Galactosynthesis predictions at high redshift     

Ari Buchalter  Raul Jimenez  Marc Kamionkowski 《Monthly notices of the Royal Astronomical Society》2001,328(2):520-526

We predict the Tully–Fisher (TF) and surface-brightness–magnitude relations for disc galaxies at     and discuss the origin of these scaling relations and their scatter. We find that both halo dynamics and the star formation history play important roles, and we show that the variation of the TF relation with redshift can be a potentially powerful discriminator of galaxy-formation models. In particular, the TF relation at high redshift might be used to break parameter degeneracies among galactosynthesis models at     , as well as to constrain the redshift distribution of collapsing dark-matter haloes, the star formation history and baryon fraction in the disc and the distribution of halo spins.  相似文献   

Self-consistent theory of halo mergers     

Andrew J. Benson  Marc Kamionkowski  Steven H. Hassani 《Monthly notices of the Royal Astronomical Society》2005,357(3):847-858

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The SAURON project – V. Integral-field emission-line kinematics of 48 elliptical and lenticular galaxies     

Marc Sarzi  Jesús Falcón-Barroso  Roger L. Davies  Roland Bacon  Martin Bureau  Michele Cappellari  P. Tim de Zeeuw  Eric Emsellem  Kambiz Fathi  Davor Krajnovi&#;  Harald Kuntschner  Richard M. McDermid  Reynier F. Peletier 《Monthly notices of the Royal Astronomical Society》2006,366(4):1151-1200

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On the Use of HF Surface Wave Radar in Congested Waters: Influence of Masking Effect on Detection of Small Ships     

Rgis Guinvarc'h Marc Lesturgie Rmi Durand Anil Cheraly 《Oceanic Engineering, IEEE Journal of》2006,31(4):894-903

In this paper, we assess the capability of a high-frequency surface wave radar (HFSWR) to detect a small fast boat moving behind a ship, the dimensions of which are comparable to the wavelength. We show that, in the HF-band, the scattered field in the shadow region of the large ship is significant enough to induce strong coupling between the two vessels. This results in fluctuations in the radar cross section (RCS) values of the small boat of about 12 dB at 10 MHz, for instance. We also introduce a complete simulation tool to account for the environment and, thus, to be able to simulate real scenes. We have validated these results through anechoic chamber measurements, with two different masking vessels and three different masked ships. The measurements have shown both the low-attenuation results and the RCS fluctuations  相似文献   

Central stellar populations of early-type galaxies in low-density environments     

Maela Collobert  Marc Sarzi  Roger L. Davies  Harald Kuntschner  Matthew Colless 《Monthly notices of the Royal Astronomical Society》2006,370(3):1213-1222

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Major element and primary sulfur concentrations in Apollo 12 mare basalts: The view from melt inclusions     

Daniel J. BOMBARDIERI  Marc D. NORMAN  Vadim S. KAMENETSKY  Leonid V. DANYUSHEVSKY 《Meteoritics & planetary science》2005,40(5):679-693

Abstract— Major element and sulfur concentrations have been determined in experimentally heated olivine‐hosted melt inclusions from a suite of Apollo 12 picritic basalts (samples 12009, 12075, 12020, 12018, 12040, 12035). These lunar basalts are likely to be genetically related by olivine accumulation (Walker et al. 1976a, b). Our results show that major element compositions of melt inclusions from samples 12009, 12075, and 12020 follow model crystallization trends from a parental liquid similar in composition to whole rock sample 12009, thereby partially confirming the olivine accumulation hypothesis. In contrast, the compositions of melt inclusions from samples 12018, 12040, and 12035 fall away from model crystallization trends, suggesting that these samples crystallized from melts compositionally distinct from the 12009 parent liquid and therefore may not be strictly cogenetic with other members of the Apollo 12 picritic basalt suite. Sulfur concentrations in melt inclusions hosted in early crystallized olivine (Fo₇₅) are consistent with a primary magmatic composition of 1050 ppm S, or about a factor of 2 greater than whole rock compositions with 400–600 ppm S. The Apollo 12 picritic basalt parental magma apparently experienced outgassing and loss of S during transport and eruption on the lunar surface. Even with the higher estimates of primary magmatic sulfur concentrations provided by the melt inclusions, the Apollo 12 picritic basalt magmas would have been undersaturated in sulfide in their mantle source regions and capable of transporting chalcophile elements from the lunar mantle to the surface. Therefore, the measured low concentration of chalcophile elements (e.g., Cu, Au, PGEs) in these lavas must be a primary feature of the lunar mantle and is not related to residual sulfide remaining in the mantle during melting. We estimate the sulfur concentration of the Apollo 12 mare basalt source regions to be ～75 ppm, which is significantly lower than that of the terrestrial mantle.  相似文献   

The SAURON project – XI. Stellar populations from absorption-line strength maps of 24 early-type spirals     

Reynier F. Peletier  Jesús Falcón-Barroso  Roland Bacon  Michele Cappellari  Roger L. Davies  P. T. de Zeeuw  Eric Emsellem  Katia Ganda  Davor Krajnovi&#;  Harald Kuntschner  Richard M. McDermid  Marc Sarzi  Glenn van de Ven 《Monthly notices of the Royal Astronomical Society》2007,379(2):445-468

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How black holes turn cusps into cores     

Marc Hemsendorf 《Astrophysics and Space Science》2003,284(2):561-564

Collapsing collisionless particle systems form gravitational bound halos with cuspy density profiles. Also hierarchical merging of these systems produce remnants with cuspy central density profiles. These results lead to the assumption of cuspy NFW (Navarro et al., 1996) profiles for the density distribution in dark matter halos. However, observed rotation curves in disk galaxies suggest dark matter halos with isothermal cores. The same kind of problem can be found for globular clusters, which show cores in their density profiles but should be cuspy if they where formed through a cold collapse(King, 1962; Jenkins et al., 1998). We are showing how small, massive, and compact objects can efficiently transform cuspy stellar systems into density profiles with an isothermal core. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Rhone River flood deposits in Lake Le Bourget: a proxy for Holocene environmental changes in the NW Alps, France     

Emmanuel Chapron  Fabien Arnaud  HERVÉ Noël  Marie Revel  Marc Desmet  Laurent Perdereau 《Boreas: An International Journal of Quaternary Research》2005,34(4):404-416

The Holocene evolution of Rhone River clastic sediment supply in Lake Le Bourget is documented by sub-bottom seismic profiling and multidisciplinary analysis of well-dated sediment cores. Six high-amplitude reflectors within the lacustrine drape can be correlated to periods of enhanced inter- and underflow deposition in sediment cores. Based on the synthesis of major environmental changes in the NW Alps and on the age-depth model covering the past 7500 years in Lake Le Bourget, periods of enhanced Rhone River flood events in the lake can be related to abrupt climate changes and/or to increasing land use since c. 2700 cal. yr BP. For example, significant land use under rather stable climate conditions during the Roman Empire may be responsible for large flood deposits in the northern part of Lake Le Bourget between AD 966 and 1093. However, during the Little Ice Age (LIA), well-documented major environmental changes in the catchment area essentially resulted from climate change and formed basin-wide major flood deposits in Lake Le Bourget. Up to five 'LIA-like' Holocene cold periods developing enhanced Rhone River flooding activity in Lake Le Bourget are documented at c. 7200, 5200, 2800, 1600 and 200 cal. yr BP. These abrupt climate changes were associated in the NW Alps with Mont Blanc glacier advances, enhanced glaciofluvial regimes and high lake levels. Correlations with European lake level fluctuations and winter precipitation regimes inferred from glacier fluctuations in western Norway suggest that these five Holocene cooling events at 45°N were associated with enhanced westerlies, possibly resulting from a persistent negative mode of the North Atlantic Oscillation.  相似文献   

Multibeam bathymetry and sidescan imaging of the Rivera Transform–Moctezuma Spreading Segment junction, northern East Pacific Rise: New constraints on Rivera–Pacific relative plate motion     

William L. Bandy  Franois Michaud  Jrme Dyment  Carlos A. Mortera-Gutirrez  Jacques Bourgois  Thierry Calmus  Marc Sosson  Jose Ortega-Ramirez  Jean-Yves Royer  Bernard Pontoise  Bertrand Sichler 《Tectonophysics》2008,454(1-4):70-85

To better understand the recent motion of the Pacific plate relative to the Rivera plate and to better define the limitations of the existing Rivera–Pacific plate motion models for accurately predicting this motion, total-field magnetic data, multibeam bathymetric data and sidescan sonar images were collected during the BART and FAMEX campaigns of the N/O L'Atalante conducted in April and May 2002 in the area surrounding the Moctezuma Spreading Segment of the East Pacific Rise, located offshore of Manzanillo, Mexico, at 106°16′W, between 17.8°N and 18.5°N. Among the main results are: (1) the principle transform displacement zone of the Rivera Transform is narrow and well defined east of 107o15′W and these azimuths should be used preferentially when deriving new plate motion models, and (2) spreading rates along the Moctezuma Spreading Segment should not be used in plate motion studies as either seafloor spreading has been accommodated at more than one location since the initiation of seafloor spreading in the area of the Moctezuma Spreading Segment, or this spreading center is not a Rivera–Pacific plate boundary as has been previously assumed. Comparison of observed transform azimuths with those predicted by the best-fit poles of six previous models of Rivera–Pacific relative motion indicate that, in the study area, a significant systematic bias is present in the predictions of Rivera–Pacific motion. Although the exact source of this bias remains unclear, this bias indicates the need to derive a new Rivera–Pacific relative plate motion model.  相似文献