White holes as the asymptotic limit of evaporating primordial black holes (original) (raw)
Calculation of the Emergent Spectrum and Observation of Primordial Black Holes
Physical Review Letters, 1997
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.
Quantum-gravity phenomenology with primordial black holes
arXiv: General Relativity and Quantum Cosmology, 2015
Quantum gravity may allow black holes to tunnel into white holes. If so, the lifetime of a black hole could be shorter than the one given by Hawking evaporation, solving the information paradox. More interestingly, this could open to a new window for quantum-gravity phenomenology, in connection with the existence of primordial black holes. We discuss in particular the power of the associated explosion and the possibility to observe an astrophysical signal in the radio and in the gamma wavelengths.
Primordial black holes-recent developments
Arxiv preprint astro-ph/0504034, 2005
Recent developments in the study of primordial black holes (PBHs) will be reviewed, with particular emphasis on their formation and evaporation. PBHs could provide a unique probe of the early Universe, gravitational collapse, high energy physics and quantum gravity. Indeed their study may place interesting constraints on the physics relevant to these areas even if they never formed. In the "early Universe" context, particularly useful constraints can be placed on inflationary scenarios, especially if evaporating PBHs leave stable Planck-mass relicts. In the "gravitational collapse" context, the existence of PBHs could provide a unique test of the sort of critical phenomena discovered in recent numerical calculations. In the "high energy physics" context, information may come from gamma-ray bursts (if a subset of these are generated by PBH explosions) or from cosmic rays (if some of these derive from evaporating PBHs). In the "quantum gravity" context, the formation and evaporation of small black holes could lead to observable signatures in cosmic ray events and accelerator experiments, providing there are extra dimensions and providing the quantum gravity scale is around a TeV.
2008
Possibilities of an experimental search for gamma-ray bursts from primordial black hole (PBH) evaporations in space are reconsidered. It is argued that the corresponding constraints which can be obtained in experiments with cosmic ray detectors strongly depend on theoretical approach used for a description of the PBH evaporation process. Predictions of several theoretical models for gamma-ray spectra from final stages of PBH life (integrated over time) are given.
Evolution of a primordial black hole population
Physical Review D, 1998
We reconsider in this work the effects of an energy absorption term in the evolution of primordial black holes (hereafter PBHs) in the several epochs of the Universe. A critical mass is introduced as a boundary between the accreting and evaporating regimes of the PBHs. We show that the growth of PBHs is negligible in the Radiation-dominated Era due to scarcity of energy density supply from the expanding background, in agreement with a previous analysis by Carr and Hawking, but that nevertheless the absorption term is large enough for black holes above the critical mass to preclude their evaporation until the universe has cooled sufficiently. The effects of PBH motion are also discussed: the Doppler effect may give rise to energy accretion in black-holes with large peculiar motions relative to background. We discuss how cosmological constraints are modified by the introduction of the critical mass since that PBHs above it do not disturb the CMBR. We show that there is a large range of admissible masses for PBHs above the critical mass but well below the cosmological horizon. Finally we outline a minimal kinetic formalism, solved in some limiting cases, to deal with more complicated cases of PBH populations.
Observational Characteristics of the Final Stages of Evaporating Primordial Black Holes
Proceedings of The 34th International Cosmic Ray Conference — PoS(ICRC2015)
Primordial black holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all energetically allowed species of fundamental particles thermally. PBHs with initial masses of order 5x10 15 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high-energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. A search of five years of Milagro data set a local (parsec-scale) upper limit of 3.6x10 4 PBH bursts/year/pc3. We will also report the sensitivity of the High-Altitude Water-Cherenkov (HAWC) observatory to PBH evaporation events. Finally, we investigate the final few seconds of black hole evaporation using Standard Model physics and calculate energy dependent PBH burst time profiles in GeV/TeV range. We calculate PBH burst light curves observable by HAWC and explore search methods and potentially unique observational signatures of PBH bursts.
Some results on the evolution of primordial black holes
Brazilian Journal of Physics, 2005
We briefly review some recent results related to thermodynamics of semiclassical black holes applied to their primordial formation. Issues on the existence of an influx of ambient particles onto the PBHs, which may help grow them, are addressed. We revisit the integrated flux from evaporated PBHs contributing to the present backgrounds and show that there probe mass scales which are otherwise poorly constrained. Finally the Generalized Second Law of Thermodynamics and the Holographic Principle are combined to show that if some form of the latter holds, strong upper bounds to the mass density of PBHs formed in the early universe may be obtained, especially for inflationary cosmological models. This method is completely independent from those based on the background fluxes and applies to potentially important epochs of PBH formation, resulting in quite strong constraints to Ω pbh .
Possible quantum instability of primordial black holes
Physical Review D, 1999
Evidence for the possible existence of a quantum process opposite to the famous Hawking radiation (evaporation) of black holes is presented. This new phenomenon could be very relevant in the case of exotic multiple horizon Nariai black holes and in the context of common grand unified theories. This is clearly manifested in the case of the SO(10) GUT, that is here investigated in detail. The remarkable result is obtained, that anti-evaporation can occur there only in the SUSY version of the theory. It is thus concluded that the existence of primordial black holes in the present Universe might be considered as an evidence for supersymmetry.
Research in Astronomy and Astrophysics, 2010
Primordial black holes (PBHs) are a profound signature of primordial cosmological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to restrict a wide range of particle physics models, predicting an enhancement of the ultraviolet part of the spectrum of density perturbations, early dust-like stages, first order phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflationary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds.
Revisiting Primordial Black Hole Evolution
Axioms
Primordial black holes (PBHs) are the sensitive probe for physics and cosmology of very early Universe. The observable effect of their existence depends on the PBH mass. Mini PBHs evaporate and do not survive to the present time, leaving only background effect of products of their evaporation, while PBHs evaporating now can be new exotic sources of energetic particles and gamma rays in the modern Universe. Here we revisit the history of evolution of mini PBHs. We follow the aspects associated with growth versus evaporation rate of “a mini PBH being trapped inside intense local cosmological matter inhomogeneity”. We show that the existence of baryon accretion forbidden black hole regime enables constraints on mini PBHs with the mass M ≤ 5.5 × 10 13 g. On the other hand, we propose the mechanism of delay of evaporation of primordial population of PBHs of primordial mass range 5.5 × 10 13 g ≤ M ≤ 5.1 × 10 14 g. It can provide their evaporation to be the main contributor to γ -ray flux ...