The fossil phase in the life of a galaxy group     

Alexander M. von Benda-Beckmann  Elena D'Onghia †  Stefan Gottlöber  Matthias Hoeft  Arman Khalatyan  Anatoly Klypin  Volker Müller 《Monthly notices of the Royal Astronomical Society》2008,386(4):2345-2352

We investigate the origin and evolution of fossil groups in a concordance ΛCDM cosmological simulation. We consider haloes with masses between  1 × 10¹³  and  5 × 10¹³  h ⁻¹ M_⊙  , and study the physical mechanisms that lead to the formation of the large gap in magnitude between the brightest and the second most bright group member, which is typical for these fossil systems. Fossil groups are found to have high dark matter concentrations, which we can relate to their early formation time. The large magnitude gaps arise after the groups have built up half of their final mass, due to merging of massive group members. We show that the existence of fossil systems is primarily driven by the relatively early infall of massive satellites, and that we do not find a strong environmental dependence for these systems. In addition, we find tentative evidence for fossil group satellites falling in on orbits with typically lower angular momentum, which might lead to a more efficient merger on to the host. We find a population of groups at higher redshifts that go through a 'fossil phase': a stage where they show a large magnitude gap, which is terminated by renewed infall from their environment.  相似文献   

Properties of low‐frequency trapped mode in viscous‐fluid waveguides          下载免费PDF全文

Anatoly A. Nikitin  Boris D. Plyushchenkov  Arkady Yu. Segal 《Geophysical Prospecting》2016,64(5):1335-1349

We derived the velocity and attenuation of a generalized Stoneley wave being a symmetric trapped mode of a layer filled with a Newtonian fluid and embedded into either a poroelastic or a purely elastic rock. The dispersion relation corresponding to a linearized Navier–Stokes equation in a fracture coupling to either Biot or elasticity equations in the rock via proper boundary conditions was rigorously derived. A cubic equation for wavenumber was found that provides a rather precise analytical approximation of the full dispersion relation, in the frequency range of 10^?3 Hz to 10³ Hz and for layer width of less than 10 cm and fluid viscosity below 0.1 Pa· s [100 cP]. We compared our results to earlier results addressing viscous fluid in either porous rocks with a rigid matrix or in a purely elastic rock, and our formulae are found to better match the numerical solution, especially regarding attenuation. The computed attenuation was used to demonstrate detectability of fracture tip reflections at wellbore, for a range of fracture lengths and apertures, pulse frequencies, and fluid viscosity.  相似文献   

Land Aridization in the Context of Global Warming - a Case Study of Transbaikalia     

Anatoly I. KULIKOV  Bair Z. TSYDYPOV  Bator V. SODNOMOV  Ayur B. GYNINOVA  WANG Juanle 《资源与生态学报(英文版)》2017,8(2):141-147

An increase in the extremality of natural processes is a consequence of warming, aridization, and desertification. The authors consider the processes of warming, aridization, and desertification to be the parts of a single system and major destabilizing factors of ecological balance. Destabilization is expressed in the growth of natural processes extremality. Ecosystems of Transbaikalia were once characterized by a different natural contrast and amplitude. Warming, aridization and desertification have led to an increase of environmental regimes tensions. This is demonstrated quantitatively by the root-mean-square difference of atmospheric and soil parameters. Quantitative indicators of aridization are estimated using Walter-Gossen climate charts. Permafrost zone response information to the long-term warming is provided as well.  相似文献   

Lithospheric stress in Mongolia,from earthquake source data     

Demberel Sodnomsambuu  Anatoly V. Klyuchevskii 《地学前缘(英文版)》2017,8(6):1323-1337

Lithospheric stress in Mongolia has been studied using mechanisms of 84 M_(LH)≥ 4 earthquakes that occurred in the 20 th century and instrumental seismic moments of 17,375 M_(LH)≥2.5 events recorded between 1970 and 2000.The M_(LH)≥ 3.5 earthquakes mostly have strike-slip mechanisms in southern and central Mongolia,with frequent reverse-slip motions in the west and normal slip in the north,especially,in the area of Lake Hovsgol.The principal stresses are,respectively,S_HS_vS_h in the center and in the south;high horizontal compression with S_HS_hS_v in the west;and a heterogeneous stress pattern with S_vS_HS_h in the north.According to seismic moments of M_(LH)=2.5 events,oblique slip generally predominates over the territory,at S_v≈S_HS_h,while frequent strike slip motions in the west record high horizontal compression(S_HS_vS_h).Earthquake mechanisms show the principal horizontal compression S_H to be directed W-E in the east,NE-SW in the central and Gobi-Altay regions,and approximately N-S in the west of Mongolia.The patterns of principal lithospheric stresses in the territory of Mongolia have undergone three events of dramatic change for a few recent decades,and these events were synchronous with three similar events in the Baikal rift system(BRS):in the latest 1960 s,latest 1970 s to earliest 1980 s,and in the latest 1980 s to earliest 1990 s.The seismicity of Mongolia has been controlled by superposition of variable stresses associated with rifting activity pulses in the neighbor BRS on the background of quasi-stationary super-regional compression.  相似文献   

Investigation of sedimentary aquifers in Denmark using the magnetic resonance sounding method (MRS)     

Konstantinos Chalikakis  Mette Ryom Nielsen  Anatoli Legchenko  Tom Feldberg Hagensen 《Comptes Rendus Geoscience》2009,341(10-11):918-927

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Interpretation of magnetic resonance soundings in rocks with high electrical conductivity   总被引：1，自引：0，他引：1  

A. Legchenko  M. Ezersky  J.-F. Girard  J.-M. Baltassat  M. Boucher  C. Camerlynck  A. Al-Zoubi   《Journal of Applied Geophysics》2008,66(3-4):118

Magnetic resonance sounding (MRS) is an electromagnetic method designed for groundwater investigations. MRS can be applied not only for studying fresh-water aquifers, but also in areas where intrusion of saline water is rendering the subsurface electrically conductive. In the presence of rocks with a high electrical-conductivity attenuation and a phase shift of the MRS signal may influence the efficiency of the MRS method. We investigated the performance of MRS for allowing us to propose a procedure for interpreting MRS data under these conditions. For numerical modeling, we considered a subsurface with a resistivity between 0.5 and 10 Ω m. The results show that the depth of investigation with MRS depends upon the electrical conductivity of groundwater and surrounding rocks, on the depth of the saline water layer, and on the amount of fresh water above the saline water. For interpreting MRS measurements, the electrical conductivity of the subsurface is routinely measured with an electrical or electromagnetic method. However, due to the equivalence problem, the result obtained with these methods may be not unique. Hence, we investigated the influence of the uncertainty in conductivity distribution provided by transient electromagnetic measurements (TEM) on MRS results. It was found that the uncertainty in TEM results has an insignificant effect on MRS.  相似文献   

Six intermediate-mass stars with far-infrared excess: a search for evolutionary connections     

Anatoly S. Miroshnichenko  Christopher L. Mulliss  Karen S. Bjorkman  Nancy D. Morrison  Kenesken S. Kuratov  John P. Wisniewski 《Monthly notices of the Royal Astronomical Society》1999,302(3):612-624

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An asymptotic approach to the inversion of free oscillation data     

Michael Brodski  Anatoly Levshin 《Geophysical Journal International》1979,58(3):631-654

Summary. A technique is suggested for the non-linearized inversion of subsets of free oscillation periods which are short enough that their asymptotic properties may be exploited. The general background of the method for monotonic and non-monotonic velocity distributions are described and applications to torsional and spheroidal free oscillation data are suggested. The advantages of joint analysis of travel times and free oscillation periods as a single data stream for non-linearized inversion are discussed.  相似文献   

Fission–track Ages and Magnetic Susceptibility of Cretaceous to Paleogene Volcanic Rocks in Southeastern Sikhote Alin, Far East Russia     

Takaaki MaTSUDA  Tohru SAKIYAMA  Ryo ENAMI  Yo–ichiro OTOFUJI  Vladimir G. SAKHNO  Anatoly P. MATUNIN  Ruslan G. KULINICH  Petr S. ZIMIN 《Resource Geology》1998,48(4):285-290

Abstract: Seven zircon fission-track ages and 30 magnetic susceptibilities were measured on welded pyroclastic rocks from the Bogopol and Sijanov Groups of the Cretaceous to Paleogene volcanic rocks in the southeastern part of the eastern Sikhote Alin volcano-plutonic belt, Far East Russia. The fission-track ages range from 42. 7 Ma to 64. O Ma which indicate that both the groups are of Early Paleogene time. Two thirds of the samples from the Bogopol Group have high magnetic susceptibility values, more than 3 A- 10^-3 SI unit, which imply that they are of the magnetite–series, whereas the samples from the Sijanov Group show 3 A- 10^-3 to 8 A- 10^-5 SI unit which suggest this group of probably the ilmenite-series.
The Paleogene age and high magnetic susceptibility of the Bogopol Group are quite similar to the Paleogene igneous rocks of the San'in belt, Southwest Japan. This suggests, taking accounts of the opening of the Japan Sea, that the eastern Sikhote Alin volcano-plutonic belt continued to the San'in Belt, and that the Paleogene igneous rocks along the Japan Sea coast of Northeast Japan were situated along the volcanic front of the eastern Sikhote Alin volcano-plutonic belt.  相似文献   

Sn, B and Pb-Zn Skarn, Vein and Disseminated Deposits in the East Sikhote–Alin, Russia     

Vladimir V. Ratkin  Anatoly N. Sokarev  Margarita D. Rysantseva 《Resource Geology》1998,48(1):7-11

Abstract: Sn, B and Pb-Zn skarn, vein and disseminated deposits occur in the eastern part of Sikhote-Alin fold system associated with the late Cretaceous-earliest Paleogene volcano-plutonic complexes, which are products of a continental margin-type subduction along the East Sikhote-Alin belt. There are two metallogenic zones where the ore deposits are concentrated. The Taukha metallogenic zone combining B and Pb-Zn skarn, vein and disseminated deposits occurs on the main volcanic chain along the Japan Sea coast. Late Cretaceous-earliest Paleogene calc-alkaline plutonic and volcanic rocks of magnetite series predominate here. Volcanic rocks overlie on the lower Cretaceous Taukha terrane which consists of abundant olistostromes with numerous olistoliths of Triassic limestones. During the middle-late Cretaceous time, an ignimbrite erupted and formed a huge borosilicate skarn deposit. A later subduction related volcanism of the late Cretaceous-earliest Paleogene stage (70–55 Ma) was predominated by andesites and rhyodacites. Many Pb-Zn skarn and vein deposits were formed. Sulfur isotope compositions of galena in the B and Pb-Zn deposits of the Taukha metallogenic zone vary from –1. 3 to +2. 0%, averaging 0% in the δ³⁴S.  相似文献