic. 相似文献
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Attay Kovetz Ofer Yaron Dina Prialnik 《Monthly notices of the Royal Astronomical Society》2009,395(4):1857-1874
We present a new stellar evolution code and a set of results, demonstrating its capability at calculating full evolutionary tracks for a wide range of masses and metallicities. The code is fast and efficient, and is capable of following through all evolutionary phases, without interruption or human intervention. It is meant to be used also in the context of modelling the evolution of dense stellar systems, for performing live calculations for both normal star models and merger products.
The code is based on a fully implicit, adaptive-grid numerical scheme that solves simultaneously for structure, mesh and chemical composition. Full details are given for the treatment of convection, equation of state, opacity, nuclear reactions and mass loss.
Results of evolutionary calculations are shown for a solar model that matches the characteristics of the present sun to an accuracy of better than 1 per cent; a 1 M⊙ model for a wide range of metallicities; a series of models of stellar Populations I and II, for the mass range 0.25 to 64 M⊙ , followed from pre-main-sequence to a cool white dwarf or core collapse. An initial–final mass relationship is derived and compared with previous studies. Finally, we briefly address the evolution of non-canonical configurations, merger products of low-mass main-sequence parents. 相似文献
The code is based on a fully implicit, adaptive-grid numerical scheme that solves simultaneously for structure, mesh and chemical composition. Full details are given for the treatment of convection, equation of state, opacity, nuclear reactions and mass loss.
Results of evolutionary calculations are shown for a solar model that matches the characteristics of the present sun to an accuracy of better than 1 per cent; a 1 M
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D. Heath Jones Mike A. Read Will Saunders Matthew Colless Tom Jarrett Quentin A. Parker Anthony P. Fairall † Thomas Mauch Elaine M. Sadler Fred G. Watson Donna Burton Lachlan A. Campbell Paul Cass Scott M. Croom John Dawe † Kristin Fiegert Leela Frankcombe Malcolm Hartley John Huchra Dionne James Emma Kirby Ofer Lahav John Lucey Gary A. Mamon Lesa Moore Bruce A. Peterson Sayuri Prior Dominique Proust Ken Russell Vicky Safouris Ken-ichi Wakamatsu Eduard Westra Mary Williams 《Monthly notices of the Royal Astronomical Society》2009,399(2):683-698
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 . 相似文献
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Elaine M. Sadler Carole A. Jackson Russell D. Cannon Vincent J. McIntyre Tara Murphy Joss Bland-Hawthorn Terry Bridges Shaun Cole Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Carlos S. Frenk Karl Glazebrook Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick Peder Norberg John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,329(1):227-245
We have cross-matched the 1.4-GHz NRAO VLA Sky Survey (NVSS) with the first 210 fields observed in the 2dF Galaxy Redshift Survey (2dFGRS), covering an effective area of 325 deg2 (about 20 per cent of the final 2dFGRS area). This yields a set of optical spectra of 912 candidate NVSS counterparts, of which we identify 757 as genuine radio identifications – the largest and most homogeneous set of radio source spectra ever obtained. The 2dFGRS radio sources span the redshift range to 0.438, and are a mixture of active galaxies (60 per cent) and star-forming galaxies (40 per cent). About 25 per cent of the 2dFGRS radio sources are spatially resolved by NVSS, and the sample includes three giant radio galaxies with projected linear size greater than 1 Mpc. The high quality of the 2dF spectra means we can usually distinguish unambiguously between AGN and star-forming galaxies. We make a new determination of the local radio luminosity function at 1.4 GHz for both active and star-forming galaxies, and derive a local star formation density of . 相似文献
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The Lyman α forest provides important constraints on the smoothness of the Universe on large scales. We calculate the flux distribution along the line of sight to quasars in a universe made of randomly distributed clumps, each of them with a Rayleigh–L'evy fractal structure with dimension D <2. We consider the probability distribution function of the normalized flux in the line of sight to quasars. We illustrate that the truncated clustering hierarchy model with D <2 shows far too many voids along the line of sight to quasars compared with the observed flux distribution and the distribution in a cold dark matter model. This supports the common view that on large scales the Universe is homogeneous, rather than fractal-like. 相似文献