A possible mechanism for the injection of particles into a cosmic ray acceleration region

The composition of the nucleonic component of the primary cosmic radiation has been compared with the natural abundance of the elements. A normalized quotient between the abundance of an element in the radiation and in nature was found to be approximately equal toZ , whereZ is the atomic number and is a constant approximately equal to one. The observed excess of the heavy elements can be expected in the radiation if the selection of the cosmic ray particles is performed by ionization through fast electron or proton impacts on neutral matter having normal composition. Such a selection mechanism may act in regions in space where fast moving thin plasma clouds collide with clouds of neutral matter. A source model in which the plasma clouds originate in Type II supernova explosions is discussed.     

Major and trace element geochemistry of S‐type cosmic spherules

Micrometeorites that pass through the Earth's atmosphere undergo changes in their chemical compositions, thereby making it difficult to understand if they are sourced from the matrix, chondrules, or calcium–aluminum‐rich inclusions (CAIs). These components have the potential to provide evidence toward the understanding of the early solar nebular evolution. The variations in the major element and trace element compositions of 155 different type (scoriaceous, relict bearing, porphyritic, barred, cryptocrystalline, and glass) of S‐type cosmic spherules are investigated with the intent to decipher the parent sources using electron microprobe and laser ablation inductively coupled plasma‐mass spectrometry. The S‐type cosmic spherules appear to show a systematic depletion in volatile element contents, but have preserved their refractory trace elements. The trends in their chemical compositions suggest that the S‐type spherules comprise of components from similar parent bodies, that is, carbonaceous chondrites. Large fosteritic relict grains observed in this investigation appear to be related to the fragments of chondrules from carbonaceous chondrites. Furthermore, four spherules (two of these spherules enclose spinels and one comprised entirely of a Ca‐Al‐rich plagioclase) show enhanced trace element enrichment patterns that are drastically different from all the other 151 cosmic spherules. The information on the chemical composition and rare earth elements (REEs) on cosmic spherules suggest that the partially to fully melted ones can preserve evidences related to their parent bodies. The Ce, Eu, and Tm anomalies found in the cosmic spherules have similar behavior as that of chondrites. Distinct correlations observed between different REEs and types of cosmic spherules reflect the inherited properties of the precursors.     

Periodic variations of the cosmic radiation—III. The 27-day variation

The relation between the 27-day variation of the cosmic radiation and of the terrestrial horizontal magnetic intensity has been investigated by means of the data recorded from 1957 to 1968. The periods have a correlation of about +0.5. The cosmic radiation is undoubtedly modulated by the Sun. A persistent wave with a periodicity of approximately 27.2 days could be proved from the data of several ion chamber and neutron monitor stations, but not underground (14m w.e.). The frequency of the daily period of the cosmic radiation shows a 27.3 day variation, too. The sum total of the relative sunspot numbers has a period length of 27.4 days. Their connection with the cosmic radiation is discussed.     

A Moon orbiting observatory for the measurement of the elemental and isotopic composition in the primary cosmic radiation

We describe a project for the measurement of elemental composition of the primary cosmic radiation to be performed by a space observatory orbiting around the Moon. The absence of atmosphere and the low intrinsic magnetic field of the Moon give access to the very low energy component of the cosmic radiation, allowing the search for rare events.The quest for antinuclei, the determination of the lunar lepton albedo and the abundance measurement of galactic radioactive clocks (Be¹⁰, C¹⁴, Al²⁶) are the major tasks of the ANTARES apparatus (ANTimatter Assessment RESearch).We report details of the instrument design, the expected performance for single detectors, their capability to accomplish the proposed measurements and the characteristics of the space mission.     

Energy Composition of the Universe: Time-Independent Internal Symmetry

The energy composition of the Universe, as emerged from the Type Ia supernova observations and the WMAP data, looks preposterously complex, – but only at the first glance. In fact, its structure proves to be simple and regular. An analysis in terms of the Friedmann integral enables to recognize a remarkably simple time-independent covariant robust recipe of the cosmic mix: the numerical values of the Friedmann integral for vacuum, dark matter, baryons and radiation are approximately identical. The identity may be treated as a symmetry relation that unifies cosmic energies into a regular set, a quartet, with the Friedmann integral as its common genuine time-independent physical parameter. Such cosmic internal (non-geometrical) symmetry exists whenever cosmic energies themselves exist in nature. It is most natural for a finite Universe suggested by the WMAP data. A link to fundamental theory may be found under the assumption about a special significance of the electroweak energy scale in both particle physics and cosmology. A freeze-out model developed on this basis demonstrates that the physical nature of new symmetry might be due to the interplay between electroweak physics and gravity at the cosmic age of a few picoseconds. The big ‘hierarchy number’ of particle physics represents the interplay in the model. This number quantifies the Friedmann integral and gives also a measure to some other basic cosmological figures and phenomena associated with new symmetry. In this way, cosmic internal symmetry provides a common ground for better understanding of old and recent problems that otherwise seem unrelated; the coincidence of the observed cosmic densities, the flatness of the co-moving space, the initial perturbations and their amplitude, the cosmic entropy are among them.     

Detection of atmospheric Cherenkov radiation using solar heliostat mirrors

There is considerable interest world-wide in developing large area atmospheric Cherenkov detectors for ground-based gamma-ray astronomy. This interest stems, in large part, from the fact that the gamma-ray energy region between 20 and 250 GeV is unexplored by any experiment. Atmospheric Cherenkov detectors offer a possible way to explore this region, but large photon collection areas are needed to achieve low energy thresholds. We are developing an experiment using the heliostat mirrors of a solar power plant as the primary collecting element. As part of this development, we built a detector using four heliostat mirrors, a secondary Fresnel lens, and a fast photon detection system. In November 1994, we used this detector to record atmospheric Cherenkov radiation produced by cosmic ray particles showering in the atmosphere. The detected rate of cosmic ray events was consistent with an energy threshold near 1 TeV. The data presented here represent the first detection of atmospheric Cherenkov radiation using solar heliostats viewed from a central tower.     

Pulsed galactic nuclei and the origin of cosmic rays

The possibility that a series of explosions of the galactic nuclei every 5×10⁶ yr can cause a substantial flux of cosmic ray particles at the vicinity of the Earth is investigated. The steady flux of cosmic radiation forces the conclusion that there have been explosions back to 10⁹ yr if this is a dominant source of cosmic rays.     

Thermodynamics and two-fluid cosmological models

Exact solutions of Einstein's field equations and the laws of thermodynamics are presented in which both a comoving radiative perfect fluid (modelling the cosmic microwave background) and a non-comoving imperfect fluid (modelling the observed material content of the Universe) act as the source of the gravitational field as represented by the flat FRW line element. The tilting velocity of the imperfect fluid is associated with the peculiar velocity of our local cluster of galaxies relative to the cosmic microwave background. In these relativistic two-fluid cosmological models the temperatures of the radiation and matter fields are equal until hydrogen recombines at 4000 K, after which time thermal contact between the two fluids is broken. The models presented are physically acceptable cosmologies that are shown to give rise to numerical predictions consistent with current observations.     

The fragmentation of cosmic-ray nuclei in interstellar hydrogen

In order to calculate the effects of traversal of interstellar matter on the charge spectrum of the cosmic radiation it is necessary to have values for the fragmentation parameters of nuclei of each element into all lighter elements. Most of these values have not been experimentally determined. As a consequence, they have been calculated from a semi-empirical mass spallation relation designed to fit the available partial cross-sections obtained from radio chemical determinations. This calculation has attempted to take into account the conditions that are peculiar to the cosmic ray problem. Values of the parameters are given for three characteristic energies and a comparison is made with the sparce experimental data. The effects of using these parameters in a calculation of the extrapolation of the charge spectrum through interstellar space are shown for some representative cases.This work was supported by the U.S. Office of Naval Research under Contract No. Nonr 710-60.     

The radiation features of the moving charges and the effects suppressed by the cosmic plasmas in pulsars and other celestial bodies

In this paper, we have discussed the feature of radiation resulting from the moving magnetic charges in detail. We have pointed out that there is the curvature radiation of the monopoles in pulsars and other celestial bodies, but this radiation can intensely be suppressed by the cosmic plasma.     

Modified theory of gravity and the history of cosmic evolution

A continuous transition from early Friedmann-like radiation era through to late time cosmic acceleration passing through a long Friedmann-like matter dominated era followed by a second phase of radiation era has been realized in modified theory of gravity containing a combination of curvature squared term, a linear term, a three-half term and an ideal fluid. Thus the history of cosmic evolution is explained by modified theory of gravity singlehandedly. The second phase of radiation-like era might provide an explanation to the hydrogen and helium reionization at low redshift.     

Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors

The mass composition of high-energy cosmic rays at energies above 10¹⁵ eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass lnA by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the “knee” region is robust against a variety of systematic effects.     

A general upper limit on the mass and entropy production of a cluster of supermassive objects

The recent discovery of a distortion in the 3K spectrum of the black-body background cosmic radiation has led to suggestions that a part or even all of the radiation was generated by pregalactic supermassive stars. A general upper limit on the mass of a cluster of these objects and the entropy of the radiation produced by them is obtained.     

Cosmic ray composition and energy spectrum from 1–30 PeV using the 40-string configuration of IceTop and IceCube

The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above ∼1 TeV using the IceCube array. This unique detector arrangement provides an opportunity for precision measurements of the cosmic ray energy spectrum and composition in the region of the knee and beyond. We present the results of a neural network analysis technique to study the cosmic ray composition and the energy spectrum from 1 PeV to 30 PeV using data recorded using the 40-string/40-station configuration of the IceCube Neutrino Observatory.     

A MC approach to simulate up- and down-going neutrino showers including local topographic conditions

The extragalactic flux of protons is predicted to be suppressed above the famous Greisen–Zatsepin–Kuzmin cut-off at about E_GZK  50 EeV due to the resonant photo-pion production with the cosmic microwave background. Current cosmic ray data do not give a conclusive confirmation of the GZK cut-off and the quest about the origin and the chemical composition of the highest energy cosmic rays is still open. Amongst other particles neutrinos are expected to add to the composition of the cosmic radiation at highest energies. We present an approach to simulate neutrino induced air showers by a full Monte Carlo simulation chain. Starting with neutrinos at the top of the atmosphere, the performed simulations take into account the details of the neutrino propagation inside the Earth and atmosphere as well as inside the surrounding mountains. The products of the interactions are input for air shower simulations. The mountains are modelled by means of a digital elevation map. To exemplify the potential and features of the developed tools we study the possibility to detect neutrino induced extensive air showers with the fluorescence detector set-up of the Pierre Auger Observatory. Both, down-going neutrinos and up-going neutrinos are simulated and their rates are determined. To evaluate the sensitivity, as a function of the incoming direction, the aperture, the acceptance and the total observable event rates are calculated for the Waxman–Bahcall (WB) bound.     

Anisotropic expansion of the universe and the anisotropy and linear polarisation of the cosmic microwave background

The relativistic transfer equation for polarised radiation is solved in an axisymmetric Bianchi type I universe. Previous results concerning the linear polarisation induced in the cosmic microwave background radiation by Thomson scattering in an anisotropically expanding universe are confirmed. Work partly done at the Osservatorio Astrofisico, Catania (Italia).     

Studies of the correlation between the global radiation,ultraviolet radiation,cosmic radiation,sunspot number and meteorological parameters

The correlation between the ratio of the global irradiation to the extraterrestrial solar radiation (H/H ₀), and the ratio of the ultraviolet solar irradiation to the extraterrestrial solar radiation (H _u /H ₀) on a horizontal surface at Bahrain (=26°), and some terrestrial and solar parameters (the monthly average relative humidity, temperature, relative sunshine duration, cosmic radiation intensity, and sunspot number) have been studied. Moreover, the role of the solar effects and the terrestrial effects on the global and the solar ultraviolet radiation has been studied. A detailed investigation has been carried between the level of the cosmic radiation received at Bahrain and the sunspot number. It was concluded that as the solar activity increases, cosmic radiation and sunspot number play a predominant effect on the correlation of (H/H ₀) and (H _u /H ₀). Furthermore, the correlation between cosmic radiation and sunspot number also increases.     

The Sunyaev-Zel'dovich effect in the millimetric region

We analyse the spectral shape and possible spurious distortions of the Sunyaev-Zel'dovich effect, arising from the interaction of the cosmic background radiation with hot gases of rich clusters, in the millimetric region. We show that one can measure this effect with high accuracy with present-day infrared detectors, obtaining a larger amount of information than by using radio systems. In particular, one can accurately measure the temperature of the cosmic background radiation without the usual absolute calibration of the detector.     

Formation of E chondrites and aubrites—A thermodynamic model

Condensation and accretion models for the formation of E chondrites have been examined. It is concluded that there is no simple equilibrium process which can explain all their fundamental properties. The nearest would seem to involve a complex accretion history, whereby metal and silicates which ceased to equilibrate at high temperatures and pressures (say about 1200–1600°K and about 1 atm) were mixed with material which ceased to equilibrate at the same pressures but over the temperature range 600–700°K. In this way the level of reduction displayed by this class, and the fractionation of several major, minor, and trace elements, may be explained. It is difficult to escape the conclusion that two assemblages are required, even if it is assumed that these meteorites formed from a gas of nonsolar composition. However, when the lithophile element fractionation and uncertainties in the thermodynamic and cosmic abundance data are taken into account, it is possible that the gas from which this meteorite class formed had a cosmic composition prior to the beginning of condensation.