Coordinated rocket and satellite observations of the solar corona

Coronal condensations associated with active regions are investigated by comparing their X-ray and EUV line intensities. The EUV line measurements were made with the OSO-H satellite, and the X-ray measurements were made with an ATM support rocket. The data obtained from these observations are used to find the emission measure distribution at low temperatures

Bulk and Brane Decay of a (4+n)-Dimensional Schwarzschild-De-Sitter Black Hole: Scalar Radiation

In this paper, we extend the idea that the spectrum of Hawking radiation can reveal valuable information on a number of parameters that characterize a particular black hole background - such as the dimensionality of spacetime and the value of coupling constants - to gain information on another important aspect: the curvature of spacetime. We investigate the emission of Hawking radiation from a D-dimensional Schwarzschild-de-Sitter black hole emitted in the form of scalar fields, and employ both analytical and numerical techniques to calculate greybody factors and differential energy emission rates on the brane and in the bulk. The energy emission rate of the black hole is significantly enhanced in the high-energy regime with the number of spacelike dimensions. On the other hand, in the low-energy part of the spectrum, it is the cosmological constant that leaves a clear footprint, through a characteristic, constant emission rate of ultrasoft quanta determined by the values of black hole and cosmological horizons. Our results are applicable to "small" black holes arising in theories with an arbitrary number and size of extra dimensions, as well as to pure 4-dimensional primordial black holes, embedded in a de Sitter spacetime.Comment: 31 pages, latex file, data files available at http://lpsc.in2p3.fr/ams/greybody/ some clarifying comments and references added, typos corrected, version to appear in Phys. Rev.

Radiation of Charged Particles by Charged Black Hole

The probability of a charged particle production by the electric field of a charged black hole depends essentially on the particle energy. This probability is found in the nonrelativistic and ultrarelativistic limits. The range of values for the mass and charge of a black hole is indicated where the discussed mechanism of radiation is dominating over the Hawking one.Comment: 10 pages, latex, 4 ps-figure

Critical Velocity in 3He-B Vibrating Wire Experiments as Analog of Vacuum Instability in a Slowly Oscillating Electric Field

The Lancaster experiments with a cylindrical wire moving in superfluid 3He-B are discussed, where the measured critical velocity of pair creation is much below the Landau critical velocity. The phenomenon is shown to be analogous to the instability of the electron-positron vacuum in an adiabatically alternating strong electric potential of both signs, where the positive- and negative-root levels cross and thus the instability treshold is twice less than in the conventional case of a single static potential well.Comment: RevTex file, 6 pages, 4 figure

The fate of Reissner-Nortstr\"{o}m black hole in the Einstein-Yang-Mills-Higgs system

We study about an evaporating process of black holes in SO(3) Einstein-Yang-Mills-Higgs system. We consider a massless scalar field which couple neither with the Yang-Mills field nor with the Higgs field surrounding the black hole. We discuss differences in evaporating rate between a monopole black hole and a Reissner-Nortstr\"{o}m (RN) black hole.Comment: 9 pages, 8 figure

High Energy Colliders as Black Hole Factories: The End of Short Distance Physics

If the fundamental Planck scale is of order a TeV, as the case in some extra-dimensions scenarios, future hadron colliders such as the Large Hadron Collider will be black hole factories. The non-perturbative process of black hole formation and decay by Hawking evaporation gives rise to spectacular events with up to many dozens of relatively hard jets and leptons, with a characteristic ratio of hadronic to leptonic activity of roughly 5:1. The total transverse energy of such events is typically a sizeable fraction of the beam energy. Perturbative hard scattering processes at energies well above the Planck scale are cloaked behind a horizon, thus limiting the ability to probe short distances. The high energy black hole cross section grows with energy at a rate determined by the dimensionality and geometry of the extra dimensions. This dependence therefore probes the extra dimensions at distances larger than the Planck scale.Comment: Latex, 28 pages. v4: minor changes, largely to agree with published version; appendix added comparing convention

Radio Observations of X-ray Sources

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe