Evaporation Of Primordial Black Holes Research Articles

Dark matter from evaporating primordial black holes in the early universe

Primordial Black Holes (PBHs) could dominate in the early universe and, evaporating before Big bang Nucleosynthesis, provide new freeze in mechanism of dark matter (DM) production. The proposed scenario is considered for two possible mechanisms of PBH formation and the corresponding continuous PBH mass spectra so that the effect of non-single PBH mass spectrum is taken into account in the results of PBH evaporation, by which PBH dominance in the early universe ends. We specify the conditions under which the proposed scenario can explain production of dark matter in very early universe.

Quantum effects on the evaporation of PBHs: contributions to dark matter

We compute the relic abundance of dark matter in the presence of Primordial Black Holes (PBHs) beyond the semiclassical approximation. We take into account the quantum corrections due to the memory burden effect, which is assumed to suppress the black hole evaporation rate by the inverse power of its own entropy. Such quantum effect significantly enhances the lifetime, rendering the possibility of PBH mass ≲ 109 g being the sole dark matter (DM) candidate. However, Nature can not rule out the existence of fundamental particles such as DM. We, therefore, include the possibility of populating the dark sector by the decay of PBHs to those fundamental particles, adding the contribution to stable PBH whose lifetime is extended due to the quantum corrections. Depending on the strength of the burden effect, we show that a wide range of parameter space opens up in the initial PBH mass and fundamental dark matter mass plane that respects the correct relic abundance.

Non-thermal WIMPy baryogenesis with primordial black hole

We consider the possibility that the weakly interacting massive particles produced from the evaporation of primordial black hole can explain both the relic density of dark matter and the baryon asymmetry of the Universe, through their annihilation which violate B and CP-symmetry. We find that the primordial black hole with mass less than 107g is a good candidate as an source of TeV dark matter with the total annihilation cross section 〈σaυ〉 ≲ 10-7 GeV-2 and the B-violating scattering cross section 〈σaυ〉 ≲ 2 × 10-9 GeV-2. This large annihilation cross section of dark matter in this model would make it available to search them in the indirect search for dark matter such as gamma-ray or neutrino observations.

Wash-in leptogenesis after the evaporation of primordial black holes

Wash-in leptogenesis is a powerful mechanism to generate the baryon asymmetry of the Universe that treats right-handed-neutrino interactions on the same footing as electroweak sphaleron processes: as mere spectator processes acting on the background of chemical potentials in the Standard Model plasma. Successful wash-in leptogenesis requires this chemical background to be CP-violating, which can be achieved by violating any of the more than ten global charges that are conserved in the Standard Model at very high temperatures. In this paper, we demonstrate that the primordial charge asymmetries required for wash-in leptogenesis can be readily produced by evaporating primordial black holes (PBHs). Our argument is based on the fact that the Hawking radiation emitted by PBHs contains more or less any state in the particle spectrum. Therefore, if heavy states with CP-violating decays are present in the ultraviolet, PBH evaporation will unavoidably lead to the production of these states. We illustrate this scenario by means of a simple toy model where PBH evaporation leads to the production of heavy particles that we call asymmetrons and whose decay results in a primordial charge asymmetry for right-handed electrons, which in turn sets the initial conditions for wash-in leptogenesis. We focus on the parameter region where the decay of the initial thermal asymmetron abundance occurs long before PBH evaporation and only results in a negligible primordial charge asymmetry. PBH evaporation at later times then serves as a mechanism to resurrect the asymmetron abundance and ensure the successful generation of the baryon asymmetry after all. We conclude that PBHs can act as asymmetry-producing machines that grant access to whatever CP-violating physics may be present in the ultraviolet, rekindling it at lower energies where it can be reprocessed into a baryon asymmetry by right-handed neutrinos.

Gravitational capture of magnetic monopoles by primordial black holes in the early universe

It is intriguing to ask whether the existence of primordial black holes (PBHs) in the early universe could significantly reduce the abundance of certain stable massive particles (SMP) via gravitational capture, after which the PBHs evaporate before BBN to avoid conflict with stringent bounds. For example, this mechanism is relevant to an alternative solution of the monopole problem proposed by Stojkovic and Freese, in which magnetic monopoles produced in the early universe are captured by PBHs, thus freeing inflation from having to occur during or after the corresponding phase transitions that produced the monopoles. In this work, we reanalyze the solution by modelling the capture process in the same way as the coexisting monopole annihilation. A subtle issue which is not handled properly in the previous literature is the choice of an effective capture cross section for diffusive capture. We model this aspect properly and justify our treatment. A monochromatic PBH mass function and a radiation-dominated era before PBH evaporation are assumed. We find that for Pati-Salam monopoles corresponding to a symmetry breaking scale between 1010 GeV and 1015 GeV, the capture rate is many orders of magnitude below what is needed to cause a significant reduction of the monopole density. Within our assumptions, we also find that the magnetic charge that is large enough to make an extremal magnetic black hole cosmologically stable cannot be obtained from magnetic charge fluctuation via monopole capture. The large magnetic charged required by cosmological stability can nevertheless be obtained from magnetic charge fluctuation at PBH formation, and if later the monopole abundance can be reduced significantly by some non-inflationary mechanism, long-lived near-extremal magnetic black holes of observational relevance might result.

511 keV line and primordial black holes from first-order phase transitions

511 keV gamma-ray excess from the Galactic center is a long lasting anomaly without satisfying astrophysical explanation. Hawking evaporation of hypothetical primordial black hole (PBH) with mass 1.0 × 10-17 ≲ M PBH/M ⊙ ≲ 8.0 × 10-17 and fractional abundance 10-3 ≲ f PBH ≲ 1.0, gives rise substantial non-relativistic electrons/positrons annihilating into diphoton, well reproduces the 511 keV line. However, it is obscure of the mechanism behind to form PBH with meteoritical mass in the early Universe. In this work, we investigated the production mechanism of PBHs through a cosmological first-order phase transition induced by quartic effective thermal potential via a scalar field in dark sector. We found the phase transition with vacuum energy, 𝒪(1) ≲ B 1/4/MeV ≲ 𝒪 (100), produces the desired monochromatic PBH mass and abundance fraction. Correlated signatures of gravitational wave and extragalactic gamma-ray, respectively coming from phase transition and black hole evaporation, are within μAres and AMEGO/e-ASTROGAM/COSI/XGIS-THESUS projected sensitivities. Finally, we include the PBH mass function from FOPT and found it can not improve the explanation to 511 keV excess.

Evaporation of primordial black holes in the early Universe: Mass and spin distributions

Evaporation of primordial black holes in the early Universe: Mass and spin distributions

Hawking Radiation and Lifetime of Primordial Black Holes in Braneworld

The paper explores the thermodynamic properties of primordial black holes (PBHs) in the braneworld. Specifically, the researchers examined Hawking radiation and the lifetime of PBHs. Through their analysis, an exact analytical expression for the Bekenstein–Hawking entropy, temperature, and heat capacity was derived. Their findings suggest that the lifetime of PBHs in the early universe is reduced by at least one order of magnitude, ultimately leading to their evaporation. This could explain why we have not observed the final rapid evaporation of PBHs in the recent epoch of the universe.

Distinct signatures of spinning PBH domination and evaporation: doubly peaked gravitational waves, dark relics and CMB complementarity

Ultra-low mass primordial black holes (PBH), which may briefly dominate the energy density of the universe but completely evaporate before the big bang nucleosynthesis (BBN), can lead to interesting observable signatures. In our previous work, we studied the generation of a doubly peaked spectrum of induced stochastic gravitational wave background (ISGWB) for such a scenario and explored the possibility of probing a class of baryogenesis models wherein the emission of massive unstable particles from the PBH evaporation and their subsequent decay contributes to the matter-antimatter asymmetry. In this work, we extend the scope of our earlier work by including spinning PBHs and consider the emission of light relativistic dark sector particles, which contribute to the dark radiation (DR) and massive stable dark sector particles, thereby accounting for the dark matter (DM) component of the universe. The ISGWB can probe the non-thermal production of these heavy DM particles, which cannot be accessible in laboratory searches. For the case of DR, we find a novel complementarity between the measurements of ∆Neff from these emitted particles and the ISGWB from PBH domination. Our results indicate that the ISGWB has a weak dependence on the initial PBH spin. However, for gravitons as the DR particles, the initial PBH spin plays a significant role, and only above a critical value of the initial spin parameter a*, which depends only on initial PBH mass, the graviton emission can be probed in the CMB-HD experiment. Upcoming CMB experiments such as CMB-HD and CMB-Bharat, together with future GW detectors like LISA and ET, open up an exciting possibility of constraining the PBHs parameter space providing deeper insights into the expansion history of the universe between the end of inflation and BBN.

Gravitational wave signatures of a PBH-generated baryon-dark matter coincidence

We propose a new way of probing non-thermal origin of baryon asymmetry of universe (BAU) and dark matter (DM) from evaporating primordial black holes (PBH) via stochastic gravitational waves (GW) emitted due to PBH density fluctuations. We adopt a baryogenesis setup where CP violating out-of-equilibrium decays of a coloured scalar, produced non-thermally at late epochs from PBH evaporation, lead to the generation of BAU. The same PBH evaporation is also responsible for non-thermal origin of superheavy DM. Unlike the case of baryogenesis {\it via leptogeneis} that necessarily corners the PBH mass to $\sim\mathcal{O}(1)$ g, here we can have PBH mass as large as $\sim\mathcal{O}(10^7)$ g due to the possibility of producing BAU directly below sphaleron decoupling temperature. Due to the larger allowed PBH mass we can also have observable GW with mHz-kHz frequencies originating from PBH density fluctuations keeping the model constrained and verifiable at ongoing as well as near future GW experiments like LIGO, BBO, DECIGO, CE, ET etc. Due to the presence of new coloured particles and baryon number violation, the model also has complementary detection prospects at laboratory experiments.

Updated constraints on primordial black hole evaporation

The Hawking evaporation process, leading to the production of detectable particle species, constrains the abundance of light black holes, presumably of primordial origin. Here, we reconsider and correct constraints from soft gamma-ray observations, including of the gamma-ray line, at 511 keV, produced by electron-positron pair-annihilation, where positrons originate from black hole evaporation. First, we point out that the INTEGRAL detection of the Large Magellanic Cloud provides one of the strongest bounds attainable with present observations; and that future MeV gamma-ray telescopes, such as GECCO, will greatly enhance such constraints. Second, we discuss issues with previous limits from the isotropic flux at 511 keV and we provide updated, robust constraints from recent measurements of the diffuse Galactic soft gamma-ray emission and from the isotropic soft gamma-ray background.

New accretion constraint on the evaporation of primordial black holes

New accretion constraint on the evaporation of primordial black holes

A new constraint on the Hawking evaporation of primordial black holes in the radiation-dominated era

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}g rather than 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.

Search for the evaporation of primordial black holes with H.E.S.S.

Primordial Black Holes (PBHs) are hypothetical black holes predicted to have been formed from density fluctuations in the early Universe. PBHs with an initial mass around 1014–1015 g are expected to end their evaporation at present times in a burst of particles and very-high-energy (VHE) gamma rays. Those gamma rays may be detectable by the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric Cherenkov telescopes. This paper reports on the search for evaporation bursts of VHE gamma rays with H.E.S.S., ranging from 10 to 120 seconds, as expected from the final stage of PBH evaporation and using a total of 4816 hours of observations. The most constraining upper limit on the burst rate of local PBHs is 2000 pc-3 yr-1 for a burst interval of 120 seconds, at the 95% confidence level. The implication of these measurements for PBH dark matter are also discussed.

Dark matter prospects with COSI: ALPs, PBHs and sub-GeV dark matter

We study the prospects in the search of dark matter offered by the newly selected NASA MeV mission COSI (Compton Spectrometer and Imager). This instrument is designed and optimized to detect spectral lines, and we show it offers an exquisite possibility to detect dark matter directly decaying or annihilating into monochromatic gamma-rays. This is the case, for example, for axion-like particles (ALPs) which undergo decay into two photons. Furthermore, we show that COSI can lead to important progress in the quest for primordial black holes (PBHs) dark matter, through measurements of the 511 keV line from the positrons produced via Hawking evaporation.We also outline opportunities for the search of continuum signals, such as those expected from sub-GeV dark matter annihilation/decay into leptons and PBH evaporation into photons. We find that also in this case COSI can lead to improvements of current bounds.

Signatures from primordial black hole evaporation

Primordial Black Holes are hypothetical Black Holes formed in the very early universe and are potential Dark Matter Candidates. We focus on the primordial black hole mass range [5 · 1014 − 1 · 1016] g. Their evaporation can produce detectable signals in existing experiments. We study neutrinos emitted by PBHs evaporation. The interaction of neutrinos emitted from primordial black hole evaporation can interact through the coherent elastic neutrino-nucleus scattering producing an observable signal in multi-ton DM direct detection experiments. The non-observation of such signals can be used to place forecast constraints on the fraction of Dark Matter composed of Primordial Black Holes. This talk is based on [1]

Primordial Black Holes as dark matter candidates: Constraints from the diffuse MeV emission

For more than 20 years, the Compton telescope had provided the best measurements of the Galactic diffuse MeV spectrum. Recently, our analysis of 16 years of data from the SPectrometer on INTEGRAL (SPI) measured this emission with a higher signal-to-noise ratio. At MeV energies, the dominant contribution to the diffuse emission comes from inverse Compton scattering. Nonetheless, sub-dominant emission from Primordial Black Hole (PBH) Dark Matter (DM) can be searched for in these data. Hypothetically formed from the collapse of over-densities before Big Bang nucleosynthesis, PBHs are interesting candidates for DM in the ΛCDM model of cosmology. PBHs of masses between 1016 and 1018 g, in the so-called asteroid mass range, are currently unconstrained and can saturate the DM cosmological abundance. MeV emission from PBH in this mass range is expected to come from PBH evaporation. We searched for the PBH signal with 16 years of SPI data, and demonstrated that PBHs cannot account for all the DM if their mass is smaller than 4 × 1017 g.

The interplay between the dark matter axion and primordial black holes

If primordial black holes (PBHs) had come to dominate the energy density of the early Universe when oscillations in the axion field began, we show that the relic abundance and expected mass range of the QCD axion would be greatly modified. Since the QCD axion is a potential candidate for dark matter (DM), we refer to it as the DM axion. We predominantly explore PBHs in the mass range (106 - 5× 108)g. We investigate the relation between the relic abundance of DM axions and the parameter space of PBHs. We numerically solve the set of Boltzmann equations, that governs the cosmological evolution during both radiation and PBH-dominated epochs, providing the bulk energy content of the early Universe. We further solve the equation of motion of the DM axion field to obtain its present abundance. Alongside non-relativistic production mechanisms, light QCD axions are generated from evaporating PBHs through the Hawking mechanism and could make up a fraction of the dark radiation (DR). If the QCD axion is ever discovered, it will give us insight into the early Universe and probe into the physics of the PBH-dominated era. We estimate the bounds on the model from DR axions produced via PBH evaporation and thermal decoupling, and we account for isocurvature bounds for the period of inflation where the Peccei-Quinn symmetry is broken. We assess the results obtained against the available CMB data and we comment on the forecasts from gravitational wave searches. We briefly state the consequences of PBH accretion and the uncertainties this may further add to cosmology and astroparticle physics modeling.

Axionlike particles from primordial black hole evaporation and their detection in neutrino experiments

The primordial black holes (PBHs) play as a novel source to radiate light elementary particles of energies in the region of a few hundred MeV. We explore the possibility that the axion-like particles (ALPs) with mass less than 1 MeV are produced from PBH evaporation. The absorption of light ALPs in the underground detector targets then induces energetic photoelectron signatures in current and future neutrino experiments. Utilizing the PBH ALP event rate, we place general exclusion limits on the axion couplings at Super-K and Hyper-K. We also translate these limits into the upper bound on the fraction of DM composed of PBHs $f_{\rm PBH}$.

Primordial black holes having gravitomagnetic monopole

A primordial black hole (PBH) is thought to be made of the regular matter or ordinary mass ($M$) only, and hence could have already been decayed due to the Hawking radiation if its initial ordinary mass were $\lesssim 5 \times 10^{11}$ kg. Here, we study the role of gravitomagnetic monopole for the evaporation of PBHs, and propose that the lower energy PBHs (equivalent to ordinary mass $M << 5\times 10^{11}$ kg) could still exist in our present Universe, if it has gravitomagnetic monopole. If a PBH was initially made of both regular matter and gravitomagnetic monopole, the regular matter could decay away due to the Hawking radiation. The remnant gravitomagnetic monopole might not entirely decay, which could still be found as a PBH in the form of the pseudo `mass-energy'. If a PBH with $M \gtrsim 5 \times 10^{11}$ kg is detected, one may not be able to conclude if it has gravitomagnetic monopole. But, a plausible detection of a relatively low energy (equivalent to $2.176 \times 10^{-8}$ kg $< M \lesssim 5\times10^{11}$ kg) PBH in future may imply the existence of a gravitomagnetic monopole PBH, which may or may not contain the ordinary mass.