Pair Production By Primordial Black Hole Evaporation

Here we investigate the evaporation of a 8.2 _ 1010 kg primordial black hole. This mass is shown to satifisfy the compactness parameter constraint L/R ≥ 1031 ergscm−1s−1. We assume only photon-photon production according to a Planck distribution. We calculate the distance from the black hole at which the optical depth due to photon-photon collisions to produce positron/electron pairs becomes unity in which a pair plasma is produced within a volume of inner radius of 90RS and outer radius 123000RS respectively. We then calculate corresponding positron/electron production rates, production rate densities, and optical depth rates due to subsequent Compton scattering by photons. We quantitatively investigate annihilation rate densities and number of annihilations for number densities generated by an initially static fireball that after a time △tL = 5 _ 10−20s is allowed to propagate radially at the speed of light. We show that the annihilation rate per particle is given by \u3c σv \u3e= 1.2_10−39m3s−1 where we approximate cos θ ≈ 1 between positron and electron collisions and derive a probability distribution function by Monte Carlo methods for positron and electron velocities sourced by field and target photons emitted by the black hole given by the approximation γ += γ− ≈ (E+ε)/(2mec2) whose corresponding velocities are directed radially. We show that no annihilations occur within the expanding fireball and that electrons and positrons freely stream from the proximity of the BH. We investigate the spectra produced by different mass (thermal energy) BH\u27s that are currently evaporating. We analyze their limiting behavior and compare with blackbody emission from stars. We then discuss detection methods and limitations from possible gamma ray and positron sources including the 511 keV line emission from the galactic center, high energy cosmic ray positron production, and direct gamma ray burst events

Can we observe fuzzballs or firewalls?

In the fuzzball paradigm the information paradox is resolved because the black hole is replaced by an object with no horizon. One may therefore ask if observations can distinguish a traditional hole from a fuzzball. We find: (a) It is very difficult to reflect quanta off the surface of a fuzzball, mainly because geodesics starting near the horizon radius cannot escape to infinity unless their starting direction is very close to radial. (b) If infalling particles interact with the emerging radiation before they are engulfed by the horizon, then we say that we have a `firewall behavior'. We consider several types of interactions, but find no evidence for firewall behavior in any theory that obeys causality. (c) Photons with wavelengths {\it larger} than the black hole radius can be scattered off the emerging radiation, but a very small fraction of the backscattered photons will be able to escape back to infinity.Comment: 52 pages, 4 figure

Full action of two deformation operators in the D1D5 CFT

We are interested in thermalization in the D1D5 CFT, since this process is expected to be dual to black hole formation. We expect that the lowest order process where thermalization occurs will be at second order in the perturbation that moves us away from the orbifold point. The operator governing the deformation off of the orbifold point consists of a twist operator combined with a supercharge operator acting on this twist. In a previous paper we computed the action of two twist operators on an arbitrary state of the CFT. In the present work we compute the action of the supercharges on these twist operators, thereby obtaining the full action of two deformation operators on an arbitrary state of the CFT. We show that the full amplitude can be related to the amplitude with just the twists through an action of the supercharge operators on the initial and final states. The essential part of this computation consists of moving the contours from the twist operators to the initial and final states; to do this one must first map the amplitude to a covering space where the twists are removed, and then map back to the original space on which the CFT is defined.Comment: 48 pages, 2 figure

Lifting of D1-D5-P states

We consider states of the D1-D5 CFT where only the left-moving sector is excited. As we deform away from the orbifold point, some of these states will remain BPS while others can `lift'. We compute this lifting for a particular family of D1-D5-P states, at second order in the deformation off the orbifold point. We note that the maximally twisted sector of the CFT is special: the covering surface appearing in the correlator can only be genus one while for other sectors there is always a genus zero contribution. We use the results to argue that fuzzball configurations should be studied for the full class including both extremal and near-extremal states; many extremal configurations may be best seen as special limits of near extremal configurations.Comment: 51 pages, 6 figure

Bootstrapping multi-wound twist effects in symmetric orbifold CFTs

We investigate the effects of the twist-2 operator in 2D symmetric orbifold CFTs. The twist operator can join together a twist-$M$ state and a twist-$N$ state, creating a twist-$(M+N)$ state. This process involves three effects: pair creation, propagation, and contraction. We study these effects by using a Bogoliubov ansatz and conformal symmetry. In this multi-wound scenario, pair creation no longer decouples from propagation, in contrast to the previous study where $M=N=1$. We derive equations for these effects, which organize themselves into recursion relations and constraints. Using the recursion relations, we can determine the infinite number of coefficients in the effects through a finite number of inputs. Moreover, the number of required inputs can be further reduced by applying constraints.Comment: 38 page

Inscribing geodesic circles on the face of the superstratum

We use families of circular null geodesics as probes of a family of microstate geometries, known as $(1,0,n)$ superstrata. These geometries carry a left-moving momentum wave and the behavior of some of the geodesic probes is very sensitive to this background wave. The left-moving geodesics behave like BPS particles and so can be placed in circular orbits anywhere in the geometry and actually "float" at fixed radius and angle in the three-dimensional "capped BTZ" geometry. The right-moving geodesics behave like non-BPS particles. We show that they provide a simple geometric characterization of the black-hole bound: when the momentum charge of the geometry is below this bound, such geodesics can be placed anywhere, but exceeding the bound, even by a small amount, means these geodesics are restricted to the deep interior of the geometry. We also show that for left-moving string probes, the tidal forces remain comparable with those of global AdS$_3$. Nevertheless, for some of these probes, the "bumps" in the geometry induce an oscillatory mass term and we discuss how this can lead to chaotic scrambling of the state of the string.Comment: 29 pages, 8 figure