Cosmic microwave background anisotropy induced by a moving straight cosmic string

A method of searching for cosmic strings based on an analysis of the cosmic microwave background (CMB) anisotropy is presented. A moving straight cosmic string is shown to generate structures of enhanced and reduced brightness with a distinctive shape. The conditions under which a string can be detected by both CMB anisotropy and gravitational lensing in optical surveys are analyzed. For a relativistic string with a deficit angle of ～1″–2″, the amplitude of the generated anisotropy is shown to be ～15–30 μK.     

Kinky vortons

Cosmic vortons are closed loops of superconducting cosmic strings carrying current and charge. Despite a large number of studies the existence and stability of cosmic vorton solutions is still an open problem. Numerical simulations of the non-linear field theory are difficult to perform in (3+1)-dimensions, due to the existence of multiple length and time scales. In this paper we study a (2+1)-dimensional analogue of cosmic vortons, which we refer to as kinky vortons, where the cosmic string is replaced by a kink string. Many of the expected qualitative aspects of cosmic vortons transfer to kinky vortons, with the advantage that several approximations used in the study of cosmic vortons can be replaced by exact results. Furthermore, the numerical study of kinky vortons requires less computational resources than cosmic vortons, so a number of issues can be addressed in some depth. The radius of the kinky vorton is determined as a function of the charge and winding number, and it is shown that the chiral limit is a repulsive fixed point. Stability to both axial and non-axial perturbations is demonstrated in the electric and chiral regimes, though surpringly long lived ringing modes are observed. Kinky vortons which are too magnetic are shown to suffer from a pinching instability, which results in a reduction in the winding number and can convert magnetic into electric solutions.     

On the estimate of the energy of the nuclei of primary cosmic radiation generating extensive air showers

The analysis of the systematic errors in the determination of the energy of the particles of primary cosmic radiation that are inherent in the method for measuring extensive air showers (EASs) indicates the necessity of the exact inclusion of fragmentation in the nuclear interactions. The application of such a model developed for describing the experiments at the Relativistic Heavy Ion Collider improves the agreement between the energy spectra of the ultrahigh-energy cosmic rays measured at giant EAS arrays. It has been shown that the difference between the measured primary cosmic radiation flux intensities and the energies of the primary particles is within the methodical and instrumental errors. The real accuracy of the EAS method of studying ultrahigh-energy cosmic rays has been estimated using the data from six arrays.     

Variations in the optical and IR transparency of the Earth’s atmosphere under the action of cosmic rays and change in the thermodynamic parameters of the atmosphere

The effect of cosmic rays on the transparency of the Earth’s atmosphere and variations in its thermodynamic parameters is analyzed. Possible reasons for the change in the atmospheric transparency are considered. It is shown that variations in the transparency lead to a change in the temperature (and, therefore, pressure) distribution in the Earth’s atmosphere, as a result of which cosmic rays may affect the Earth’s climate.     

Thermodynamics and weak cosmic censorship conjecture of an AdS black hole with a monopole in the extended phase space

The first law of black hole thermodynamics has been shown to be valid in the extended phase space.However,the second law and the weak cosmic censorship conjecture have not been investigated extensively.We investigate the laws of thermodynamics and the weak cosmic censorship conjecture of an AdS black hole with a global monopole in the extended phase space in the case of charged particle absorption.It is shown that the first law of thermodynamics is valid,while the second law is violated for the extremal and near-extremal black holes.Moreover,we find that the weak cosmic censorship conjecture is valid only for the extremal black hole,and that it can be violated for the near-extremal black holes,which is different from the previous results.     

A natural way out of the conflict between cosmic strings and inflation

The phase transition which produces cosmic strings is studied in curved spacetime. It is shown that cosmic string formation naturally takes place in the late inflationary stage if the string-forming scalar field is appropriately coupled with the spacetime curvature. As a result the cosmic string scenario of galaxy formation turns out to be compatible with inflation.     

Self-force on an electric dipole in the spacetime of a cosmic string

We calculate the electrostatic self-force on an electric dipole in the spacetime generated by a static, thin, infinite and straight cosmic string. The electric dipole is held fixed in different configurations, namely, parallel, perpendicular to the cosmic string and oriented along the azimuthal direction around this topological defect, which is stretched along the z$z$ axis. We show that the self-force is equivalent to an interaction of the electric dipole with an effective dipole moment which depends on the linear mass density of the cosmic string and on the configuration. The plots of the self-forces as functions of the parameter which determines the angular deficit of the cosmic string are shown for those different configurations.     

Correlated variations of different cosmic ray components during thunderstorms and accompanying effects

The strong variations in cosmic rays observed by the Carpet air shower array at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) during thunderstorms are shown to have different origins. One type of event in particular is discussed: when disturbances in the intensities of the muon and electron-photon components of cosmic rays take place simultaneously. The correlations of these disturbances with variations in the geomagnetic field are presented and interpreted as a manifestation of a single physical process in the upper atmosphere. Details of this process are discussed.     

Paleoastrophysics: Progress and prospects

Results of highly accurate measurements of the radiocarbon concentration in the annual growth rings of trees over the last 400 years are presented. The temporal behavior of the intensity of galactic cosmic rays is reconstructed for the first time for the periods before, during, and after a deep and extended solar activity minimum — the Maunder minimum (1645–1715). It was established that even during the epoch of a deep solar minimum, the intensity of the galactic cosmic rays experienced solar modulation. The time profile of the generation of high-energy gamma radiation from the supernova explosion of 1006 is established. It is shown that processes of particle acceleration and generation of high-energy gamma rays take place with a three-year delay relative to the onset of the optical flare. The time profile of the generation of solar cosmic rays was obtained for the first time over the last thirty cycles of solar activity by precision measurements of the nitrate content in the polar ice cap. It is shown that solar flares accompanied by the generation of cosmic rays occur during the growth and decay phase of solar activity (measured by the Wolf numbers). Research prospects in the field of experimental paleoastrophysics are discussed. Zh. Tekh. Fiz. 69, 90–93 (September 1999)     

Cosmic muon flux at shallow depths underground

The cosmic muon background has been calculated for facilities placed at shallow depths. A relatively simple formula has been proposed for the muon spectrum at sea level that ensures the calculation of the depth dependences of the vertical muon intensity and integral muon flux. Calculations show that the zenith-angle distribution of the muon flux density is almost unchanged for depths from 10 to 100 m of solid rock. The muon angular distributions are presented for all three possible cases of the arrangement of the instruments in measurements carried out on the ground and at shallow depths. It has been shown that, to eliminate the cosmic muon background, it is necessary to install an active cosmic ray shielding “umbrella” covering a zenith angle ? of no less than 80°.     

The myth of cosmic symmetry breaking

General considerations are presented concerning symmetry and reference frames. It is shown that the Universe as a whole cannot possess perfect symmetry and that there was no cosmic symmetry breaking at cosmic phase transitions between cosmological eras. Cosmological schemes that assume perfect symmetry for the Universe are meaningless, but that can be circumvented. Assuming discontinuous evolution, high-energy physics does not reconstruct earlier eras. Specifically, any symmetry emerging at high energies cannot be a feature of earlier eras and is not a restoration of symmetry (that never was). The quantum era is considered and can reasonably be assumed to have been nontemporal, nonspatial, and extremely quantal. The Beginning can reasonably be identified with the quantum era or with the cosmic transition to space-time.On leave from the School of Physics and Astronomy, Tel-Aviv University, 69978 Tel-Aviv, Israel     

Cosmic rays and variations of the concentration of active nuclei of condensation and crystallization in the Earth’s atmosphere

A possible mechanism of the influence of cosmic rays on the concentration of neutral active nuclei of condensation and crystallization in the Earth’s atmosphere is considered. The mechanism is based on the variation in the transparency of the atmosphere under cosmic rays. It is shown that the concentration of active nuclei of condensation increase at low and middle altitudes, while the concentration of stable ice nuclei decreases. This effect and the change in the growth rate of drops can lead to correlation between the galactic cosmic rays and cloud cover anomalies at low altitudes and to the absence of correlation at middle altitudes. It is shown that the correlation between galactic cosmic rays and cloud cover anomalies can be absent at high altitudes.     

Cosmic sparks from superconducting strings

We investigate cosmic sparks from cusps on superconducting cosmic strings in light of the recently discovered millisecond radio burst by Lorimer et al.. We find that the observed duration, fluence, spectrum, and event rate can be reasonably explained by grand unification scale superconducting cosmic strings that carry currents approximately 10{5} GeV. The superconducting string model predicts an event rate that falls off only as S{-1/2}, where S is the energy flux, and hence predicts a population of very bright bursts. Other surveys, with different observational parameters, are shown to impose tight constraints on the superconducting string model.     

Ultrahigh energy cosmic rays,cosmological constant,and theta vacua

We propose that the origin of ultrahigh energy cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff and the origin of small cosmological constant can both be explained by vacuum tunneling effects in a theory with degenerate vacua and fermionic doublets. By considering the possibility of tunneling from a particular winding number state, accompanied by violation of some global quantum number of fermions, the small value of the vacuum dark energy and the production of high energy cosmic rays are shown to be related. We predict that the energy of such cosmic rays should be at least 5x10(14) GeV.     

First results of the CAKE experiment

We present the preliminary results of the cosmic abundances below the knee energies (CAKE) experiment for the study of the primary cosmic-ray composition and for the search of exotic particles in the primary cosmic radiation. CAKE uses CR39^® and Lexan nuclear track detectors, which were calibrated with beams of 158 AGeV Pb ions and 1 AGeV Fe ions at the CERN and BNL accelerators, respectively. Results based on the analysis of a first data sample are shown.     

Nonlinear propagation of cosmic rays in the galaxy

Propagation of cosmic rays in the interstellar medium after their emergence from sources—supernova remnants—may be accompanied by the development of flow instability which forms high magnetohydrodynamic turbulence and leads to nonlinear cosmic ray diffusion. A self-similar solution to the nonlinear diffusion equations is found and it is shown that the noted mechanism leads to an effective diffusion coefficient of cosmic rays, which coincides with the empirical value.     

Bianchi type-V string cosmological models in general relativity

Bianchi type-V string cosmological models in general relativity are investigated. To get the exact solution of Einstein’s field equations, we have taken some scale transformations used by Camci et al [Astrophys. Space Sci. 275, 391 (2001)]. It is shown that Einstein’s field equations are solvable for any arbitrary cosmic scale function. Solutions for particular forms of cosmic scale functions are also obtained. Some physical and geometrical aspects of the models are discussed.     

Temporal changes in the energy spectrum of Forbush decreases in 20–23 solar activity cycles

Variations in the energy spectrum of galactic cosmic rays during Forbush decreases registered in the 20–23 solar activity cycles are studied, using the data from neutron monitors and the Yakutsk cosmic ray spectrograph. It is shown that the Forbush decreases in the 23rd cycle of solar activity had a harder energy spectrum than in the three previous cycles, due to the relatively low level of turbulence of the interplanetary magnetic field during the 23rd solar activity cycle.     

Influence of the finiteness of particle velocity on the energy spectrum of cosmic rays in an anomalous diffusion model with Lévy flights

An estimate of the influence the finiteness of particle velocity has on the results of a fractional differential (anomalous) model of cosmic ray propagation in the Galaxy with Lévy flights developed by the authors is considered. The results from Monte Carlo simulations of particle diffusion in random walk models with finite and infinite velocities are presented. It is shown that considering particle velocity finiteness has almost no effect on the cosmic ray energy spectrum obtained for E > 1 GeV in the anomalous diffusion model with Lévy flights for nearby young sources.     

Ultimate energy of cosmic rays generated in supernova shells

It is shown that the ultimate energy of cosmic rays accelerated in a supernova shell due to the surfing acceleration mechanism is determined by the shell radius and the interstellar magnetic field. The ultimate energy of cosmic rays accelerated in the supernova shock does not exceed 10¹⁷ eV for typical values of the interstellar magnetic field in the vicinity of a supernova and the radii of observed supernova shells.