Signatures for a cosmic flux of magnetic monopoles

Any early Universe phase transition occurring after inflation has the potential to populate the Universe with relic magnetic monopoles. Observations of galactic magnetic fields, as well as observations matched with models for extragalactic magnetic fields, lead to the conclusion that monopoles of mass 10¹⁵ GeV are accelerated in these fields to relativistic velocities. We explore the possible signatures of a cosmic flux of relativistic monopoles impinging on the Earth. The electromagnetically induced signatures of monopoles are reliable. The hadronically induced signatures are highly model-dependent. Among our findings are (i) the electromagnetic energy losses of monopoles continuously initiate a protracted shower of small intensity; (ii) monopoles may traverse the Earth’s diameter, making them a probe of the Earth’s interior structure; (iii) in addition to the direct monopole Cherenkov signal presently employed, a very attractive search strategy for monopoles is detection of their coherent radio-Cherenkov signal produced by the charge-excess in the e⁺–e⁻ shower––in fact, Cherenkov-detectors have the potential to discover a monopole flux (or limit it) several orders of magnitude below the theoretical Parker limit of 10⁻¹⁵ cm⁻² s⁻¹ sr⁻¹; (iv) it is conceivable (but not compelling) that bound states of colored monopoles may be the primary particles initiating the air showers observed above the GZK cutoff.     

The fluctuation origin of cosmic radiation

We have investigated the origin of cosmic radiation in terms of a sudden injection of particles in time, momentum and space. The appropriate boundary conditions for the various regions through which the particles pass were used. With all of the acceleration within a turbulent region, we find that the observed spectrum is explained by a continuous deceleration in which statistical fluctuations dominate. This is contradictory to the usual assumptions in which fluctuations do not play an important part. We find that the time dependent solution has an exponent of the power law spectrum that varies weakly with the momentum and time. The steady state solution shows the usual constant exponent.This work was supported by the National Aeronautics and Space Administration under Grant NsG-695.     

The dipole anisotropy of the cosmic microwave background radiation

We review the prediction, discovery and precise measurements of CMB Dipole Anisotropy, a field in which Dennis Sciama has provided important initial insight.     

The cosmic microwave background radiation in a non-expanding universe

During the nineteenth century, it was common for physicists to believe in the existence of a material vacuum composed of an incompressible fluid that fills the whole universe. This fluid was called the aether. Its original purpose was to provide an elastic tenuous medium for light propagation through space. Although it is well understood today that no such medium is needed for light propagation, the existence of a cosmic aether medium in space is still possible and its physical properties can be understood on models of cosmology that have nothing to do with Big-Bang cosmology. It is possible that electromagnetic radiation emitted by the cosmic aether medium has already been detected. The low-frequency electromagnetic radiation emitted by the aether is called the cosmic microwave background radiation. The present study outlines a model for an aether medium that explains the genesis of the microwave background radiation in a closed static (nonexpanding) universe. It is shown that the spectrum of the microwave background radiation is a perfect blackbody with a temperature T _rad=2.77 K in harmony with the perfect cosmological principle. It is further shown that the aether medium is opaque at radio and microwave frequencies. This particular feature of the model does not contradict any observations regarding the existence of distant radio galaxies and quasars.     

Annihilation radiation in cosmic gamma-ray bursts

The emission features observed in the energy spectra of cosmic gamma-ray bursts imply the existence of two radiation components of comparable intensity. The softer component is similar to the continua of featureless bursts. The fast decrease in the intensity of this radiation with increasing photon energy is apparently due to the neutron star's magnetosphere being opaque to hard photons because of the formation of electron-positron pairs in single- (,B) and two-photon (,), processes. The hard component originates from the annihilation of electron-positron pairs, its spectrum representing a broad line with an extended power-law wing. Such a shape of the spectrum is apparently due to either thermal broadening in a source with a spatially inhomogeneous and rapidly time-varying plasma temperature, or nonthermal energy distribution of particles in their motion along the magnetic field lines. It is assumed that the sources of these components are spatially separated, the annihilation radiation escaping from the polar regions of a strongly magnetized neutron star in a collimated beam without appreciable attenuation.     

Secondary production of antiprotons in cosmic radiation

A reliable representation to the invariant cross-section for the production of antiprotons ( ) in inclusive reactions has been obtained, which fits the data extremely well from threshold to ISR energies. Using this, the production spectrum of by cosmic ray interaction with interstellar gas is calculated and is compared with other existing calculations. The equilibrium spectrum in the Galaxy has been derived from about 100 MeV to a few hundred GeV in kinetic energy using Leaky Box Model for the propagation of cosmic rays, by taking into account all energy loss processes. It is found that /P ratio calculated here is very much smaller than the observed ratio. In view of the fact that this excess of observed /P ratio is much larger than the measured upper limits on the fraction of antimatter in the form of antinuclei, the excess /P ratio has not been attributed to the existence of antimatter. Instead, it is shown that Closed Galaxy Model for the propagation of cosmic rays predicts more antiprotons than observed. Therefore, it is suggested that if cosmic rays contain about 50% new component of local origin, the resulting Closed Galaxy Model explains well the observations. The present calculations also predict too small a flux of below a few hundred MeV to make this energy region ideally suited to look for antiprotons of primordial origin.     

The anomalous distribution in heliocentric longitude of solar injected cosmic radiation

Concurrent observations of the solar flare of March 12, 1969 by two spacecrafts separated in solar longitude by 38° show that the accessibility at 1 AU to cosmic ray particles is not a simple function of the relative solar longitude. The cosmic ray flux, degree of anisotropy, and rise time all indicate that the favored path for cosmic ray propagation in this event was some 40° to the east of the nominal Archimedes spiral line of force from the flare location. This is interpreted as evidence for either (a) extreme stochastical wandering of the lines of force of the interplanetary magnetic field, or (b) the redistribution of the cosmic rays in coronal magnetic fields prior to escape onto the nominal Archimedes spiral lines of force.Now at CSIRO, G.P.O. Box 124, Port Melbourne, Victoria 3207, Australia.Now at Physical Research Laboratory, Ahmedabad, India.     

Testing isotropy of cosmic microwave background radiation

We introduce new symmetry-based methods to test for isotropy in cosmic microwave background (CMB) radiation. Each angular multipole is factored into unique products of power eigenvectors, related multipoles and singular values that provide two new rotationally invariant measures mode by mode. The power entropy and directional entropy are new tests of randomness that are independent of the usual CMB power. Simulated Galactic plane contamination is readily identified. The ILC– WMAP data maps show seven axes well aligned with one another and the direction Virgo. Parameter free statistics find 12 independent cases of extraordinary axial alignment, low power entropy, or both having 5 per cent probability or lower in an isotropic distribution. Isotropy of the ILC maps is ruled out to confidence levels of better than 99.9 per cent, whether or not coincidences with other puzzles coming from the Virgo axis are included. Our work shows that anisotropy is not confined to the low l region, but extends over a much larger l range.     

Polarization of the cosmic background radiation and secondary ionization of the cosmic medium

We discuss the properties of the cosmic background polarization as predicted by secondary ionization models, and the prospects for the determination of reheating parameters from forthcoming space experiments.     

Lasting recombination and cosmic background radiation spectrum

The thermal decoupling during recombination and the endurance of this process can significantly deform the black-body background radiation spectrum even in the absence of heating sources. Observational data contradicts a flat standard universe but agrees with a low-density model and with a flat matter-antimatter symmetric universe. Evidence is presented against the presumption that matter-antimatter annibilation should necessarily produce large distortions.     

The composition of low energy primaries withZ≥9 in cosmic radiation

Photometric mean track width measurements have been made on 81 primary particles (Z9) stopping in a nuclear emulsion stack exposed at 2.7 g/cm² of residual atmosphere at Fort Churchill, Canada. The standard deviation of the charge determinations amounts to 0.14 units of charge for oxygen and increases to 0.40 units for iron nuclei when 10 mm track is measured. The relative abundances of the nuclei in the charge interval 8Z14 are given for the energy interval 250–400 MeV/nucleon, and comparisons are performed with the results of other measurements. The VH-particles are dominated by iron. The distribution of the VH-particles seems to be consistent with the assumption that the VH-nuclei have in the mean passed through only 1.6±0.5 g/cm² interstellar matter.     

The composition of the cosmic radiation and the atomic properties of the elements

The composition of the primordial cosmic radiation has been compared with the solar system composition and that of interstellar matter. It is found that the overabundance of an element in the radiation is approximately proportional to the cross-section for the ionization of neutral atoms of that element through fast charged particle impacts. The results strongly support the assumption that the selection of cosmic ray particles is governed by the atomic properties of the elements.     

Spacecraft measurement of Forbush decreases in the cosmic radiation

The Forbush decrease in the cosmic radiation has been measured by a charged-particle monitor (E _p )> 50 MeV) on board the OGO-6 satellite. For the events of June 7–10, September 27–30, and November 21–December 6, 1969, the Forbush decrease totalled 4.6, 6, and 6% in amplitude, respectively, for the Mt. Washington neutron monitor (P _c = 1.24 GV), and 5.2, 13, and 16%, respectively, for the OGO-6 charged-particle monitor in the polar region (P _c < 0.3 GB). The depression in the OGO-6 charged-particle monitor was larger at higher geomagnetic latitudes than at lower latitudes. However, for the events of June 7–10 and November 21–December 6, 1969, the Forbush decrease totalled 20 and 15% in amplitude respectively for the Pioneer 8 cosmic-ray telescope (P _c > 0.4 GV), which was at the respective distances of 1.08 AU and 1 AU from the Sun. These results indicate that the Forbush decrease has greater effects on lower-energy charged particles, the magnitude of the effect also depending on the location of the detector with respect to the modulating region.The spacecraft data near Earth also showed that, for vertical cut-off rigidities P _c 1.8 GV, the total percentage decrease in the amplitudes of the Forbush decreases can be represented by –mP _c + k, where m and k are each constant for the particular Forbush decrease but which increase with increasing Mt. Washington neutron monitor monthly average rates, an indication of a flattening of the rigidity dependence of Forbush decreases towards maximum solar modulation.     

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.     

The relative energy spectra of carbon and oxygen nuclei in the primary cosmic radiation

Measurements of the energy spectra of carbon and oxygen nuclei in the primary cosmic radiation over the energy range from 140 MeV/nuc to 30 BeV/nuc are reported. An average C/O ratio of 1.11±0.02 is obtained at the top of the atmosphere. This ratio is found to be constant to within 5% over the entire energy range. The energy spectra of these two nuclei are presented and compared with earlier measurements and with satellite observations at low energies. After correction for propagational effects in 4 g/cm² of interstellar hydrogen the source C/O ratio is found to be 0.9. The astrophysical implications of this C/O ratio are discussed.     

The motion of charged particles in a strong electromagnetic field and curvature radiation

The features of the relativistic charge particle motion and emission due to the radiative slamping in the strong electromagnetic fields are investigated. It is shown that the radiative force responsible for curvature radiation is associated with the particle drift in an inhomogeneous magnetic field. The adiabatic trajectory is obtained for the relativistic particle, moving in a strong static electron-magnetic field, particle energy being determined by the balance of the work of the electric field and the energy losses through curvature radiation.