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101.
Alexander Knebe Chris Power Stuart P. D. Gill Brad K. Gibson 《Monthly notices of the Royal Astronomical Society》2006,368(2):741-750
We investigate the importance of interactions between dark matter substructures for the mass loss they suffer whilst orbiting within a sample of high-resolution galaxy cluster mass cold dark matter (CDM) haloes formed in cosmological N -body simulations. We have defined a quantitative measure that gauges the degree to which interactions are responsible for mass loss from substructures. This measure indicates that interactions are more prominent in younger systems when compared to older more relaxed systems. We show that this is due to the increased number of encounters a satellite experiences and a higher mass fraction in satellites. This is in spite of the uniformity in the distributions of relative distances and velocities of encounters between substructures within the different host systems in our sample.
Using a simple model to relate the net force felt by a single satellite to the mass loss it suffers, we show that interactions with other satellites account for ∼30 per cent of the total mass loss experienced over its lifetime. The relation between the age of the host and the importance of interactions increases the scatter about this mean value from ∼25 per cent for the oldest to ∼45 per cent for the youngest system we have studied. We conclude that satellite interactions play a vital role in the evolution of substructure in dark matter haloes and that a significant fraction of the tidally stripped material can be attributed to these interactions. 相似文献
Using a simple model to relate the net force felt by a single satellite to the mass loss it suffers, we show that interactions with other satellites account for ∼30 per cent of the total mass loss experienced over its lifetime. The relation between the age of the host and the importance of interactions increases the scatter about this mean value from ∼25 per cent for the oldest to ∼45 per cent for the youngest system we have studied. We conclude that satellite interactions play a vital role in the evolution of substructure in dark matter haloes and that a significant fraction of the tidally stripped material can be attributed to these interactions. 相似文献
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103.
William S. Burgett Michael M. Vick David S. Davis Matthew Colless Roberto De Propris Ivan Baldry Carlton Baugh Joss Bland-Hawthorn Terry Bridges Russell Cannon Shaun Cole Chris Collins Warrick Couch Nicholas Cross Gavin Dalton Simon Driver George Efstathiou Richard Ellis Carlos S. Frenk Karl Glazebrook Edward Hawkins Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick Peder Norberg John A. Peacock Will Percival Bruce Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,352(2):605-654
104.
C. Dorbath L. Dorbath J. D. Fairhead G. W. Stuart 《Geophysical Journal International》1986,86(3):751-766
Summary. P -wave relative teleseismic residuals were measured for a network of seismological stations along a 300 km profile across the Adamawa Plateau and the Central African Shear Zone of central Cameroon, to determine the variation in crust and upper mantle velocity associated with these structures. A plot of the mean relative residuals for the stations shows a long wavelength (> 300 km) variation of amplitude 0.45 s. the slowest arrivals are located over and just to the north, of the faulted northern margin of the Adamawa Plateau. the residuals do not correlate with topography, surface geology or the previously determined crustal structure, in any simple way.
The Aki inversion technique has been used to invert the relative residuals into a 3-D model of velocity perturbations from a mean earth model. the results show the region is divided roughly into three blocks by two subvertical boundaries, striking ENE and traversing both the crust and upper mantle down to depths greater than 190km. the central block, which is 2 per cent slower than the adjacent blocks, roughly corresponds to the Central African Shear Zone. the Adamawa Plateau, as an individual uplifted area, is explained by the interaction of a regional anomalous upper mantle associated with the West African Rift System, and the Central African Shear Zone, which provided a conduit for heat flow to the surface. 相似文献
The Aki inversion technique has been used to invert the relative residuals into a 3-D model of velocity perturbations from a mean earth model. the results show the region is divided roughly into three blocks by two subvertical boundaries, striking ENE and traversing both the crust and upper mantle down to depths greater than 190km. the central block, which is 2 per cent slower than the adjacent blocks, roughly corresponds to the Central African Shear Zone. the Adamawa Plateau, as an individual uplifted area, is explained by the interaction of a regional anomalous upper mantle associated with the West African Rift System, and the Central African Shear Zone, which provided a conduit for heat flow to the surface. 相似文献
105.
Stuart A. Hall 《Geophysical Journal International》1979,58(3):583-592
Summary. Estimates of the secular variation in the Red Sea over the period 1959 to 1972 have been obtained from an analysis of marine magnetic data. A total of 318 crossings of ships' tracks were used to determine the mean secular variation for the intervals 1959–72, 1959–65 and 1965–72. The mean secular variation 1959–72 shows a marked northward increase from approximately -10 nT/yr at 13°N to +27 nT/yr at 24°N. North of this, the data suggest a small decrease to + 25 nT/yr at 27° N. These values are consistent with the secular variation recorded at the nearby geomagnetic observatory at Helwan, Egypt, but less than those predicted by the 1965 IGRF for the same period.
Comparison of the mean secular variations for 1959–65 and 1965–72 yields a rough estimate of the secular acceleration of - 1.5 nT yr−2 . Analysis of the cross-over information, corrected for the latitude dependence of the secular variation, shows a regular decrease in the secular change over the period 1959–72 at all latitudes of about -1 nTyr−2 . This secular acceleration makes a substantial contribution to the overall secular change in the Red Sea and as such must be included in the correction of magnetic data covering more than a few years. 相似文献
Comparison of the mean secular variations for 1959–65 and 1965–72 yields a rough estimate of the secular acceleration of - 1.5 nT yr
106.
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109.
Parasitic programs for the Search for Extraterrestrial Intelligence (SETI), carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. We describe a microprocessor-based automated SETI acquisition system which searches for and records spectra of narrowband signals in the IF band of an observatory receiver. Data taken with this system over 35 days at the Hat Creek Radio Observatory at 1612 MHz are discussed. Out of approximately 105 spectra processed during this period, 4000 were identified by the system as containing narrowband signals and were recorded. Subsequent analysis indicates that over 3900 of these are due to local RF contamination. The remainder are undergoing further investigation. 相似文献
110.