Universe, Volume 10, Issue 12

In the initial part of this paper, we survey (in arbitrary spacetime dimension) the general FLRW cosmologies with non-interacting perfect fluids and with a canonical or phantom scalar field, minimally coupled to gravity and possibly self-interacting;...

This Special Issue is dedicated to photons of energies above 10¹⁸ eV, i [...]

In the early stages of planetary system formation, young exoplanets gravitationally interact with their surrounding environments and leave observable signatures on protoplanetary disks. Among these structures, a pair of nearly symmetric spiral arms c...

The motion of gravitational axion-like particles (ALPs) around a Kerr black hole is analyzed, paying attention to the resonance and distribution of spectral radiation. We first discuss the computation of $\sqrt{g}{\tilde{R}}_{\mu \nu \rho \rho \sigma }{R}^{\mu \nu \mathrm{\&rh}}$...

The current accelerated expansion of the Universe remains one of the most intriguing topics in modern cosmology, driving the search for innovative statistical techniques. Recent advancements in machine learning have significantly enhanced its applica...

Different sulfates (Ca-, Mg, and Fe- sulfates) have been extensively detected on the Martian surface. As one of the Martian sulfates, the presence of ferrous sulfates will provide valuable clues about the redox environment, hydrological processes, an...

We present some addition theorems for spin-weighted spherical harmonics, generalizing previous results for scalar (spin-zero) spherical harmonics. These addition theorems involve sums over the azimuthal quantum number of products of two spin-weighted...

We present a theoretical analysis of the experimental data reported by Ichikawa et al. on the spatial distribution of ultracold neutrons in the Earth’s gravitational field above a mirror. The data involve a projection onto a pixelated detector...

We compute the evolution of linear perturbations on top of a background solution of a general nonlinear electromagnetic theory. This evolution can be described in terms of two effective metrics, and we analyze under what conditions they are conformal...

In comparing the two alternative explosion mechanisms of core-collapse supernovae (CCSNe), I examine recent three-dimensional (3D) hydrodynamical simulations of CCSNe in the frame of the delayed neutrino explosion mechanism (neutrino mechanism) and a...

The long-distance and non-local parts of the form factors describing the single-photon-mediated $K_{S,L}\to {\pi }^0{\gamma }^{*}\to {\pi }^0{\mathsf{\ell }}^{+}{\mathsf{\ell }}^{-}$ ($\mathsf{\ell }=e,\mu$) transitions in the standard model are addressed in QCD regarding the limit where...

We calculated the two-loop corrections in the primordial power spectrum in models of single-field inflation incorporating an intermediate USR phase employed for PBH formation. Among the overall eleven one-particle irreducible Feynman diagrams, we cal...

With the release of Gaia DR3, evaluating the performance and consistency of its reference frame (Gaia-CRF3) with the International Celestial Reference Frame (ICRF3) has become a critical task. Gaia-CRF3 serves as the second non-rotating inertial refe...

In this work, we investigate spacetime and photon dynamics around a charged Hayward black hole, focusing on the effects of electric charge Q and the length factor l. Our analysis shows that the maximum charge for black hole existence decreases as l i...

Accreting X-ray pulsars, located in X-ray binaries, are neutron stars with magnetic fields as strong as $B\sim {10}^{12–13}$ G. This review offers a concise overview of the accretion and radiation processes of X-ray pulsars and summarizes their rich o...

The quantum electromagnetic (EM) field is formulated in the Weyl–Wigner representation (WW), which is equivalent to the standard Hilbert space one (HS). In principle, it is possible to interpret within WW all experiments involving the EM field...

This is a tutorial on the strong gravity effects (motion of massive and massless particles in a curved spacetime, evaluation of redshift factors, estimate of physical quantities in different reference frames, etc.) necessary to calculate the electrom...

The Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) faces challenges in establishing high-precision rigid connections between the receiver and the reflective surface due to its vast spatial span. Innovatively, FAST suspends the feed cabi...

The recent astrometric data of hundreds of millions of stars from Gaia DR3 has allowed for a precise determination of the Milky Way rotation curve up to 28 kpc. The data suggest a rapid decline in the density of dark matter beyond 19 kpc. We fit the...

Wigner’s classification has led to the insight that projective unitary representations play a prominent role in quantum mechanics. The physics literature often states that the theory of projective unitary representations can be reduced to the t...

Let two test particles A and B, revolving about a spinning primary along ideally identical orbits in opposite directions, be considered. From the general expressions of the precessions of the orbital inclination induced by the post-Newtonian gravitom...

In the case of low-mass X-ray binaries, the companion star is often too faint for detection; therefore, there is no chance for dynamical studies to independently determine the mass of the compact object. In the absence of a mass estimate, one cannot...

Magnetohydrodynamic (MHD) numerical simulation has emerged as a pivotal tool in space physics research, witnessing significant advancements. This methodology offers invaluable insights into diverse space physical phenomena based on solving the fundam...

Primordial black holes (PBHs) may have formed through the gravitational collapse of cosmological perturbations that were generated and stretched during the inflationary era, later entering the cosmological horizon during the decelerating phase, if th...

In the context of chameleon gravity, we present a semi-analytical solution of the chameleon field profile in an accurately modelled galaxy cluster’s mass components, namely the stellar mass of the Brightest Cluster Galaxy (BCG), the baryonic ma...

We reexamine the angular correlation between the emitted electrons in the double beta decay (DBD) of ¹⁰⁰Mo, with particular attention to the impact of electronic wave function phase shifts. In the two-neutrino mode, the angular correlation factor inc...

A variety of high-energy events can take place in the seconds leading up to a binary neutron star merger. Mechanisms involving tidal resonances, electrodynamic interactions, or shocks in mass-loaded wakes have been proposed as instigators of these pr...

Solar radio spectral observation is one of the essential approaches for solar physics research, which helps us study the plasma dynamics in the solar atmosphere. The Solar Broadband Radio Dynamic Spectrometer (SBRS) started observing the Sun at Huair...

We investigate the statistics of the available Pantheon+ dataset. Noticing that the ${\chi }^2$ value for the best-fit $\Lambda$CDM model to the real data is small, we quantify how significant its smallness is by calculating the distribution of ${\chi }^2$ valu...

Jet precession is thought to be a ubiquitous phenomenon in astronomical events of various scales, including gamma-ray bursts (GRBs). If GRB jets undergo precession, periodic features might be introduced into their light curves. Detecting these period...

The locations of hot pulsating variables in the H–R diagram are found using the effective temperatures derived from spectroscopic analysis and luminosities from Gaia parallaxes. Frequency peaks extracted from TESS photometry were used to compar...

We investigate the reliability of the conservation of the vector current (CVC) hypothesis in the neutron beta decay (n ${\beta }^{-}$ decay). We calculate the contribution of the phenomenological term, responsible for the CVC in the hadronic curr...

Supermassive black holes (SMBHs) are observed in active galactic nuclei interacting with their environments, where chaotical, discontinuous accretion episodes may leave matter remnants orbiting the central attractor in the form of sequences of orbiti...

Active galactic nuclei (AGNs) exhibit significant luminosity variations across the entire electromagnetic spectrum, with timescales ranging from hours to years. Studying the optical variability of AGNs provides crucial insights into their physical pr...