Universe

Using an open thermodynamic systems theory, the effect of particle creation on the evolution and dynamics of the standard cosmological FLRW model in a higher-dimensional spacetime with functionally dependent cosmological and gravitational constants $\mathsf{\Lambda }$ and G is investigated. The gravitational field equations have been transformed into a dimensionless system of non-linear, first-order, coupled differential equations (DEs) as functions of the universe’s density parameters ${\Omega }_i$ and rate of particle creation $\mathsf{\Psi }$ in redshift space, which can be numerically casted. Two cosmological models are obtained, depending on the choice of particle creation rate—$\mathsf{\Psi }\sim H^2$ and $\mathsf{\Psi }\sim n^2$ for dust-, radiation- and dark-energy-dominated universes, respectively. The dynamic behaviour of each model is discussed. Full article

We consider the central configurations of the $1+N$-body problem, where N bodies are infinitesimal and the remaining one body is dominant. For regular polygon central configurations, we prove that the masses of all the infinitesimal bodies are equal when N is odd and the masses of the alternate infinitesimal bodies must be equal when N is even. Moreover, in the case of N being even, we present the relationship of the mass parameters between two consecutive infinitesimal bodies. Full article

Taking the generalized uncertainty principle (GUP) into account, we apply the corrected state density to investigate the entropy density, energy density, pressure and equation of state for the perfect relativistic gases of massless particles with an arbitrary spin of s ≤ 2 surrounding a new four-dimensional neutral Gauss–Bonnet black hole. The modifications of these thermodynamic quantities by the gravity correction factor and particle spin are shown, and the expressions have completely different forms from those in flat space-times. For example, the energy density is not proportional to the fourth power of the temperature. In other words, the energy density differs from that of blackbody radiation. The quantum gravity effects reduce these quantities and are proportional to the gravity correction factor. The result that the equation of state is not zero is compatible with the non-vanishing trace of the stress tensor. Full article

Oort constants and local kinematics are vital parameters with which to study the structure and dynamics of the Milky Way. When GCNS was published, it provided a clean sample of stars in the solar vicinity, which gives us an ideal tool with which to determine these parameters. Our aim was to calculate the reliable Oort constants with GCNS. We determined the Oort constants using the GCNS from Gaia EDR3 with $d<100$$\mathrm{pc}$. The proper motions and radial velocities were fitted with a maximum likelihood model. The uncertainties were obtained with an MCMC method. The sample was carefully selected to obtain a reliable result. The result yields the Oort constants $A=15.6\pm 1.6\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$, $B=-15.8\pm 1.7\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$, $C=-3.5\pm 1.6\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$, and $K=2.7\pm 1.5\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$. The non-zero C and K imply that the local disc is in a non-asymmetric potential. With the Oort constants, we derived the local angular velocity ${\Omega }_0\approx A-B=31.4\pm 2.3\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-1}$. The solar motion ($U_{\odot }$, $V_{\odot }$, $W_{\odot }$) was calculated as ($10.1\pm 0.1$, $22.8\pm 0.1$, $7.8\pm 0.1$) $\mathrm{km}{\mathrm{s}}^{-1}$. Full article

Fast Radio Bursts (FRBs) are millisecond-duration transient events that are typically observed at radio wavelengths and cosmological distances but their origin remains unclear. Furthermore, most FRB origin models are related to the processes at stellar scales, involving neutron stars, blackholes, supernovae, etc. In this paper, our purpose is to determine whether multi-structural one-off FRBs and repeaters share similarities. To achieve this, we focus on analyzing the relationship between the FRB event rate and the star formation rate, complemented by statistical testing methods. Based on the CHIME/FRB Catalog 1, we calculate the energy functions for four subsamples, including apparent non-repeating FRBs (one-offs), repeaters, multi-structural one-offs, and the joint repeaters and multi-structural events, respectively. We then derive the FRB event rates at different redshifts for all four subsamples, all of which were found to share a similar cosmological evolution trend. However, we find that the multi-structural one-offs and repeaters are distinguishable from the KS and MWW tests. Full article

The black aurora is a distinct phenomenon characterized by spatially well-defined regions where the diffuse auroral luminosity decreases notably. Typically, black auroras present as arcs moving at lower velocities, patches with higher moving speeds, and arc segments. However, the mechanism behind black auroras remains unclear. In this paper, we present a novel observation of a poleward-moving black auroral arc associated with impulse-excited field-line resonances in the dawnside sector from the multi-spacecraft THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission, equivalent ionospheric currents, and a conjugated all-sky imager. The field-line resonance velocities exhibit periodic vorticity, which correspond to periodic poleward-moving bands of enhanced FACs. Based on the relatively large reduction in luminosity, we conclude that the poleward-moving black auroral arc was most likely caused by downward FACs associated with field-line resonances. Full article

The theory of equatorward moving east-west elongated auroral arcs associated with field line resonance (FLR) has been proposed for decades. However, confirming this theory requires in-situ observations of FLR within the magnetosphere and simultaneous all-sky imager observations of equatorward moving auroral arcs near satellite footpoints. In this study, we present the first observations of multiple equatorward moving auroral arcs related to impulse-excited FLR, using datasets from the WIND, Geotail satellites, and an all-sky imager at China’s Zhongshan Station (ZHS) in Antarctica. In the presented event, the ultra-low-frequency waves associated with solar wind dynamic pressure pulse was mainly toroidal mode, which is consistent with the theory that the toroidal mode waves usually related with external source. The all-sky imager located in Zhongshan station recorded several equatorward moving auroral arcs, followed by reverse propagating ones. The latitudinal width of the equatorward moving auroral arcs was on the order of 25 km and had an average equatorward propagation of ~0.37 km/s, which is very similar to the value from previous work. To better illustrate the observed evolution of auroral arcs related with the FLRs we proposed a simple model to evaluate the FACs induced by the FLRs in different latitudes. The latitudinal distribution evolution of FACs agrees well with the ground-based optical observations. Full article

In this study, we aim to analyze the electromagnetic interference (EMI) regarding the Five-hundred-meter Aperture Spherical radio Telescope (FAST) caused by base stations in the International Mobile Telecommunications-2000 (IMT-2000) frequency band. By analyzing the frequency bands used by the transmitting and receiving devices and the surrounding environmental parameters and utilizing an approach to predicting radio wave propagation loss that is based on deterministic methods, we conclude by comparing the predicted received power at the FAST with its interference protection threshold. Our analysis demonstrates that, currently, only 55.31% of IMT-2000 base stations in the FAST radio quiet zone (RQZ) meet the protection threshold. Additionally, this article verifies the applicability and accuracy of the radio wave propagation model used in the research based on field strength measurements. Overall, this study provides valuable insights for improving the electromagnetic environment surrounding FAST and reducing the EMI caused by mobile communication base stations. It also provides corresponding analysis methods and useful suggestions for analyzing electromagnetic radiation interference in other radio telescopes. Full article

The study introduces a theory about an Evander-size impact on the surface of Dione. Our study suspects a relatively low-velocity (≤5 km/s) collision between a ca. 50–80 km diameter object and Dione, which might have resulted in the resurfacing of one of the satellite’s intermediate cratered terrains in various ways, such as surface planing by “plowing” by ricocheting ejectiles, ejecta blanket covering, partial melting, and impact-triggered diapir formation associated with cryotectonism and effusive cryo-slurry outflows. Modeling the parameters of an impact of such a size and mapping the potential secondary crater distribution in the target location may function as the first test of plausibility to reveal the location of such a collision, which may be hidden by younger impact marks formed during, e.g., the Antenor, Dido, Romulus, and Remus collision events. The source of the impactor might have been Saturn-specific planetocentric debris, a unique impactor population suspected in the Saturnian system. Other possible candidates are asteroid(s) appearing during the outer Solar System’s heavy bombardment period, or a collision, which might have happened during the “giant impact phase” in the early Saturnian system. Full article

We apply Newtonian fractional-dimension gravity (NFDG), an alternative gravitational model, to some notable cases of galaxies with little or no dark matter. In the case of the ultra-diffuse galaxy AGC 114905, we show that NFDG methods can effectively reproduce the observed rotation curve using a variable fractional dimension $D\left(R\right)$, as was performed for other galaxies in previous studies. For AGC 114905, we obtain a variable dimension in the range $D\approx$ 2.2–3.2, but our fixed D = 3 curve can still fit all the experimental data within their error bars. This confirms other studies indicating that the dynamics of this galaxy can be described almost entirely by the baryonic mass distribution alone. In the case of NGC 1052-DF2, we use an argument based on the NFDG extension of the virial theorem applied to the velocity dispersion of globular clusters showing that, in general, discrepancies between observed and predicted velocity dispersions can be attributed to an overall fractal dimension $D<3$ of the astrophysical structure considered, and not to the presence of dark matter. For NGC 1052-DF2, we estimate $D\approx 2.9$, thus confirming that this galaxy almost follows standard Newtonian behavior. We also consider the case of the Bullet Cluster merger (1E0657-56), assumed to be one of the strongest proofs of dark matter existence. A simplified but effective NFDG model of the collision shows that the observed infall velocity of this merger can be explained by a fractional dimension of the system in the range $D\simeq$ 2.4–2.5, again, without using any dark matter. Full article

Swift has now completed 18 years of mission, during which it discovered thousands of gamma-ray bursts as well as new classes of high-energy transient phenomena. Its first breakthrough result was the localization of short duration GRBs, which enabled for redshift measurements and kilonova searches. Swift, in synergy with the Hubble Space Telescope and a wide array of ground-based telescopes, provided the first tantalizing evidence of a kilonova in the aftermath of a short GRB. In 2017, Swift observations of the gravitational wave event GW170817 captured the early UV photons from the kilonova AT2017gfo, opening a new window into the physics of kilonovae. Since then, Swift has continued to expand the sample of known kilonovae, leading to the surprising discovery of a kilonova in a long duration GRB. This article will discuss recent advances in the study of kilonovae driven by the fundamental contribution of Swift. Full article

The violent stellar explosions known as supernovae have received especially strong attention in both the research community and the general public recently. With the advent of space telescopes, the study of these extraordinary events has switched gears and it has become one of the leading fields in modern astrophysics. In this paper, we review some of the recent developments, focusing mainly on studies related to space-based observations. Full article

Within the scope of a Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological model we study the role of a nonlinear spinor field in the evolution of the universe. In doing so, we exploit the FLRW models given in both Cartesian and spherical coordinates. It is found that if the FLRW model is given in the spherical coordinates the energy-momentum tensor (EMT) of the spinor field possesses nontrivial non-diagonal components, which is not the case for Cartesian coordinates. These non-diagonal components do not depend on either the spinor field nonlinearity or the parameter k that defines the type of curvature of the FLRW model. The presence of such components imposes some restrictions on the spinor field. The problem is studied for open, flat and close geometries and the spinor field is used to simulate different types of sources including dark energies. Some qualitative numerical solutions are given. Full article

At the LHC, the process of a Higgs boson decaying into bottom or charm quarks produced in association with a pair of top quarks, $\mathrm{t}\overline{\mathrm{t}}\mathrm{H}$, allows for an empirical exploration of the heavy-flavor quark Yukawa couplings to the Higgs boson. Accordingly, the cross-sections for the $\mathrm{t}\overline{\mathrm{t}}$ + heavy-flavor production without the appearance of the Higgs boson have been measured at the LHC in various phase spaces using data samples collected in pp collisions at $\sqrt{s}$ = 7, 8 and 13 TeV with the ATLAS and CMS experiments. Flavor ratios of cross-sections of $\mathrm{t}\overline{\mathrm{t}}$ + heavy-flavors to $\mathrm{t}\overline{\mathrm{t}}$ + additionaljets processes are also measured. In this paper, the measured cross-sections and ratios are reviewed and the prospects with more data are presented. Full article

In this paper, we investigate the bosonic Casimir effect in a Lorentz-violating symmetry scenario. The theoretical model adopted consists of a real massive scalar quantum field confined in a region between two large parallel plates, having its dynamics governed by a modified Klein–Gordon equation that presents a Lorentz symmetry-breaking term. In this context, we admit that the quantum field obeys specific boundary conditions on the plates. The Lorentz-violating symmetry is implemented by the presence of an arbitrary constant space-like vector in a CPT-even aether-like approach, considering a direct coupling between this vector with the derivative of the field in higher order. The modification of the Klein–Gordon equation produces important corrections on the Casimir energy and pressure. Thus, we show that these corrections strongly depend on the order of the higher derivative term and the specific direction of the constant vector, as well as the boundary conditions considered. Full article

A systematic analysis of the weak responses for charged-current quasielastic neutrino-nucleus reactions is presented within the scheme of a fully relativistic microscopic model considering momentum-dependent scalar and vector mean field potentials in both the initial and final nucleon states. The responses obtained are compared with the ones corresponding to simpler approaches: energy-independent potentials and the relativistic plane wave limit in the final state, i.e., no potentials applied to the outgoing particle. The analysis is also extended to the scaling phenomenon, which provides additional information regarding nuclear dynamics. Results for the scaling function are shown for various nuclei and different values of the transferred momentum in order to analyze the behavior of the relativistic scalar and vector mean field potentials. Full article

In this work, the perturbed equations of motion of the infinitesimal body are constructed in the framework of the circular restricted three-body problem when the main two bodies are oblate and radiating. Under the perturbations effects of the oblateness and the radiation pressure the positions of collinear Lagrange points are evaluated, the interior and exterior first-order resonant periodic orbits are also studied. In addition, the initial positions of the periodic orbits and the size of loops have been estimated under these effects. Thus, the characteristics of periodic orbits have been studied under the combine effects of two, three and four perturbations for all the possible combinations of the perturbed parameters. The different order of resonant periodic orbits have been also analysed under the effects of Jacobi constant, mass factor, order of resonance and number of loops. Full article

We investigate two physical systems within a spacetime region affected by the nontrivial topology. The set-up for our analysis is a Minkowski metric perturbed by elements reflecting the topological nontriviality. These elements arise when exploring Cartan’s spinorial approach along with the exotic spinors counterpart. This evinced nontrivial topology corrections in the free particle dynamics and charged particles coupled to an external electromagnetic field. As a complement, we show the appearance of a magnetic monopole-like effect. Full article

The study of massive neutrinos and their interactions is a critical aspect of contemporary cosmology. Recent advances in parallel computation and high-performance computing provide new opportunities for accurately constraining Large-Scale Structures (LSS). In this paper, we introduce the TianNu cosmological N-body simulation during the co-evolution of massive neutrino and cold dark matter components via the CUBEP${}^3$M code running on the supercomputer Tianhe-2 and TianNu’s connected works. We start by analyzing $2.537\times {10}^7$ dark halos from the scientific data of TianNu simulation, and compare their angular momentum with the matched halos from neutrino-free TianZero, revealing a dependence of angular momentum modulus on neutrino injection at scales below 50 Mpc and around 10 Mpc. Full article