Antistars in the Galaxy
Possible existence of antimatter in our Galaxy, in particular of antistars is discussed and the mechanism of their creation is described.
astro-ph.CO↗
arXiv subjects
A. D. Dolgov
Publications and source records attributed to A. D. Dolgov.
Antimatter in the Milky Way
Recent astronomical observations indicating a strikingly abundant presence of antimatter in the Galaxy, in particular, of anti-stars are reviewed. Long-time earlier theoretical predictions are briefly discussed.
astro-ph.GA↗
Asymmetric baryon capture by primordial black holes and baryon asymmetry of the universe
We have refined our previously suggested scenario of generation of the cosmological baryon asymmetry through an asymmetric capture of baryons and antibaryons by primordial block hole arXiv:2009.04361. It is found that in the limit of weak interactions of hypothetical heavy baryons with the primeval plasma the effect can be strongly enhanced and the observed magnitude of the asymmetry can be obtained for a wide range of the model parameters.
hep-ph↗
Primordial Black holes and Modification of Zeldovich-Novikov Mechanism
Bulk of various astronomical observations of black holes suggest that virtually all observed black holes can be of primordial origin. A modified mechanism of the primordial black hole formation is described. A universal log-normal mass spectrum with a mean mass of around $\sim 10 M_\odot$ predicted by this mechanism is strongly confirmed by the LIGO/Virgo observations of gravitational waves from coalescing binary black holes.
astro-ph.CO↗
Primordial Black Holes Around Us Now, Long Before, and Far away
Recent astronomical data on Black hole observations are reviewed. The arguments in favor that the observed black holes are predominantly primordial (PBH) are presented. The mass spectrum of PBH is best fit to the log-normal one. A model of PBH formation with log-normal spectrum is briefly described.
astro-ph.CO↗
On mass distribution of coalescing black holes
Available data on the chirp mass distribution of the coalescing black hole binaries in O1-O3 LIGO/Virgo runs are analyzed and compared statistically with the distribution calculated under the assumption that these black holes are primordial with a log-normal mass spectrum. The theoretically calculated chirp mass distribution with the inferred best acceptable mass spectrum parameters, $M_0=17 M_\odot$ and $γ=0.9$, perfectly describes the data. The value of $M_0$ very well agrees with the theoretically expected one. On the opposite, the chirp mass distribution of black hole binaries originated from massive binary star evolution requires additional model adjustments to reproduce the observed chirp mass distribution
astro-ph.CO↗
Baryogenesis through baryon capture by black holes
A novel mechanism of cosmological baryogenesis through baryon capture by primordial black holes is suggested. In contrast to the conventional scenarios it does not demand non-conservation of baryonic number in particle physics and can proceed in thermal equilibrium. For implementation of this mechanism a heavy superweakly interacting particle a with non-zero baryon number is necessary.
hep-ph↗
Superheavy dark matter in $R+R^2$ cosmology with conformal anomaly
Cosmological evolution and particle creation in $R^2$-modified gravity are considered for the case of the dominant decay of the scalaron into a pair of gauge bosons due to conformal anomaly. It is shown that in the process of thermalization superheavy dark matter with the coupling strength typical for the GUT SUSY can be created. Such dark matter would have the proper cosmological density if the particle mass is close to $10^{12}$ GeV.
hep-ph↗
Massive photons and electrically charged black holes
The characteristic time of disappearance of electric field in massive electrodynamics during the capture of electric charge by black holes is calculated. It is shown that this time does not depend upon the photon mass. The electric field at large distances disappears with the speed of light.
gr-qc↗
Massive primordial black holes in contemporary universe
The parameters of the original log-normal mass spectrum of primordial black holes (PBH) are approximately adjusted on the basis of existing observational data on supermassive black holes in the galactic centers and the mass distribution of the near-solar mass black holes in the Galaxy. Together with the assumption that PBHs make all or a noticeable mass fraction of the cosmological dark matter, it allows to fix the parameters of the original mass spectrum. The predicted, in this way, the number density of MACHOs is found to be about an order of magnitude below the observed value. A possible resolution of this controversy may be prescribed to the non-isotropic and inhomogeneous distribution of MACHOs or to the modification of the original spectrum, e.g. assuming a superposition of two-maximum log-normal spectra of PBHs. A competing possibility is that MACHOs are not PBHs but dead primordial compact stars.
astro-ph.CO↗
Electromagnetic phenomena around black holes
Transition of gravitational waves, produced in the process of coalescence of black hole binaries, into electromagnetic radiation in magnetic field is discussed. The magnetic field is assumed to be created by rotating electrically charged black holes. The process of electric charging of black holes due to different mobilities of protons and electrons in the surrounding plasma is described.
gr-qc↗
New data on young and old black holes and other unexpected creatures
A review on recent astronomical observations indicating to unexpectedly abundant population of the contemporary and $ z \sim 10 $ universe by massive black holes in all mass ranges are is presented. It is argued that these black holes are mostly primordial. The data on some other stellar-kind objects which are also may be primordial are discussed.
astro-ph.GA↗
Massive Primordial Black Holes
A review of the astronomical data of several last years on an astonishingly high amount of black holes in the contemporary and early ($z\sim 10$) universe is presented. Also the data on the recently observed peculiar stars in the Galaxy are discussed. It is argued that practically all black holes in the universe are primordial (PBH) and suggested that an inverted picture of the galaxy formation is realized: supermassive black holes were formed prior to galaxy formation and subsequently seeded the latter. Possibilities of cosmological dark matter consisting of primordial black holes and of abundant cosmological antimatter are considered. A mechanism of 1993 anticipating all these phenomena and predicting an extended log-normal mass spectrum of PBH is described.
astro-ph.CO↗
Dark matter in $R+R^2$ cosmology
Production of massive stable relics in $R^2$-modified gravity is considered. It is shown that the cosmological evolution and kinetics of massive species differs significantly from those in the conventional cosmology. The results are applied to the lightest supersymmetric particles and it is argued that they are viable candidates for the constituents of dark matter, if their mass is about 1000 TeV.
astro-ph.CO↗
Distortion of the standard cosmology in R+R^2 theory
Universe history in $R^2$-gravity is studied from "beginning" up to the present epoch. It is assumed that initially the curvature scalar $R$ was sufficiently large to induce the proper duration of inflation. Gravitational particle production by the oscillating $R(t)$ led to a graceful exit from inflation, but the cosmological evolution in the early universe was drastically different from the standard one till the universe age reached the value of the order of the inverse decay rate of the oscillating curvature $R(t)$. This deviation from the standard cosmology might have a noticeable impact on the formation of primordial black holes and baryogenesis. At later time, after exponential decay of the curvature oscillations, cosmology may return to normality.
gr-qc↗
Massive Primordial Black Holes in Contemporary and Young Universe (old predictions and new data)
A brief review of the recent astronomical data, indicating that the universe is abundantly populated by heavy black holes (BH), is presented. Conventional astrophysics and cosmology cannot explain such a high population of BHs. A mechanism of the paper of 1963 is described, which at least qualitatively explained the observational data. In particular, the prediction that massive primordial BHs can be cosmological dark matter "particles" is discussed.
astro-ph.CO↗
Evolution of thick domain walls in inflationary and $p=wρ$ universe
We study the evolution of thick domain walls in the different models of cosmological inflation, in the matter-dominated and radiation-dominated universe, or more generally in the universe with the equation of state $p=wρ$. We have found that the domain wall evolution crucially depends on the time-dependent parameter $C(t)=1/(H(t)δ_0)^2$, where $H(t)$ is the Hubble parameter and $δ_0$ is the thickness of the wall in flat space-time. For $C(t)>2$ the physical thickness of the wall, $a(t)δ(t)$, tends with time to $δ_0$, which is microscopically small. Otherwise, when $C(t) \leq 2$, the wall steadily expands and can grow up to a cosmologically large size.
gr-qc↗
Science with e-ASTROGAM (A space mission for MeV-GeV gamma-ray astrophysics)
e-ASTROGAM (enhanced ASTROGAM) is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV - the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA.
astro-ph.HE↗