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1.
We present models, in which phantom energy interacts with two different types of dark energies including variable modified Chaplygin gas (VMCG) and new modified Chaplygin gas (NMCG). We then construct potentials for these cases. It has been shown that the potential of the phantom field decreases from a higher value with the evolution of the Universe.  相似文献   

2.
Shortly the vacuum component of the Universe from the geometry point of view and from the point of view of the standard model of physics of elementary particles is discussed. Some arguments are given to the calculated value of the cosmological constant (Zel’dovich’s approximation). A new component of space vacuum (the gravitational vacuum condensate) is involved the production of which has fixed time in our Universe. Also the phenomenon of vacuum selforganization must be included in physical consideration of the Universe evolution.  相似文献   

3.
A special class of type Ia supernovae that is not subject to ordinary and additional intragalactic gray absorption and chemical evolution has been identified. Analysis of the Hubble diagrams constructed for these supernovae confirms the accelerated expansion of the Universe irrespective of the chemical evolution and possible gray absorption in galaxies.  相似文献   

4.
《New Astronomy Reviews》2007,51(7):539-546
Cosmological gamma ray bursts (GRBs) are the brightest explosions in the Universe. Satellite detectors, such as Beppo-SAX, HETE2 and more recently Swift, have provided a wealth of data, including the localization and redshifts of subsets of GRBs. The redshift distribution has been utilized in several studies in attempts to constrain the evolving star formation rate and to probe GRB rate evolution in the high-redshift Universe. These studies find that the GRB luminosity function and/or the rate density evolve with redshift. We present a short review of the problems of constraining GRB rate evolution in the context of the complex mix of biases inherent in the redshift measurements. To disentangle GRB rate evolution from the biases prevalent in the redshift distribution will require accounting for the incompleteness of the observed redshift sample. We highlight the importance of formulating a ‘complete GRB selection function’ to account for the main sources of bias.  相似文献   

5.
The motion of one point mass of the classical mechanics is treated by means of the relativistic spinor regularization (KUSTAANHEIMO 1975). Most general spinor equations of motion (2.9)‒(2.10)and the differential equations(3.16)‒(3.25)for the “possible integrals” (3.2)‒(3.11)of these quations of motion are deduced. If the force is a superposition of a conservative central force and of another force perpendicular to radius vector and velocity (Chapter 4, Case D), then the theory yields scalar and spinor integrals (4.7), (4.10)‒(4.12), (4.14)‒(4.15), (4.17), (4.28) that enable a parametric representation of the orbit by quadratures, as soon as one solution of a RICCATI differential equation (4.33) has been found.  相似文献   

6.
It is shown that the singularity of space-time in Einstein-Friedmann's cosmology can be avoided, if one takes into account the strong interaction of the elementary particles in the earliest stage of the Universe. Under the additional assumption that there exists a maximum temperature of particles and radiation (T max?1.9×1012 K) in consequence of which the number of hadrons (nucleons) in the early Universe has been greater than today by a factor of about 107, the Friedmann equation is integrated numerically where the integration constant is fitted by the present values of the massdensity, the Hubble-constant and the temperature of the background radiation. The minimum radius of curvature of the Universe becomes 1.4×1011 km; the density in its neighbourhood remains within reasonable limits of the magnitude of the nuclear density. The early evolution of the Universe with time will be discussed in detail. Concerning the idea of an universal upper limit for the temperature we follow the considerations of Hagedorn, but in contrast to the existing investigations we take explicitly into account the negative potential energy of the strong interaction according to Yukawa's theory.  相似文献   

7.
We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy given by a cosmological constant. The perfect fluid is chosen to be the one obeying either the usual equation of state, i.e., p = ζ, with ζ ∊ [0, 1] or a van der Waals equation of state. Role of the Λ term in the evolution of the BI Universe has been studied.  相似文献   

8.
We use the results of the SCUBA Local Universe Galaxy Survey, a submillimetre (submm) survey of galaxies in the nearby Universe, to investigate the relationship between the far-infrared (FIR)–submm and radio emission of galaxies at both low and high redshift. At low redshift we show that the correlation between radio and FIR emission is much stronger than the correlation between radio and submm emission, which is evidence that massive stars are the source of both the FIR and radio emission. At high redshift we show that the submm sources detected by SCUBA are brighter sources of radio emission than are predicted from the properties of galaxies in the local Universe. We discuss possible reasons for the cosmic evolution of the relationship between radio and FIR emission.  相似文献   

9.
夏子晴 《天文学报》2021,62(2):21-112
目前已经有很多观测证据表明宇宙中存在着大量暗物质,其能量密度占据了目前宇宙总能量密度的1/4.根据高精度的数值模拟和引力透镜观测,我们已经对从矮星系到星系团中的暗物质空间分布有了较好的理解,但是对于暗物质究竟是什么我们还一无所知.由此,物理学家提出了很多假想的粒子模型.  相似文献   

10.
Information in the universe evolves according to a nonlinear law, which results from a combination of nonlinear dynamics and quantum theory. The Kolmogoroff-Sinai entropy rate of the Universe evolves in inverse proportion to the temperature. Since the evolution of temperature is known from standard cosmology, the time dependence of the universal entropy rate can be determined and the temporal evolution of the universal information content can be calculated. Information starts growing at the enormous rate of 1044 bits per second from an initial value of at least 2 (seven) bits at Planck time. However, it reaches its contemporary value only if one or more inflationary phases have been passed by the Universe in the course of its evolution.  相似文献   

11.
F-essence is a generalization of the usual Dirac model with the nonstandard kinetic term. In this paper, we introduce a new model of spinor cosmology containing both Ricci scalar and the non minimally coupled spinor fields in its action. We have investigated the cosmology with both isotropy and anisotropy, where the equations of motion of FRW and Bianchi type-I spacetimes have been derived and solved numerically. Finally the quantization of these models through Wheeler-De Witt (WD) wave function has been discussed.  相似文献   

12.
We discuss a mechanism for producing baryon density perturbations during the inflationary stage, and study the evolution of the baryon charge density distribution in the framework of the low-temperature baryogenesis scenario. This mechanism may be important for large-scale structure formation in the Universe and, in particular, may be essential for understanding the existence of a characteristic scale of 130  h −1 Mpc (comoving size) in the distribution of the visible matter.
A detailed analysis shows that both the observed very large scale of the visible matter distribution in the Universe and the observed baryon asymmetry value could naturally appear as a result of the evolution of a complex scalar field condensate, formed at the inflationary stage.
Moreover, according to our model, the visible part of the Universe at present may consist of baryonic and antibaryonic regions, sufficiently separated, so that annihilation radiation is not observed.  相似文献   

13.
《New Astronomy Reviews》1999,43(2-4):223-241
In this paper, we present the evolution of primordial chemistry. We describe the period in the expansion of the Universe referred to as the epoch of recombination, then the evolution of the Universe during the gravitational collapse of protoclouds.  相似文献   

14.
The maximal entropy and the final parameters of the expansive-creative evolution phase of the ultrastable Universe can be determined from model properties of the expansive nondecelerative Universe.The possibility of existence of primordial black holes with temperature of the Universe follows from the initial entropy of the Universe. This fact throws new light on the problem of dark matter.  相似文献   

15.
From the analysis of relativistic and quantum-mechanical processes at the creation of the expansive evolution phase of the Universe it follows that the Universe can expand only by the limit velocity of signal propagationc.  相似文献   

16.
通过搜集了457个活动星系核样本,根据活动星系核的演化实质是指宇宙时标上的变化,讨论了红移量与活动星系核演化的关系,最终证明了活动星系核的演化分为两个序列:(1)从类星体到Seyfert星系之间的演化;(2)平谱射电类星体(FSRQ)—BL Lac天体—射电星系(RG)的演化。  相似文献   

17.
A cosmological model is discussed which is based on interpretation of the red shift by decrease of the light speed with time everywhere in the Universe beginning with a certain moment of time in the past. The model is described by a metric in which the light speed depends on time and the radius of the curvature of three-dimensional space remains constant (c-metric). It is shown that this metric leads to the same observed facts and formulas of different characteristics that the metric of standard cosmology does but with essentially different physical interpretation. Such a property is the consequence of conformity of spaces being defined by both metrics. The agreement with the fundamental physics laws is achieved by introducing the evolution of a number of other fundamental constants synchronously with the variation of the light speed. The model considered connected the evolution of the Universe with evolution of physical constants and permits explaining some unclear cosmological phenomena — for example, a high isotropy of the relict background and superluminal speed in quasars.  相似文献   

18.
Neutron stars are the densest objects known in the Universe. Being the final product of stellar evolution, their internal composition and structure is rather poorly constrained by measurements.  相似文献   

19.
In this letter, we have assumed that the Universe is filled in tachyonic field with potential, which gives the acceleration of the Universe. For certain choice of potential, we have found the exact solutions of the field equations. We have shown the decaying nature of potential. From recently developed statefinder parameters, we have investigated the role of tachyonic field in different stages of the evolution of the Universe.  相似文献   

20.
It has been suggested that the highest-energy cosmic rays might be protons resulting from collapsing cosmic strings in the Universe. We point out that this mechanism, although attractive, has important shortcomings, notably the fact that gamma rays produced along with the protons and those produced by the protons in their interactions with the cosmic background radiation generate cascades in the Universe and result in unacceptably high fluxes of cosmic gamma rays in the region of hundreds of MeV.  相似文献   

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