High Temperature Matter and Gamma Ray Spectra from Microscopic Black Holes

The relativistic viscous fluid equations describing the outflow of high temperature matter created via Hawking radiation from microscopic black holes are solved numerically for a realistic equation of state. We focus on black holes with initial temperatures greater than 100 GeV and lifetimes less than 6 days. The spectra of direct photons and photons from $\pi^0$ decay are calculated for energies greater than 1 GeV. We calculate the diffuse gamma ray spectrum from black holes distributed in our galactic halo. However, the most promising route for their observation is to search for point sources emitting gamma rays of ever-increasing energy.Comment: 33 pages, 13 figures, to be submitted to PR

Calculation of the emergent spectrum and observation of primordial black holes

We calculate the emergent spectrum of microscopic black holes, which emit copious amounts of thermal ``Hawking'' radiation, taking into account the proposition that (contrary to previous models) emitted quarks and gluons do not directly fragment into hadrons, but rather interact and form a photosphere and decrease in energy before fragmenting. The resulting spectrum emits copious amount of photons at energies around 100MeV. We find that the limit on the average universal density of black holes is not significantly affected by the photosphere. However we also find that gamma ray satellites such as EGRET and GLAST are well suited to look for nearby black holes out to a distance on the order of 0.3 parsecs, and conclude that if black holes are clustered locally as much as luminous matter, they may be directly detectable.Comment: 10 pages, Latex, submitted to PR

Effect of Finite Mass on Primordial Nucleosynthesis

We have calculated the small effect of finite nucleon mass on the weak-interaction rates that interconvert protons and neutrons in the early Universe. We have modified the standard code for primordial nucleosynthesis to include these corrections and find a small, systematic increase in the 4He yield, $\delta Y / Y \simeq (0.47 - 0.50)$, depending slightly on the baryon-to-photon ratio. The fractional changes in the abundances of the other light elements are a few percent or less for interesting values of the baryon-to-photon ratio.Comment: 15 pages, 8 figures, uses psfig.st

Cosmological Consequences of Slow-Moving Bubbles in First-Order Phase Transitions

In cosmological first-order phase transitions, the progress of true-vacuum bubbles is expected to be significantly retarded by the interaction between the bubble wall and the hot plasma. We examine the evolution and collision of slow-moving true-vacuum bubbles. Our lattice simulations indicate that phase oscillations, predicted and observed in systems with a local symmetry and with a global symmetry where the bubbles move at speeds less than the speed of light, do not occur inside collisions of slow-moving local-symmetry bubbles. We observe almost instantaneous phase equilibration which would lead to a decrease in the expected initial defect density, or possibly prevent defects from forming at all. We illustrate our findings with an example of defect formation suppressed in slow-moving bubbles. Slow-moving bubble walls also prevent the formation of `extra defects', and in the presence of plasma conductivity may lead to an increase in the magnitude of any primordial magnetic field formed.Comment: 10 pages, 7 figures, replaced with typos corrected and reference added. To appear in Phys. Rev.

Phase Equilibration and Magnetic Field Generation in U(1) Bubble Collisions

We present the results of lattice computations of collisions of two expanding bubbles of true vacuum in the Abelian Higgs model with a first-order phase transition. New time-dependent analytical solutions for the Abelian field strength and the phase of the complex field are derived from initial conditions inferred from linear superposition and are shown to be in excellent agreement with the numerical solutions especially for the case where the initial phase difference between the bubbles is small. With a step-function approximation for the initial phase of the complex field, solutions for the Abelian field strength and other gauge-invariant quantities are obtained in closed form. Possible extensions of the solution to the case of the electroweak phase transition and the generation of primordial magnetic fields are briefly discussed.Comment: LaTeX, 41 pages, 6 figures, submitted to Physical Review

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

Relativistic Viscous Fluid Description of Microscopic Black Hole Wind

Microscopic black holes explode with their temperature varying inversely as their mass. Such explosions would lead to the highest temperatures in the present universe, all the way to the Planck energy. Whether or not a quasi-stationary shell of matter undergoing radial hydrodynamic expansion surrounds such black holes is been controversial. In this paper relativistic viscous fluid equations are applied to the problem. It is shown that a self-consistent picture emerges of a fluid just marginally kept in local thermal equilibrium; viscosity is a crucial element of the dynamics.Comment: 11 pages, revte

Precision Prediction for the Big-Bang Abundance of Primordial Helium

Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of \he to a theoretical uncertainty of less than 0.1 \pct $(\delta Y_P < \pm 0.0002)$, improving the current theoretical precision by a factor of 10. At this accuracy the uncertainty in the abundance is dominated by the experimental uncertainty in the neutron mean lifetime, $\tau_n = 885.4 \pm 2.0 sec$. The following physical effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon-mass corrections to the weak rates; order-$\alpha$ quantum-electrodynamic correction to the plasma density, electron mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosynthesis code designed to control numerical errors to be less than 0.1\pct. Our predictions for the \EL[4]{He} abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, $Y_P(\eta = 5\times 10^{-10}) = 0.2462 \pm 0.0004 (expt) \pm < 0.0002 (theory)$. Further, the baryon density inferred from the Burles-Tytler determination of the primordial D abundance, $\Omega_B h^2 = 0.019\pm 0.001$, leads to the prediction: $Y_P = 0.2464 \pm 0.0005 (D/H) \pm < 0.0002 (theory) \pm 0.0005 (expt)$. This ``prediction'' and an accurate measurement of the primeval \he abundance will allow an important consistency test of primordial nucleosynthesis.Comment: Replaced fitting formulas - new versions differ by small but significant amount. Other minor changes. 30 pages, 17 figures, 5 table

Gravitational Waves from Mesoscopic Dynamics of the Extra Dimensions

Recent models which describe our world as a brane embedded in a higher dimensional space introduce new geometrical degrees of freedom: the shape and/or size of the extra dimensions, and the position of the brane. These modes can be coherently excited by symmetry breaking in the early universe even on ``mesoscopic'' scales as large as 1 mm, leading to detectable gravitational radiation. Two sources are described: relativistic turbulence caused by a first-order transition of a radion potential, and Kibble excitation of Nambu-Goldstone modes of brane displacement. Characteristic scales and spectral properties are estimated and the prospects for observation by LISA are discussed. Extra dimensions with scale between 10 \AA and 1 mm, which enter the 3+1-D era at cosmic temperatures between 1 and 1000 TeV, produce backgrounds with energy peaked at observed frequencies in the LISA band, between $10^{-1}$ and $10^{-4}$ Hz. The background is detectable above instrument and astrophysical foregrounds if initial metric perturbations are excited to a fractional amplitude of $10^{-3}$ or more, a likely outcome for the Nambu-Goldstone excitations.Comment: Latex, 5 pages, plus one figure, final version to appear in Phys. Rev. Let

Primordial black holes under the double inflationary power spectrum

Recently, it has been shown that the primordial black holes (PBHs) produced by near critical collapse in the expanding universe have a scaling mass relation similar to that of black holes produced in asymptotically flat spacetime. Distinct from PBHs formed with mass about the horizon mass (Type I), the PBHs with the scaling relation (Type II) can be created with a range of masses at a given formation time. In general, only the case in which the PBH formation is concentrated at one epoch has been considered. However, it is expected that PBH formation is possible over a broad range of epochs if the density fluctuation has a rather large amplitude and smooth scale dependence. In this paper, we study the PBH formation for both types assuming the power spectrum of double inflationary models in which the small scale fluctuations could have large amplitudes independent of the CMBR anisotropy. The mass spectrum of Type II PBHs is newly constructed without limiting the PBH formation period. The double inflationary power spectrum is assumed to be of double simple power-law which are smoothly connected. Under the assumed power spectrum, the accumulation of small PBHs formed at later times is important and the mass range is significantly broadened for both Types. The PBH mass spectra are far smoother than the observed MACHO spectrum due to our assumption of a smooth spectrum. In order to fit the observation, a more spiky spectrum is required.Comment: 7 pages including 2 figures, to be published in Phys. Rev.