The SCUBA Half Degree Extragalactic Survey – IV. Radio–mm–FIR photometric redshifts     

Itziar Aretxaga  David H. Hughes  Kristen Coppin  Angela M. J. Mortier  Jeff Wagg  James S. Dunlop  Edward L. Chapin  Stephen A. Eales  Enrique Gaztañaga  Mark Halpern  Rob J. Ivison  Eelco van Kampen  Douglas Scott  Stephen Serjeant  Ian Smail  Thomas Babbedge  rew J. Benson  Scott Chapman  David L. Clements  Loretta Dunne  Simon Dye  Duncan Farrah  Matt J. Jarvis  Robert G. Mann  Alexandra Pope  Robert Priddey  Steve Rawlings  Marc Seigar  Laura Silva  Chris Simpson  Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2007,379(4):1571-1588

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The contribution of the first stars to the cosmic infrared background     

Michael R. Santos  Volker Bromm  Marc Kamionkowski 《Monthly notices of the Royal Astronomical Society》2002,336(4):1082-1092

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Tests for primordial non-Gaussianity     

Licia Verde  Raul Jimenez  Marc Kamionkowski  Sabino Matarrese 《Monthly notices of the Royal Astronomical Society》2001,325(1):412-418

We investigate the relative sensitivities of several tests for deviations from Gaussianity in the primordial distribution of density perturbations. We consider models for non-Gaussianity that mimic that which comes from inflation as well as that which comes from topological defects. The tests we consider involve the cosmic microwave background (CMB), large-scale structure, high-redshift galaxies, and the abundances and properties of clusters. We find that the CMB is superior at finding non-Gaussianity in the primordial gravitational potential (as inflation would produce), while observations of high-redshift galaxies are much better suited to find non-Gaussianity that resembles that expected from topological defects. We derive a simple expression that relates the abundance of high-redshift objects in non-Gaussian models to the primordial skewness.  相似文献   

Blending-Based Stochastic Simulator     

J. L. Mallet  A. Shtuka 《Mathematical Geology》2000,32(3):367-379

This paper presents a new method of constructing random functions whose realizations can be evaluated efficiently. The basic idea is to blend, both stochastically and linearly, a limited set of independent initial realizations previously generated by any chosen simulation method. The blending stochastic coefficients are determined in such a way that the new random function so generated has the same mean and covariance functions as the random function used for generating the initial realizations.  相似文献   

Intrinsic and extrinsic galaxy alignment     

Paolo Catelan  Marc Kamionkowski  Roger D. Blandford 《Monthly notices of the Royal Astronomical Society》2001,320(1):L7-L13

We show with analytic models that the assumption of uncorrelated intrinsic ellipticities of target sources that is usually made in searches for weak gravitational lensing arising from large-scale mass inhomogeneities ('field lensing') is unwarranted. If the orientation of the galaxy image is determined either by the angular momentum or by the shape of the halo in which it forms, then the image should be aligned preferentially with the component of the tidal gravitational field perpendicular to the line of sight. Long-range correlations in the tidal field will thus lead to long-range ellipticity–ellipticity correlations that mimic the shear correlations arising from weak gravitational lensing. We calculate the ellipticity–ellipticity correlation expected if halo shapes determine the observed galaxy shape, and we discuss uncertainties (which are still considerable) in the predicted amplitude of this correlation. The ellipticity–ellipticity correlation induced by angular momenta should be smaller. We consider several methods for discriminating between the weak-lensing (extrinsic) and intrinsic correlations, including the use of redshift information. An ellipticity–tidal-field correlation also implies the existence of an alignment of images of galaxies near clusters. Although the intrinsic alignment may complicate the interpretation of field-lensing results, it is inherently interesting as it may shed light on galaxy formation as well as on structure formation.  相似文献   

An optimum method for calculating restricted three-body orbits     

Marc A. Murison 《Celestial Mechanics and Dynamical Astronomy》1988,45(1-3):175-180

The restricted three-body problem (RTBP) has in the past played an essential role in many different areas of dynamical astronomy, and indications are that this will continue. As the state of the art in computing becomes more advanced, larger numbers of integrations and longer durations are attempted. Thus, computational efficiency and accuracy are becoming more important. Also, the use of the RTBP in many different areas leads to the desire for a general integration method.In order to maximize the efficiency of orbit calculations, comparisons are made of different methods of integration. The results can be summarized as follows: 1. The Bulirsch-Stoer extrapolation method is extremely fast and accurate, and is the method of choice. 2. Regularization of the equations of motion is essential. 3. When applicable, a manifold correction algorithm, originally due to Nacozy (1971), reduces numerical errors to the limits of machine accuracy, and at a cost of only 1 to 3 percent in cpu time.  相似文献   

Test of tectonic models by great circle Rayleigh waves     

Annie Souriau  Marc Souriau 《Geophysical Journal International》1983,73(2):533-551

Summary. A large set of published great circle Rayleigh wave phase velocities in the period range 125–350s is used to compare three recent tectonic models (Okal, Lévêque, Jordan). Prior to any regionalization, the symmetry property of the great circle integrals is used to obtain a lower limit of the signal/noise ratio in the data. It turns out that the signal is responsible for at least 30 per cent of the data variance in the period range 175–300s.
A standard regression method is applied for computing the'pure path'velocities and the model efficiency is derived from a variance analysis. It is shown that, even at great depth, none of the three models explains more than 60 per cent of the energy due to the long-wavelength lateral heterogeneities (λ6500 km).
The three models have nearly the same efficiency for explaining the short-period data ( T ∼ 125s). Between 200 and 300s, the higher performance of Okal's model indicates that it is important to separate the subduction zones from the other orogenic zones. By perturbing the lateral extension of the subduction zones, it comes out that they constitute on both sides of the subducting slabs wider anomalies than often assumed, suggesting large downgoing flows. On the contrary, the effect of surface features such as marginal seas are restricted to a close region in front of the trenches.
Finally, the anomalous ellipticity values deduced directly from great circle data are partly explained by a coupling between tectonics and ellipticity.  相似文献   

A mantle plume origin for the Siberian traps: uplift and extension in the West Siberian Basin, Russia   总被引：9，自引：0，他引：9  

Andrew D. Saunders  Richard W. England  Marc K. Reichow  Rosalind V. White 《Lithos》2005,79(3-4):407-424

The West Siberian Basin (WSB) records a detailed history of Permo-Triassic rifting, extension and volcanism, followed by Mesozoic and Cenozoic sedimentation in a thermally subsiding basin. Sedimentary deposits of Permian age are absent from much of the basin, suggesting that large areas of the nascent basin were elevated and exposed at that time. Industrial seismic and well log data from the basin have enabled extension and subsidence modelling of parts of the basin. Crustal extension (β) factors are calculated to be in excess of 1.6 in the northern part of the basin across the deep Urengoy graben. 1-D backstripping of the Triassic to Cenozoic sedimentary sequences in this region indicates a period of delayed subsidence during the early Mesozoic. The combination of elevation, rifting and volcanism is consistent with sublithospheric support, such as a hot mantle plume.

This interpretation accords with the geochemical data for basalts from the Siberian Traps and the West Siberian Basin, which are considered to be part of the same large igneous province. Whilst early suites from Noril'sk indicate moderate pressures of melting (mostly within the garnet stability field), later suites (and those from the West Siberian Basin) indicate shallow average depths of melting. The main region of magma production was therefore beneath the relatively thin (ca. 50–100 km) lithosphere of the basin, and not the craton on which the present-day exposure of the Traps occurs. The indicated uplift, widespread occurrence of basalts, and short duration of the volcanic province as a whole are entirely consistent with published models involving a mantle plume. The main argument against the plume model, namely lack of any associated uplift, appears to be untenable.  相似文献   

Geochemistry and petrogenesis of basalts from the West Siberian Basin: an extension of the Permo–Triassic Siberian Traps, Russia     

Marc K. Reichow  A.D. Saunders  R.V. White  A.I. Al'Mukhamedov  A.Ya. Medvedev 《Lithos》2005,79(3-4):425-452

New major and trace element data for the Permo–Triassic basalts from the West Siberian Basin (WSB) indicate that they are strikingly similar to the Nadezhdinsky suite of the Siberian Trap basalts. The WSB basalts exhibit low Ti/Zr (50) and low high-field-strength element abundances combined with other elemental characteristics (e.g., low Mg#, and negative Nb and Ti anomalies on mantle-normalised plots) typical of fractionated, crustally contaminated continental flood basalts (CFBs). The major and trace element data are consistent with a process of fractional crystallisation coupled with assimilation of incompatible-element-enriched lower crust. Relatively low rates of assimilation to fractional crystallisation (0.2) are required to generate the elemental distribution observed in the WSB basalts. The magmas parental to the basalts may have been derived from source regions similar to primitive mantle (OIB source) or to the Ontong Java Plateau source. Trace element modelling suggests that the majority of the analysed WSB basalts were derived by large degrees of partial melting at pressures less than 3 GPa, and therefore within the garnet-spinel transition zone or the spinel stability field.

It seems unlikely that large-scale melting in the WSB was induced through lithospheric extension alone, and additional heating, probably from a mantle plume, would have been required. We argue that the WSB basalts are chemically and therefore genetically related to the Siberian Traps basalts, especially the Nadezhdinsky suite found at Noril'sk. This suite immediately preceded the main pulse of volcanism that extruded lava over large areas of the Siberian Craton. Magma volume and timing constraints strongly suggest that a mantle plume was involved in the formation of the Earth's largest continental flood basalt province.  相似文献   

Évolution récente et actuelle de la côte basque française (analyse et perspectives)     

Antonin Genna  Jean-Pierre Capdeville  Jacques Dubreuilh  Cyril Mallet 《Comptes Rendus Geoscience》2005,337(16):1474

A recent multidisciplinary study, comprising existing data analysis and geomorphological and geological fieldwork, has helped clarify marine erosion processes of Pyrenean formations along the Basque Coast. An important discovery was made during our study of an alterite of regional extent, which calls into question recent and present evolution of the Basque Coast and the processes leading to coastline retreat. Modelling these factors has made it possible to propose a predictive scenario for future coastal evolution. To cite this article: A. Genna et al., C. R. Geoscience 337 (2005).  相似文献