Universe, Volume 8, Issue 4

The afterglow data of gamma ray bursts (GRBs) can be used to constrain the physical properties of the fireball (e.g., the jet structure and opening angle) and the circumburst medium. With the peak time of the early afterglow light curve being taken a...

We show that a Minkowski phase space endowed with a bracket relatively to a conformable differential realizes a Poisson algebra, confering a bi-Hamiltonian structure to the resulting manifold. We infer that the related Hamiltonian vector field is an...

We propose the generalized multipomeron exchange model for multiparticle production in high-energy proton–proton, proton–nucleus and heavy-ion collisions. For all of these systems, we consider collectivity effects based on the quark&ndash...

Maxwell’s vacuum equations are integrated for admissible electromagnetic fields in homogeneous spaces. Admissible electromagnetic fields are those for which the space group generates an algebra of symmetry operators (integrals of motion) that i...

Recently, several methods have been proposed to regularize a $D\to 4$ limit of Einstein–Gauss–Bonnet (EGB), leading to nontrivial gravitational dynamics in $4D$. We present an exact nonsingular black hole solution in the $4D$ EGB gravity coup...

The initial mass-final mass relationship (IFMR) of white dwarfs (WD) represents a crucial benchmark for stellar evolution models, especially for the efficiency of mixing episodes and mass loss during the asymptotic giant branch (AGB) phase. In this s...

It is well known that extraordinary photons in hyperbolic metamaterials may be described as living in an effective Minkowski spacetime, which is defined by the peculiar form of the strongly anisotropic dielectric tensor in these metamaterials. Here,...

We present a miniaturized and wide field-of-view X-ray and Gamma-ray imager consisting of a segmented 2D optics-collimator coupled to the high-sensitivity semiconductor pixel detector Timepix equipped with a high-Z sensor (CdTe 2000 $\mathsf{\mu }$m thick). The...

The standard formulation of general relativity fails to describe some recent interests in the universe. It impels us to go beyond the standard formulation of gravity. The $f\left(Q\right)$ gravity theory is an interesting modified theory of gravity, where the gra...

This Special Issue collects articles devoted to various aspects of astrophysics which can be understood as a science investigating stars, galaxies, their types and properties, stages of their evolution, distribution in the Universe and the interstell...

The ${\nu }_{\mu }\to {\nu }_e$ oscillation probability over a short baseline (≲1 km) would be negligible for the case when the mixing matrix for three active neutrinos is unitary. However, in the case of a non-unitary mixing of three neutrinos, this p...

The vacuum transition probabilities for a Friedmann–Lemaître–Robertson–Walker universe with positive curvature in Hořava–Lifshitz gravity in the presence of a scalar field potential in the Wentzel–Kramers&ndas...

Using observations by the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument on board the TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) satellite and simulations by the TIEGCM (Thermosphere-Ionosphe...

We analyse the dark Higgs inflation model with curvature corrections and explore the possibility to test its predictions by the particle physics experiments at LHC. We show that the dark Higgs inflation model with curvature corrections is strongly fa...

Electroweak baryogenesis can be driven by the top quark in a general two Higgs doublet model with extra Yukawa couplings. Higgs quartics provide the first order phase transition, while extra top Yukawa coupling ${\rho }_{tt}$ can fuel the cosmic baryon asym...

The chemical evolution of galaxies is governed by the chemical yields from stars, and here we focus on the important contributions from asymptotic giant branch (AGB) stars. AGB nucleosynthesis is, however, still riddled with complexities. Observation...

We obtain exact Bardeen black holes to the regularized $4D$ Einstein–Gauss–Bonnet (EGB) gravity minimally coupled with the nonlinear electrodynamics (NED). In turn, we analyze the horizon structure to determine the effect of GB parameter $\mathrm{\&a}$...

Using a paraboloid model of an Earth-like exoplanetary magnetospheric magnetic field, developed from a model of the Earth, we investigate the magnetospheric structure of planets located in the habitable zone around G-type stars. Different directions...

We propose a generalization of the external direct product concept to polyadic algebraic structures which introduces novel properties in two ways: the arity of the product can differ from that of the constituents, and the elements from different mult...

We present and discuss well known conditions for ultraviolet finiteness and asymptotic safety. The requirements for complete absence of ultraviolet divergences in quantum field theories and existence of a non-trivial fixed point for renormalization g...

Using a phenomenological Ginzburg–Landau model that includes entrainment, we identify the possible ground states for the neutron and proton condensates in the core of a neutron star, as a function of magnetic field strength. Combining analytica...

Lepton-flavor violation (LFV) has been discovered in the neutrino sector by neutrino oscillation experiments. The minimal extension of the Standard Model (SM) to include neutrino masses allows LFV in the charged sector (CLFV) at the loop level, but a...

An accurate understanding of dissimilarities in geomagnetic variability between quiet and disturbed periods has the potential to vastly improve space weather diagnosis. In this work, we exploit some recently developed methods of dynamical system theo...

A method for consistent quantization of conformal gravity treating conformal symmetry in a very controllable way is presented. First, we discuss local conformal symmetry in the framework of gravitational interactions, where we view it as an example o...

Scattered radiation of circumstellar (CS) dust plays an important role in the physics of young stars. Its observational manifestations are various but more often they are connected with the appearance of intrinsic polarization in young stars and thei...

We discuss an approach to the problem of calculating the local topological index of vector fields given on complex spaces or varieties with singularities developed by the author over the past few years. Our method is based on the study of the homolog...

We show that an $L_{\infty }$-algebra can be extended to a graded Hopf algebra with a codifferential. Then, we twist this extended $L_{\infty }$-algebra with a Drinfel’d twist, simultaneously twisting its modules. Taking the $L_{\infty }$-algebra as its own (...

Several hundred gamma-ray burst (GRB) redshifts have been determined to date. One of the other important properties—besides the distance—of the GRBs is the duration of the burst. In this paper, we analyse these two important quantities of...

The foundations of stellar nucleosynthesis have been established more than 70 years ago. Since then, much progress has been made, both on the theoretical side, with stellar evolution and nucleosynthesis models of increasing complexity, using more and...

In the past three decades, the ground-based technique of imaging atmospheric Cherenkov telescopes has established itself as a powerful discipline in science. Approximately 250 sources of very high gamma rays of both galactic and extra-galactic origin...

The possibility of radiation of high-energy gamma quanta with energies of the order of 100 GeV by ultrarelativistic electrons on nuclei in strong X-ray fields with intensities up to ∼10${}^{27}{\mathrm{Wcm}}^{-2}$ was theoretically studied. It is shown that thi...

Clarifying the nature of the quantum state $|\mathsf{\Psi }⟩$ is at the root of the problems with insight into counter-intuitive quantum postulates. We provide a direct—and math-axiom free—empirical derivation of this object as an element of...

In the 21th century astronomical observations, as well as astrophysical models, have become impressively precise. For a better understanding of the processes in stellar interiors, the nuclear physics of astrophysical relevance—known as nuclear...

In this review, we revisit our latest works regarding the description of the gravitational interaction on noncommutative spaces as matrix models. Specifically, inspired by the gauge-theoretic approach of (ordinary) gravity, we make use of the suggest...

We do not have a final answer to the question of why galaxies choose a particular internal mass distribution. Here we examine whether the distribution is set by thermodynamic equilibrium (TE). Traditionally, TE is discarded for a number of reasons in...

We present a summary of the main results within the Scale Invariant Vacuum (SIV) paradigm as related to the Weyl Integrable Geometry (WIG) as an extension to the standard Einstein General Relativity (EGR). After a brief review of the mathematical fra...

WASP-12b stands out among the planets of its class of hot Jupiters because of the observed fast orbital decay attributed to tidal dissipation. The measured rate of the orbital period change is ${\stackrel{\cdot }{P}}_{\mathrm{orb}}=-29\pm 3\mathrm{ms}/\mathrm{yr}$= $-(9.2\pm 1.$...

In this paper, we focus on the relation between quasinormal modes (QNMs) and a rotating black hole shadow. As a specific example, we consider the quantum deformed Kerr black hole obtained via Newman–Janis–Azreg-Aïnou algorithm. In pa...

The presence of dust in the intracluster medium (ICM) has been a long-standing problem that is still awaiting elucidation. Direct observational diagnostics are rather challenging (though not impossible) either because of a sparse distribution of dust...

Spin foam theory is a concrete framework for quantum gravity where numerical calculations of transition amplitudes are possible. Recently, the field became very active, but the entry barrier is steep, mainly because of its unusual language and notion...

The Kelvin–Helmholtz (KH) instability, a common phenomenon widely observed at the magnetopause, plays an important role in plasma transport while reconnection at low latitude is less efficient during the northward interplanetary magnetic field...

Based on the concept of ontological states and their dynamical evolution by permutations, as assumed in the Cellular Automaton Interpretation (CAI) of quantum mechanics, we address the issue of whether quantum-classical hybrids can be described consi...

RR Lyrae stars are recognized as some of the oldest stars in the Universe. In addition, they are some of the few old celestial objects for which distances can be reliably inferred. As such, these stars are excellent tracers of the oldest structures t...

We explore the behaviour of barotropic and irrotational fluids with a small viscosity under the effect of first-order acoustic perturbations. We discuss, following the extant literature, the difficulties in gleaning an acoustic geometry in the presen...

Regular black holes represent a conservative model in which the classical singularity is replaced by a non-singular core without necessarily modifying the spacetime outside the trapping horizon. Given the possible lack of phenomenological signatures,...

The mean anomaly at epoch $\eta$ is one of the standard six Keplerian orbital elements in terms of which the motion of the two-body problem is parameterized. Along with the argument of pericenter $\omega$, $\eta$ experiences long-term rates of change in...

We study neutrino propagation in a curved spacetime background described by the Schwarzschild solution with the addition of quantum corrections evaluated in the framework of perturbative quantum gravity at lowest order. In particular, we investigate...

Cosmological models with variable and modified equations of state for dark energy are confronted with observational data, including Type Ia supernovae, Hubble parameter data $H\left(z\right)$ from different sources, and observational manifestations of cosmic micr...

We introduce T-duality invariant versions of D-branes in doubled geometry using a global covariant framework based on para-Hermitian geometry and metric algebroids. We define D-branes as conformal boundary conditions for the open string version of th...

We consider a multi-scalar field model in the Jordan frame, which can be seen as a two-scalar field model where the Brans–Dicke field interacts in the kinetic part with the second scalar field. This theory under a conformal transformation reduc...