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1.
A modification of the Press-Schechter model for the mass function of the dark halos, whose population develops in the presence of a supercluster or a cosmological void, is proposed. The large-scale structure is specified as a set of statistical constraints in the form of linear functionals that are applied to the initial overdensity field. The parameters and values of these functionals are related to properties of the large-scale structure: its mean density, spatial scales, and shape. The model is applied to the simple case of a spherically symmetric background structure to demonstrate a procedure for recovering these parameters by fitting the halo mass function.  相似文献   

2.
We briefly discuss a modern view of the cosmological constant. It is suggested that the cosmological constant was “hardened” at E ~ 150 MeV after the latest (quark-gluon) phase transition. Until this energy was reached, the vacuum component of the Universe evolved (decreased) in a series of discontinuous jumps; i.e., condensates of quantum fields made negative contributions to its positive energy density. This was the quintessence period of the evolution of the Universe, when it underwent an intense loss of symmetry during the first fractions of a microsecond of its existence. However, this point of view is not without criticism, and other approaches are considered. In particular, the small value of the cosmological constant and its ability to accelerate the expansion of the Universe is of great interest. Although all available data on the cosmological constant were recently summarized and classified by S. Nobbenhuis, no satisfactory solution to this problemhas been reached, and this represents a major difficulty for progress in quantum-gravity theory and cosmology. We briefly discuss the possibility for stars to be formed from dark energy (vacuum stars) and the extension of holographic ideas to the entire Universe. We also consider the possibility of solving the problem of the cosmological constant by introducing a universal wave function; i.e., quantum decoherence, which implies the rejection of the Copenhagen interpretation of quantum mechanics and the acceptance of H. Everett’s point of view.  相似文献   

3.
The evolution of the vacuum component of the Universe is studied in both the quantum and classical regimes. Our Universe has emerged as a result of a tunneling process, beginning with an oscillating mode and passing on to a Friedmann mode, and it very probably had a high symmetry for the Planck parameters. In the first fractions of a second (the quantum regime), as it cooled, the vacuum component of the Universe lost its high degree of symmetry due to phase transitions; i.e., its positive energy density was subject to negative contributions from quantum field condensates (by 78 orders of magnitude). After the last (quark-hadron) phase transition, the vacuum energy ??froze.?? At this time (10?6 s), the vacuum energy density can be calculated using the formula of Zel??dovich and substituting the mean values of the pseudo-Goldstone boson (??-mesons) masses characterizing the chromodynamic vacuum. Chiral symmetrywas lost at that time. The dynamics of the equilibrium vacuum after its ??hardening?? is considered using the holographic principle. During the next 4 × 1017 s (the classical regime), the vacuum component of the Universe was reduced by 45 orders of magnitude due to the creation of new quantum states during its expansion. It is possible to solve the cosmological-constant problem using the holographic principle, since the 123 problematic orders of magnitude disappear in usual physical processes. The vacuum energy density is also calculated in the classical regime to a redshift of 1011 using a ??cosmological calculator.??  相似文献   

4.
The positions of star-forming complexes (SFCs) in color-luminosity, color-color, and chemical composition-luminosity diagrams are determined by the star-formation regime (history). Taking into account the fraction of Lyman continuum photons that are not absorbed by hydrogen, we find a strong correlation between the observed color indices and the total Lyman continuum flux from the stars in SFCs. The distribution of extragalactic SFCs in a plot of the slope of the initial mass function (IMF) versus the density of stars cannot be distinguished from this distribution for clusters in the Galaxy and the Large Magellanic Cloud, where the IMF slopes were derived directly from star counts.  相似文献   

5.
A step-by-step foundation for the differential character of the Universe’s rotation is presented. First, invoking the concept of spacetime foam with spin, it is reasonable to assume that the very early Universe can be described by the Dirac equation. Second, it is shown using the Ehrenfest theorem that, from a classical point of view, the early Universe can be described by the Papapetrou equations. Third, it is stressed that our Universe can perform only rotational motion. It is shown based on the spin part of the Papapetrou equations that the Universe’s rotation depends appreciably on the physical properties of a specific cosmological epoch. The rotational angular velocity is calculated for three basic cosmological epochs: the matter-dominated epoch, the transition period (from domination of matter to domination of vacuum), and the vacuum-dominated epoch.  相似文献   

6.
Bolometric light curves for the afterglow resulting from the passage of a gamma-ray burst through a molecular cloud are computed. The profile and duration of the afterglow light curve depend strongly on the distribution of matter in the cloud, the degree of collimation of the gamma-ray radiation, and the observing conditions. The peak can be reached as soon as seven days (the gamma-ray burst is located at some distance from the center of a molecular cloud with small-scale density enhancements), or as long as one to three years (the gamma-ray burst is located at the center of a uniform molecular cloud) after the burst. The bolometric luminosity of the re-radiated signal can reach 6.5 × 1042 erg/s.  相似文献   

7.
The balance equations for the quasi-stationary recombination of hydrogen plasma in a black-body radiation field are solved. The deviations of the excited level populations from equilibrium are computed and the rates of uncompensated line transitions determined. The expressions obtained are stable for computations of arbitrarily small deviations from equilibrium. The average number of photons emitted in hydrogen lines per irreversible recombination is computed for plasma parameters corresponding to the epoch of cosmological recombination.  相似文献   

8.
Historical aspects of sky surveys carried out on the RATAN-600 radio telescope and studies of radio sources and background radiation detected in these surveys are considered.  相似文献   

9.
峨眉山玄武岩的岩相与岩体结构   总被引:16,自引:0,他引:16  
峨眉山玄武岩是西南地区水电工程的主要建基岩体,其岩体结构明显受其建造的控制,不同地区,不同岩相的玄武岩,由于岩石组合及原生结构特征等的差异,而具有不同的岩体结构特征。本文结合拟建金沙江溪洛渡水电工程,雅砻江官地水电工程等实例,从岩相角度分析了玄武岩岩相及原生结构及原生结构对其岩体结构的控制作用。  相似文献   

10.
The conditions for the fragmentation of the baryonic component during mergers of dark matter halos in the early Universe are studied. We assume that the baryonic component undergoes a shock compression. The characteristic masses of protostellar molecular clouds and the minimum masses of protostars originating in these clouds decrease with increasing halo mass. This may indicate that the initial stellar mass function in more massive galaxies was shifted towards lower masses during the initial stages of their formation. This would result in an increase in the number of stars per unit mass of the halo, i.e., in an increase in the efficiency of star formation.  相似文献   

11.
A method for using the colors of star-forming complexes to derive the slope and upper mass limit of the initial mass function (IMF) and the age of the complex is proposed in the framework of synthetic evolutionary models of star-cluster populations. The star-formation parameters of 105 complexes in 20 spiral and irregular galaxies are determined. The IMF slopes in different star-forming complexes differ appreciably, and their dependence on the luminosities and masses of the complexes is derived. The duration of the star-formation period increases with the luminosity of the complex, and complexes with longer star-formation periods are richer in metals. The slope of the integrated IMF in a Galaxy depends on the mass spectrum of its complexes, and the upper mass limit of the IMF is lower in early-type spirals.  相似文献   

12.
地质标准物质的最小取样量问题   总被引:8,自引:1,他引:8  
地质标准物质已是当今地质分析数据质量保证与监控系统中最重要的手段之一。正确使用标准物质的重要条件是遵循标准物质最小取样量的规定。然而当今高灵敏度、小取样量(20-30mg)的现代主流分析技术正向着当前普遍使用的地质标准物质100mg最小取样量的要求提出挑战。本文从历史演变和当前需求讨论了地质分析取样量问题以及地质标准物质最小取样量及其应用意义,并提出了解决当前这一矛盾的技术措施与步骤。同时也提醒分析方法研究者、质量管理者和标准物质研制者关注取样量问题,以使更新换代快的技术方法和相对滞后的监管方法(包括标准物质)得到协调发展。  相似文献   

13.
地质标准物质已是当今地质分析数据质量保证与监控系统中最重要的手段之一。正确使用标准物质的重要条件是遵循标准物质最小取样量的规定。然而当今高灵敏度、小取样量(20-30mg)的现代主流分析技术正向着当前普遍使用的地质标准物质100mg最小取样量的要求提出挑战。本文从历史演变和当前需求讨论了地质分析取样量问题以及地质标准物质最小取样量及其应用意义,并提出了解决当前这一矛盾的技术措施与步骤。同时也提醒分析方法研究者、质量管理者和标准物质研制者关注取样量问题,以使更新换代快的技术方法和相对滞后的监管方法(包括标准物质)得到协调发展。  相似文献   

14.
Pointwise division in the Fourier domain can be used to deconvolve the effects of aircraft altitude upon gridded, two-dimensional, radiometric count data. The appropriate divisor function, expressed as a triple integral by Gunn, is developed as a convergent series suitable for its numerical evaluation. For various flying heights, graphs display in cross-section the corresponding, radially symmetric, divisor function.  相似文献   

15.
Data on the dependences of the masses and bolometric luminosities of Active Galactic Nuclei on their cosmological redshifts are used to determine the redshift dependences of their X-ray luminosities and the kinetic powers of their relativistic jets. These results are used, in turn, to obtain the redshift dependence of the spins of the central supermassive black holes.  相似文献   

16.
裂隙岩体独特的裂隙网络结构,控制了其内在的各种力学及水力学行为。因而对裂隙岩体网络结构特征的研究,成为对裂隙岩体水力学特性研究的基础。文章结合石太客运专线特长隧道(太行山隧道)分析了隧道区裂隙发育特征及地质构造对渗透性的影响,量化裂隙岩体结构特征,为准确地预测隧道涌、突水位置及水量提供了理论的依据。  相似文献   

17.
The rapid development of biomarker geochemistry and its application to petroleum exploration problems has been due in no small part to gas chromatography-mass spectrometry (GC-MS). The recent availability of hybrid and triple stage quadrupole mass spectrometers have introduced a number of novel ways for the detection and identification of biomarkers present in extremely complex mixtures of organic compounds from various sources including crude oils and source rock extracts.A triple stage quadrupole mass spectrometer has been used in the MS/MS mode with both a gas chromatograph and direct insertion probe as inlet systems, to develop alternative methods for biomarker analyses. Selected ions formed in the ion source of the mass spectrometer are permitted to enter the collision cell where, following collision with an inert gas, the daughter ions are separated using the third quadrupole. In this manner specific parent/daughter ion relationships are utilized to monitor and resolve classes of biomarkers or individual components from within a complex mixture. Furthermore, deuterated analogues of naturally occurring biomarkers can be utilized for quantitation purposes since the parent/daughter relationship for the standard will differ, depending on the number of deuterium atoms present, even though the relative retention times are identical.The ability of MS/MS to resolve components spectrometrically as well as chromatographically greatly enhances the analytical short-column capabilities of this system. In this paper the utilization of GC-MS/MS and the direct insertion probe MS/MS to determine biomarker distributions in crude oils both qualitatively and quantitatively are discussed. The results from the study show that it is possible to use the probe data to rapidly correlate oils on the basis of their source materials and if necessary select samples for more detailed analysis by GC-MS/MS. A major advantage of the direct insertion probe method is speed of analysis although some component resolution is lost. In an effort to minimize this problem and still maintain the rapid analysis time, the use of short columns in the GC is also described. This approach provides the ability to undertake relatively rapid analyses with limited chromatographic resolution but at relatively high levels of sensitivity.  相似文献   

18.
19.
测量地应力的新方法   总被引:6,自引:3,他引:6  
周小平  王建华 《岩土力学》2002,23(3):316-320
论述了用赤平投影学方法分析确定地应力的主方向,用Kaiser效应测量地应力大小。将两者有机结合起来可以克服Kaiser效应测量地应力时,主应力方向难以确定的最大缺点。通过和传统现场地应力测量方法比较,表明该法具有更为简单,更为经济,准确度高等优点,便于大量测量,以寻求工程地区地应力变化规律。  相似文献   

20.
H. Sauer 《GeoJournal》1977,1(3):41-54
Summary To sum up it can be said that new or further developed systems of haulage must be found, especially in conurbations, in order to be able to cope efficiently with freight transport. The scheme here presented for freight distribution centres is one possibility which has been much discussed. The establishment of such a freight distribution centre in Koblenz by the end of 1976 could be regarded as a first step towards its realization. By means of this model which was generally planned by Dornier and which is open to visit, provides solutions for many problems. It is yet too early for a final evaluation of the entire system but approaches have been made to the Federal Ministry of Research and Technology for a research project and thus to a good starting point for realization.  相似文献   

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