White holes as the asymptotic limit of evaporating primordial black holes (original) (raw)
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A new constraint on the Hawking evaporation of primordial black holes in the radiation-dominated era
The European Physical Journal C
In this paper, we revisit the evaporation and accretion of primordial black holes (PBHs) during cosmic history and compare them to see if both of these processes are constantly active for PBHs or not. Our calculations indicate that during the radiation-dominated era, PBHs absorb ambient radiation due to accretion, and their apparent horizon grows rapidly. This growth causes the Hawking radiation process to practically fail and all the particles that escape as radiation from PBHs to fall back into them. Nevertheless, our emphasis is that the accretion efficiency factor also plays a very important role here and its exact determination is essential. We have shown that the lower mass limit for PBHs that have not yet evaporated should approximately be 10^{14}g1014gratherthan10 14 g rather than1014gratherthan10^{15}g$$ 10 15 g . Finally, we study the effects of Hawking radiation quiescence in cosmology and reject models based on the evaporation of PBHs in the radiation-dominated era.
Evolution of primordial black holes in a radiation and phantom energy environment
General Relativity and Gravitation 40(8), 1596-1602, 2008
In this work we extend previous work on the evolution of a primordial black hole (PBH) to address the presence of a dark energy component with a super-negative equation of state as a background, investigating the competition between the radiation accretion, the Hawking evaporation and the phantom accretion, the latter two causing a decrease on black hole mass. It is found that there is an instant during the matter-dominated era after which the radiation accretion becomes negligible compared to the phantom accretion. The Hawking evaporation may become important again depending on a mass threshold. The evaporation of PBHs is quite modified at late times by these effects, but only if the generalized second law of thermodynamics is violated.
Primordial black holes as a probe of cosmology and high energy physics
Quantum Gravity, 2003
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. ...
Primordial Black Holes in the Very Early Universe
The formation of Primordial Black Holes is a robust prediction of several gravitational theories. Whereas the creation of PBHs was very active in the remote past, such process seem to be very negligible at the present epoch. In this work, we estimate the effects from the radiation surrounding PBHs due to the absorption term in the equations that describe how their masses depend on time. The Hawking radiation contributes with mass loss and the absorption term contributes with gain, but a interesting competition between these terms is analysed. These effects are included in the equations describing PBHs and its mass density as the universe evolves in time and the model is able to describes the evolution of the numerical density of PBHs and the mass evolution and comparisons with cosmological constraints set upper limits in their abundances. Moreover, we evaluate the fraction of PBHs (in terms of the critical density) formed from the high-energy collision of particles before Inflation, when the temperatures were close to Planck values. We consider that the Universe has dimension D, and we evaluate the e-folds number in order get a universe free from such Primordial Black Holes. Finally, the Holographic constraint is used to estimate upper bounds to temperature and mass of PBHs with monochromatic spectrum.
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.
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.