Jane H. MacGibbon

Cosmic rays from primordial black holes

The quark and gluon emission from primordial black holes (PBHs) which may have formed from initial density perturbations or phase transitions in the early universe are investigated. If the PBHs formed from scale-invariant initial density perturbations in the radiation dominated era, it is found that the emission can explain or contribute significantly to the extragalactic photon and interstellar cosmic-ray electron, positron, and antiproton spectra around 0.1{minus}1 GeV. In particular, the PBH emission strongly resembles the cosmic-ray gamma-ray spectrum between 50 and 170 MeV. The upper limits on the PBH density today from the gamma-ray, e(+), e({minus}), and antiproton data are comparable, provided that the PBHs cluster to the same degree as the other matter in the Galactic halo. 130 refs.

Cosmic rays from primordial black holes and constraints on the early universe

Abstract The constraints on the number of evaporating primordial black holes imposed by observations of the cosmological gamma-ray background do not exclude their making a significant contribution to the Galactic flux of cosmic ray photons, electrons, positrons and antiprotons. Even if this contribution is small, cosmic ray data place important limits on the number of evaporating black holes and thereby on models of the early Universe. Evaporating black holes are unlikely to be detectable in their final explosive phase unless new physics is invoked at the QCD phase transition.

High energy neutrino flux from ordinary cosmic strings

Abstract We calculate the flux of ultrahigh energy neutrinos from ordinary (i.e. non-superconducting) cosmic strings and compare the results with the most recent observational constraints. For heavy strings (where the mass per unit length is determined by the scale of grand unification) the predicted flux is below the present observational limits. However, sufficiently light strings may be detectable by this mechanism. Our calculations give only upper limits for the neutrino flux, since the source of the neutrinos, jets from particle production at cusps, may be weakened by back-reaction effects.

High-energy neutrinos, photons and cosmic ray fluxes from VHS cosmic strings

Decaying topological defects, in particular cosmic strings, can produce a significant flux of high energy neutrinos, photons and cosmic rays. According to the prevailing understanding of cosmic string dynamics in an expanding Universe, the network of long strings loses its energy first into string loops, which in turn give off most of their energy as gravitational radiation. However, it has been suggested by Vincent, Hindmarsh, and Sakellariadou (VHS) that particle emission may be the dominant energy loss channel for the long string network. In this case, the predicted flux of high energy particles would be much larger. Here we calculate the predicted flux of high energy gamma rays, neutrinos and cosmic ray antiprotons and protons as a function of the scale of symmetry breaking

Limits on black hole formation from cosmic string loops

\ensuremath{\eta}

Gamma-ray signatures from ordinary cosmic strings

at which the strings are produced and as a function of the initial energy

Black Hole Constraints on Varying Fundamental Constants

{m}_{J}

Observational Characteristics of the Final Stages of Evaporating Primordial Black Holes

of the particle jets which result from the string decay. Assuming the validity of the VHS scenario, we find that due to the interactions with the cosmic radiation backgrounds all fluxes but the neutrino flux are suppressed at the highest energies. This indicates that the observed events above the GZK cutoff can only be accounted for in this scenario if the primary particle is a neutrino and

DO EVAPORATING 4D BLACK HOLES FORM PHOTOSPHERES AND/OR CHROMOSPHERES?

\ensuremath{\eta}

SENSITIVITY OF THE FERMI DETECTORS TO GAMMA-RAY BURSTS FROM EVAPORATING PRIMORDIAL BLACK HOLES (PBHS)

is somewhat less than the GUT scale, i.e.