当前期刊: Universe Go to current issue    加入关注   
显示样式:        排序: IF: - GO 导出
  • Superfluid Neutron Matter with a Twist
    Universe (IF 1.752) Pub Date : 2021-01-26
    Georgios Palkanoglou; Alexandros Gezerlis

    Superfluid neutron matter is a key ingredient in the composition of neutron stars. The physics of the inner crust are largely dependent on those of its S-wave neutron superfluid, which has made its presence known through pulsar glitches and modifications in neutron star cooling. Moreover, with recent gravitational-wave observations of neutron star mergers, the need for an equation of state for the

  • Mixing Uncertainties in Low-Metallicity AGB Stars: The Impact on Stellar Structure and Nucleosynthesis
    Universe (IF 1.752) Pub Date : 2021-01-26
    Umberto Battino; Claudia Lederer-Woods; Borbála Cseh; Pavel Denissenkov; Falk Herwig

    The slow neutron-capture process (s-process) efficiency in low-mass AGB stars (1.5 < M/M⊙ < 3) critically depends on how mixing processes in stellar interiors are handled, which is still affected by considerable uncertainties. In this work, we compute the evolution and nucleosynthesis of low-mass AGB stars at low metallicities using the MESA stellar evolution code. The combined data set includes models

  • Anti-BRST in the Causal Approach
    Universe (IF 1.752) Pub Date : 2021-01-26
    Dan-Radu Grigore

    It is known that the elimination of anomalies in all orders of perturbation theory is an open problem. The constraints given by usual invariance properties and the Wess–Zumino identities are not enough to eliminate the anomalies in the general case of a Yang–Mills theory. So, any new symmetry of the model could restrict further the anomalies and be a solution of the problem. We consider the anti-BRST

  • Comparison of EEJ Longitudinal Variation from Satellite and Ground Measurements over Different Solar Activity Levels
    Universe (IF 1.752) Pub Date : 2021-01-23
    Wan Nur Izzaty Ismail; Nurul Shazana Abdul Hamid; Mardina Abdullah; Akimasa Yoshikawa; Teiji Uozumi; Zahira Mohd Radzi

    The longitudinal variability and local time of equatorial electrojet (EEJ) current using simultaneous data recorded by ground and satellite magnetometers at different levels of solar activity were investigated. In this study, we used data from the CHAMP and Swarm satellites to obtain EEJ current measurements around the globe. The ground data were provided by the MAGDAS, INTERMAGNET, and IIG networks

  • Acknowledgment to Reviewers of Universe in 2020
    Universe (IF 1.752) Pub Date : 2021-01-22
    Universe Editorial Office

    Note: In lieu of an abstract, this is an excerpt from the first page. Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Universe maintains its standards for the high quality of its published papers [...]

  • Curvature Invariants for the Alcubierre and Natário Warp Drives
    Universe (IF 1.752) Pub Date : 2021-01-20
    Brandon Mattingly; Abinash Kar; Matthew Gorban; William Julius; Cooper K. Watson; MD Ali; Andrew Baas; Caleb Elmore; Jeffrey S. Lee; Bahram Shakerin; Eric W. Davis; Gerald B. Cleaver

    A process for using curvature invariants is applied to evaluate the metrics for the Alcubierre and the Natário warp drives at a constant velocity. Curvature invariants are independent of coordinate bases, so plotting these invariants will be free of coordinate mapping distortions. As a consequence, they provide a novel perspective into complex spacetimes, such as warp drives. Warp drives are the theoretical

  • Machine Learning Using Rapidity-Mass Matrices for Event Classification Problems in HEP
    Universe (IF 1.752) Pub Date : 2021-01-19
    Sergei V. Chekanov

    In this work, supervised artificial neural networks (ANN) with rapidity–mass matrix (RMM) inputs are studied using several Monte Carlo event samples for various pp collision processes. The study shows the usability of this approach for general event classification problems. The proposed standardization of the ANN feature space can simplify searches for signatures of new physics at the Large Hadron

  • Correlations between Earthquake Properties and Characteristics of Possible ULF Geomagnetic Precursor over Multiple Earthquakes
    Universe (IF 1.752) Pub Date : 2021-01-19
    Khairul Adib Yusof; Mardina Abdullah; Nurul Shazana Abdul Hamid; Suaidi Ahadi; Akimasa Yoshikawa

    In this study, we improved and adapted existing signal processing methods on vast geomagnetic field data to investigate the correlations between various earthquake properties and characteristics of possible geomagnetic precursors. The data from 10 magnetometer stations were utilized to detect precursory ultra-low frequency emission and estimate the source direction for 34 earthquakes occurring between

  • A Superfluid Perspective on Neutron Star Dynamics
    Universe (IF 1.752) Pub Date : 2021-01-15
    Nils Andersson

    As mature neutron stars are cold (on the relevant temperature scale), one has to carefully consider the state of matter in their interior. The outer kilometre or so is expected to freeze to form an elastic crust of increasingly neutron-rich nuclei, coexisting with a superfluid neutron component, while the star’s fluid core contains a mixed superfluid/superconductor. The dynamics of the star depend

  • The Clustering Dynamics of Primordial Black Boles in N-Body Simulations
    Universe (IF 1.752) Pub Date : 2021-01-15
    Manuel Trashorras; Juan García-Bellido; Savvas Nesseris

    We explore the possibility that Dark Matter (DM) may be explained by a nonuniform background of approximately stellar mass clusters of Primordial Black Holes (PBHs) by simulating the evolution from recombination to the present with over 5000 realisations using a Newtonian \({ N }\)-body code. We compute the cluster rate of evaporation and extract the binary and merged sub-populations along with their

  • Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz
    Universe (IF 1.752) Pub Date : 2021-01-14
    Xiang Liu; Xin Wang; Ning Chang; Jun Liu; Lang Cui; Xiaofeng Yang; Thomas P. Krichbaum

    Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) which are mostly selected from the observing list of RadioAstron AGN monitoring campaigns. The observations were carried out at 4.8 GHz in two sessions of

  • Superfluid Phonons in Neutron Star Core
    Universe (IF 1.752) Pub Date : 2021-01-14
    Marcello Baldo

    In neutron stars the nuclear asymmetric matter is expected to undergo phase transitions to a superfluid state. According to simple estimates, neutron matter in the inner crust and just below should be in the s-wave superfluid phase, corresponding to the neutron-neutron 1S0 channel. At higher density in the core also the proton component should be superfluid, while in the inner core the neutron matter

  • Closed Timelike Curves, Singularities and Causality: A Survey from Gödel to Chronological Protection
    Universe (IF 1.752) Pub Date : 2021-01-12
    Jean-Pierre Luminet

    I give a historical survey of the discussions about the existence of closed timelike curves in general relativistic models of the universe, opening the physical possibility of time travel in the past, as first recognized by K. Gödel in his rotating universe model of 1949. I emphasize that journeying into the past is intimately linked to spacetime models devoid of timelike singularities. Since such

  • Gravitational Dynamics—A Novel Shift in the Hamiltonian Paradigm
    Universe (IF 1.752) Pub Date : 2021-01-12
    Abhay Ashtekar; Madhavan Varadarajan

    It is well known that Einstein’s equations assume a simple polynomial form in the Hamiltonian framework based on a Yang-Mills phase space. We re-examine the gravitational dynamics in this framework and show that time evolution of the gravitational field can be re-expressed as (a gauge covariant generalization of) the Lie derivative along a novel shift vector field in spatial directions. Thus, the canonical

  • Quantum String Cosmology
    Universe (IF 1.752) Pub Date : 2021-01-12
    Maurizio Gasperini

    We present a short review of possible applications of the Wheeler-De Witt equation to cosmological models based on the low-energy string effective action, and characterised by an initial regime of asymptotically flat, low energy, weak coupling evolution. Considering in particular a class of duality-related (but classically disconnected) background solutions, we shall discuss the possibility of quantum

  • Gravitation in Unified Scalar Field Theory
    Universe (IF 1.752) Pub Date : 2021-01-09
    Alexander A. Chernitskii

    The scalar field of space-time film is considered as unified fundamental field. The field model under consideration is the space-time generalization of the model for a two-dimensional thin film. The force and metrical interactions between solitons are considered. These interactions correspond to the electromagnetic and gravitational interactions respectively. The metrical interaction and its correspondence

  • Gravitational Waves in Scalar–Tensor–Vector Gravity Theory
    Universe (IF 1.752) Pub Date : 2021-01-07
    Yunqi Liu; Wei-Liang Qian; Yungui Gong; Bin Wang

    In this paper, we study the properties of gravitational waves in the scalar–tensor–vector gravity theory. The polarizations of the gravitational waves are investigated by analyzing the relative motion of the test particles. It is found that the interaction between the matter and vector field in the theory leads to two additional transverse polarization modes. By making use of the polarization content

  • New Tools for the Optimized Follow-Up of Imminent Impactors
    Universe (IF 1.752) Pub Date : 2021-01-07
    Maddalena Mochi; Giacomo Tommei

    The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Belt. However, some asteroids can run on trajectories that come close to, or even intersect, the orbit of the Earth. These objects are known as Near Earth

  • Statistical Estimates of the Pulsar Glitch Activity
    Universe (IF 1.752) Pub Date : 2021-01-05
    Alessandro Montoli; Marco Antonelli; Brynmor Haskell; Pierre Pizzochero

    A common way to calculate the glitch activity of a pulsar is an ordinary linear regression of the observed cumulative glitch history. This method however is likely to underestimate the errors on the activity, as it implicitly assumes a (long-term) linear dependence between glitch sizes and waiting times, as well as equal variance, i.e., homoscedasticity, in the fit residuals, both assumptions that

  • Neutrino Oscillations in Neutrino-Dominated Accretion Around Rotating Black Holes
    Universe (IF 1.752) Pub Date : 2021-01-04
    Juan David Uribe; Eduar Antonio Becerra-Vergara; Jorge Armando Rueda

    In the binary-driven hypernova model of long gamma-ray bursts, a carbon–oxygen star explodes as a supernova in the presence of a neutron star binary companion in close orbit. Hypercritical (i.e., highly super-Eddington) accretion of the ejecta matter onto the neutron star sets in, making it reach the critical mass with consequent formation of a Kerr black hole. We have recently shown that, during the

  • Isospin Effect on Baryon and Charge Fluctuations from the pNJL Model
    Universe (IF 1.752) Pub Date : 2020-12-31
    He Liu; Jun Xu

    We have studied the possible isospin corrections on the skewness and kurtosis of net-baryon and net-charge fluctuations in the isospin asymmetric matter formed in relativistic heavy-ion collisions at RHIC-BES energies, based on a 3-flavor Polyakov-looped Nambu–Jona–Lasinio model. With typical scalar–isovector and vector–isovector couplings leading to the splitting of u and d quark chiral phase transition

  • Zeta Functions and the Cosmos—A Basic Brief Review
    Universe (IF 1.752) Pub Date : 2020-12-30
    Emilio Elizalde

    This is a very basic and pedagogical review of the concepts of zeta function and of the associated zeta regularization method, starting from the notions of harmonic series and of divergent sums in general. By way of very simple examples, it is shown how these powerful methods are used for the regularization of physical quantities, such as quantum vacuum fluctuations in various contexts. In special

  • The Uniformly Accelerated Frame as a Test Bed for Analysing the Gravitational Redshift
    Universe (IF 1.752) Pub Date : 2020-12-28
    Don Koks

    Ever since Eddington’s analysis of the gravitational redshift a century ago, and the arguments in the relativity community that it produced, fine details of the roles of proper time and coordinate time in the redshift remain somewhat obscure. We shed light on these roles by appealing to the physics of the uniformly accelerated frame, in which coordinate time and proper time are well defined and easy

  • Comparison of Gravitational and Light Frequency Shifts in Rubidium Atomic Clock
    Universe (IF 1.752) Pub Date : 2020-12-24
    Alexey Baranov; Sergey Ermak; Roman Lozov; Vladimir Semenov

    The article presents the results of an experimental study of the external magnetic field orientation and magnitude influence on the rubidium atomic clock, simulating the influence of the geomagnetic field on the onboard rubidium atomic clock of navigation satellites. The tensor component value of the atomic clock frequency light shift on the rubidium cell was obtained, and this value was ~2 Hz. The

  • Particle Acceleration Driven by Null Electromagnetic Fields Near a Kerr Black Hole
    Universe (IF 1.752) Pub Date : 2020-12-22
    Yasufumi Kojima; Yuto Kimura

    Short timescale variability is often associated with a black hole system. The consequence of an electromagnetic outflow suddenly generated near a Kerr black hole is considered assuming that it is described by a solution of a force-free field with a null electric current. We compute charged particle acceleration induced by the burst field. We show that the particle is instantaneously accelerated to

  • Photon Spheres, ISCOs, and OSCOs: Astrophysical Observables for Regular Black Holes with Asymptotically Minkowski Cores
    Universe (IF 1.752) Pub Date : 2020-12-22
    Thomas Berry; Alex Simpson; Matt Visser

    Classical black holes contain a singularity at their core. This has prompted various researchers to propose a multitude of modified spacetimes that mimic the physically observable characteristics of classical black holes as best as possible, but that crucially do not contain singularities at their cores. Due to recent advances in near-horizon astronomy, the ability to observationally distinguish between

  • Dynamical Stability and Geometrical Diagnostic of the Power Law K-Essence Dark Energy Model with Interaction
    Universe (IF 1.752) Pub Date : 2020-12-18
    Bo-Hai Chen; Ya-Bo Wu; Dong-Fang Xu; Wei Dong; Nan Zhang

    We investigate the cosmological evolution of the power law k-essence dark energy (DE) model with interaction in FRWL spacetime with the Lagrangian that contains a kinetic function F(X)=−X+X. Concretely, the cosmological evolution in this model are discussed by the autonomous dynamical system and its critical points, together with the corresponding cosmological quantities, such as Ωϕ, wϕ, cs2, and q

  • Supersymmetric HS Yang-Mills-like Models
    Universe (IF 1.752) Pub Date : 2020-12-18
    Loriano Bonora; Stefano Giaccari

    We introduce the supersymmetric version of YM-like theories with infinitely many spin fields in four dimensions. The construction is carried out via the superfield method. The surprising feature of these models is that they describe, in particular, gauge and gravity in a supersymmetric form, with no need for supergravity.

  • An Improved Framework for Quantum Gravity
    Universe (IF 1.752) Pub Date : 2020-12-16
    José G. Pereira; Diego F. López

    General relativity has two fundamental problems that render it unsuitable for tackling the gravitational field’s quantization. The first problem is the lack of a genuine gravitational variable representing gravitation only, inertial forces apart. The second problem is its incompatibility with quantum mechanics, a problem inherited from the more fundamental conflict of special relativity with quantum

  • Editorial for the Special Issue “Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves”
    Universe (IF 1.752) Pub Date : 2020-12-15
    Banibrata Mukhopadhyay

    Note: In lieu of an abstract, this is an excerpt from the first page. The present Editorial introduces the Special Issue dedicated by the journal Universe to the “Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves” [...]

  • Double Beta Decay to Excited States of Daughter Nuclei
    Universe (IF 1.752) Pub Date : 2020-12-13
    Pierluigi Belli; Rita Bernabei; Fabio Cappella; Vincenzo Caracciolo; Riccardo Cerulli; Antonella Incicchitti; Vittorio Merlo

    In this paper we review results obtained in the searches of double beta decays to excited states of the daughter nuclei and illustrate the related experimental techniques. In particular, we describe in some detail the only two cases in which the transition has been observed; that is the 2β−(0+→01+) decay of 100Mo and 150Nd nuclides. Moreover, the most significant results in terms of lower limits on

  • Post-Editorial of the Special Issue “Estate Quantistica Conference—Recent Developments in Gravity, Cosmology, and Mathematical Physics”
    Universe (IF 1.752) Pub Date : 2020-12-13
    Hermano Velten; Giuseppe Dito

    Note: In lieu of an abstract, this is an excerpt from the first page. This editorial summarizes the contributions presented during the Estate Quantistica 2018 and published in a special issue of Universe [...]

  • Uniqueness Criteria for the Fock Quantization of Dirac Fields and Applications in Hybrid Loop Quantum Cosmology
    Universe (IF 1.752) Pub Date : 2020-12-13
    Jerónimo Cortez; Beatriz Elizaga Navascués; Guillermo A. Mena Marugán; Santiago Prado; José M. Velhinho

    In generic curved spacetimes, the unavailability of a natural choice of vacuum state introduces a serious ambiguity in the Fock quantization of fields. In this review, we study the case of fermions described by a Dirac field in non-stationary spacetimes, and present recent results obtained by us and our collaborators about well-motivated criteria capable to ensure the uniqueness in the selection of

  • The Montevideo Interpretation: How the Inclusion of a Quantum Gravitational Notion of Time Solves the Measurement Problem
    Universe (IF 1.752) Pub Date : 2020-12-11
    Rodolfo Gambini; Jorge Pullin

    We review the Montevideo Interpretation of quantum mechanics, which is based on the use of real clocks to describe physics, using the framework that was recently introduced by Höhn, Smith, and Lock to treat the problem of time in generally covariant systems. These new methods, which solve several problems in the introduction of a notion of time in such systems, do not change the main results of the

  • Relativistic Combination of Non-Collinear 3-Velocities Using Quaternions
    Universe (IF 1.752) Pub Date : 2020-12-11
    Thomas Berry; Matt Visser

    Quaternions have an (over a century-old) extensive and quite complicated interaction with special relativity. Since quaternions are intrinsically 4-dimensional, and do such a good job of handling 3-dimensional rotations, the hope has always been that the use of quaternions would simplify some of the algebra of the Lorentz transformations. Herein we report a new and relatively nice result for the relativistic

  • Fundamental Symmetries and Spacetime Geometries in Gauge Theories of Gravity—Prospects for Unified Field Theories
    Universe (IF 1.752) Pub Date : 2020-12-11
    Francisco Cabral; Francisco S. N. Lobo; Diego Rubiera-Garcia

    Gravity can be formulated as a gauge theory by combining symmetry principles and geometrical methods in a consistent mathematical framework. The gauge approach to gravity leads directly to non-Euclidean, post-Riemannian spacetime geometries, providing the adequate formalism for metric-affine theories of gravity with curvature, torsion and non-metricity. In this paper, we analyze the structure of gauge

  • Editorial for the Special Issue “Quantum Fields—From Fundamental Concepts to Phenomenological Questions”
    Universe (IF 1.752) Pub Date : 2020-12-10
    Astrid Eichhorn; Roberto Percacci; Frank Saueressig

    Note: In lieu of an abstract, this is an excerpt from the first page. Quantum field theory and Einstein’s theory of general relativity are extremely successful in predicting the outcome of particle physics and gravitational experiments [...]

  • Dark Matter as Gravitational Solitons in the Weak Field Limit
    Universe (IF 1.752) Pub Date : 2020-12-09
    Torsten Asselmeyer-Maluga; Jerzy Król

    In this paper, we will describe the idea that dark matter partly consists of gravitational solitons (gravisolitons). The corresponding solution is valid for weak gravitational fields (weak field limit) with respect to a background metric. The stability of this soliton is connected with the existence of a special foliation and amazingly with the smoothness properties of spacetime. Gravisolitons have

  • Beyond General Relativity: Models for Quantum Gravity, Loop Quantum Cosmology and Black Holes
    Universe (IF 1.752) Pub Date : 2020-12-07
    Nick E. Mavromatos

    Note: In lieu of an abstract, this is an excerpt from the first page. In the past two decades, we have witnessed extraordinary progress in precision measurements in cosmology [...]

  • Present Status of Nuclear Shell-Model Calculations of 0νββ Decay Matrix Elements
    Universe (IF 1.752) Pub Date : 2020-12-07
    Luigi Coraggio; Nunzio Itaco; Giovanni De Gregorio; Angela Gargano; Riccardo Mancino; Saori Pastore

    Neutrinoless double beta (0νββ) decay searches are currently among the major foci of experimental physics. The observation of such a decay will have important implications in our understanding of the intrinsic nature of neutrinos and shed light on the limitations of the Standard Model. The rate of this process depends on both the unknown neutrino effective mass and the nuclear matrix element (M0ν)

  • The Solution of the Cosmological Constant Problem: The Cosmological Constant Exponential Decrease in the Super-Early Universe
    Universe (IF 1.752) Pub Date : 2020-12-04
    Ol’ga Babourova; Boris Frolov

    The stage of a super-early (primordial) scale-invariant Universe is considered on the basis of the Poincaré–Weyl gauge theory of gravity in a Cartan–Weyl space-time. An approximate solution has been found that demonstrates an inflationary behavior of the scale factor and, at the same time, a sharp exponential decrease in the effective cosmological constant from a huge value at the beginning of the

  • Constraint on Hybrid Stars with Gravitational Wave Events
    Universe (IF 1.752) Pub Date : 2020-12-04
    Kilar Zhang; Feng-Li Lin

    Motivated by the recent discoveries of compact objects from LIGO/Virgo observations, we study the possibility of identifying some of these objects as compact stars made of dark matter called dark stars, or the mix of dark and nuclear matters called hybrid stars. In particular, in GW190814, a new compact object with 2.6 M⊙ is reported. This could be the lightest black hole, the heaviest neutron star

  • Toward Nonlocal Electrodynamics of Accelerated Systems
    Universe (IF 1.752) Pub Date : 2020-12-03
    Bahram Mashhoon

    We revisit acceleration-induced nonlocal electrodynamics and the phenomenon of photon spin-rotation coupling. The kernel of the theory for the electromagnetic field tensor involves parity violation under the assumption of linearity of the field kernel in the acceleration tensor. However, we show that parity conservation can be maintained by extending the field kernel to include quadratic terms in the

  • New Scenarios of High-Energy Particle Collisions Near Wormholes
    Universe (IF 1.752) Pub Date : 2020-11-30
    Oleg B. Zaslavskii

    We suggest two new scenarios of high-energy particle collisions in the background of a wormhole. In scenario 1, the novelty consists of the fact that the effect does not require two particles coming from different mouths. Instead, all such scenarios of high energy collisions develop, when an experimenter sends particles towards a wormhole from the same side of the throat. For static wormholes, this

  • Post-Editorial of the Special Issue “Wormholes in Space-Time: Theory and Facts”
    Universe (IF 1.752) Pub Date : 2020-11-30
    Francisco S. N. Lobo; Gonzalo J. Olmo; Diego Rubiera-Garcia

    Note: In lieu of an abstract, this is an excerpt from the first page. Wormholes made their first appearance in gravitational physics as soon as in 1916 but, as with their black hole cousins, it took a long time and effort for their true nature to be properly understood [...]

  • Rotation Effects in Relativity
    Universe (IF 1.752) Pub Date : 2020-11-27
    Matteo Luca Ruggiero

    Note: In lieu of an abstract, this is an excerpt from the first page. Rotation has always been a central thread in physics and has influenced its development [...]

  • Jeans Instability of Dissipative Self-Gravitating Bose–Einstein Condensates with Repulsive or Attractive Self-Interaction: Application to Dark Matter
    Universe (IF 1.752) Pub Date : 2020-11-27
    Pierre-Henri Chavanis

    We study the Jeans instability of an infinite homogeneous dissipative self-gravitating Bose–Einstein condensate described by generalized Gross–Pitaevskii–Poisson equations [Chavanis, P.H. Eur. Phys. J. Plus 2017, 132, 248]. This problem has applications in relation to the formation of dark matter halos in cosmology. We consider the case of a static and an expanding universe. We take into account an

  • Neutrino-Mass Sensitivity and Nuclear Matrix Element for Neutrinoless Double Beta Decay
    Universe (IF 1.752) Pub Date : 2020-11-27
    Hiroyasu Ejiri

    Neutrinoless double beta decay (DBD) is a useful probe to study neutrino properties such as the Majorana nature, the absolute neutrino mass, the CP phase and the others, which are beyond the standard model. The nuclear matrix element (NME) for DBD is crucial to extract the neutrino properties from the experimental transition rate. The neutrino-mass sensitivity, i.e., the minimum neutrino-mass to be

  • Can a Chameleon Field Be Identified with Quintessence?
    Universe (IF 1.752) Pub Date : 2020-11-26
    A. N. Ivanov; M. Wellenzohn

    In the Einstein–Cartan gravitational theory with the chameleon field, while changing its mass independently of the density of its environment, we analyze the Friedmann–Einstein equations for the Universe’s evolution with the expansion parameter a being dependent on time only. We analyze the problem of an identification of the chameleon field with quintessence, i.e., a canonical scalar field responsible

  • Studying Asymptotic Giant Branch Stars in the JWST Era
    Universe (IF 1.752) Pub Date : 2020-11-26
    Paolo Ventura; Ester Marini; Silvia Tosi; Flavia Dell’Agli

    We explore the potential offered by the incoming launch of the James Webb Space Telescope, to study the stars evolving through the asymptotic giant branch (AGB) phase. To this aim we compare data of AGB stars in the Large Magellanic Cloud, taken with the IRS spectrograph, with the results from modelling of AGB evolution and dust formation in the wind. We find that the best diagrams to study M- and

  • Neutron Stars and Dark Matter
    Universe (IF 1.752) Pub Date : 2020-11-26
    Antonino Del Popolo; Morgan Le Delliou; Maksym Deliyergiyev

    Neutron stars change their structure with accumulation of dark matter. We study how their mass is influenced from the environment. Close to the sun, the dark matter accretion from the neutron star does not have any effect on it. Moving towards the galactic center, the density increase in dark matter results in increased accretion. At distances of some fraction of a parsec, the neutron star acquire

  • Neutron Star Properties: Quantifying the Effect of the Crust–Core Matching Procedure
    Universe (IF 1.752) Pub Date : 2020-11-23
    Márcio Ferreira; Constança Providência

    The impact of the equation of state (EoS) crust-core matching procedure on neutron star (NS) properties is analyzed within a meta-modeling approach. Using a Taylor expansion to parametrize the core equation of state (EoS) and the SLy4 crust EoS, we create two distinct EoS datasets employing two matching procedures. Each EoS describes cold NS matter in a β equilibrium that is thermodynamically stable

  • X-ray Properties of 3C 111: Separation of Primary Nuclear Emission and Jet Continuum
    Universe (IF 1.752) Pub Date : 2020-11-21
    Elena Fedorova; B.I. Hnatyk; V.I. Zhdanov; A. Del Popolo

    3C111 is BLRG with signatures of both FSRQ and Sy1 in X-ray spectrum. The significant X-ray observational dataset was collected for it by INTEGRAL, XMM-Newton, SWIFT, Suzaku and others. The overall X-ray spectrum of 3C 111 shows signs of a peculiarity with the large value of the high-energy cut-off typical rather for RQ AGN, probably due to the jet contamination. Separating the jet counterpart in the

  • On the Collision of Relativistic Shock Waves and the Large Scale Structure of the Universe
    Universe (IF 1.752) Pub Date : 2020-11-20
    Alexander Golubiatnikov; Daniil Lyuboshits

    The solution to the problem of symmetric collision of two relativistic shock waves is given and limiting cases are investigated: Newtonian mechanics and ultrarelativistic mechanics. The results are correlated with the presence of known superclusters and "walls" in the Universe.

  • The Line-of-Sight Analysis of Spatial Distribution of Galaxies in the COSMOS2015 Catalogue
    Universe (IF 1.752) Pub Date : 2020-11-20
    Maxim Nikonov; Mikhail Chekal; Stanislav Shirokov; Andrey Baryshev; Vladimir Gorokhov

    New observations of high-redshift objects are crucial for the improvement of the standard ΛCDM cosmological model and our understanding of the Universe. One of the main directions of modern observational cosmology is the analysis of the large-scale structure of Universe, in particular, in deep fields. We study the large-scale structure of the Universe along the line of sight using the latest version

  • String-Inspired Running Vacuum—The “Vacuumon”—And the Swampland Criteria
    Universe (IF 1.752) Pub Date : 2020-11-20
    Nick E. Mavromatos; Joan Solà Peracaula; Spyros Basilakos

    We elaborate further on the compatibility of the “vacuumon potential” that characterises the inflationary phase of the running vacuum model (RVM) with the swampland criteria. The work is motivated by the fact that, as demonstrated recently by the authors, the RVM framework can be derived as an effective gravitational field theory stemming from underlying microscopic (critical) string theory models

  • Density Operator Approach to Turbulent Flows in Plasma and Atmospheric Fluids
    Universe (IF 1.752) Pub Date : 2020-11-20
    Konstantin G. Zloshchastiev

    We formulate a statistical wave-mechanical approach to describe dissipation and instabilities in two-dimensional turbulent flows of magnetized plasmas and atmospheric fluids, such as drift and Rossby waves. This is made possible by the existence of Hilbert space, associated with the electric potential of plasma or stream function of atmospheric fluid. We therefore regard such turbulent flows as macroscopic

  • Nuclear Response to Second-Order Isospin Probes in Connection to Double Beta Decay
    Universe (IF 1.752) Pub Date : 2020-11-20
    Francesco Cappuzzello; Manuela Cavallaro

    One of the key ingredients needed to extract quantitative information on neutrino absolute mass scale from the possible measurement of the neutrinoless double-beta (0νββ) decay half-lives is the nuclear matrix element (NME) characterizing such transitions. NMEs are not physical observables and can only be deduced by theoretical calculations. However, since the atomic nuclei involved in the decay are

  • The Reconstruction of Non-Minimal Derivative Coupling Inflationary Potentials
    Universe (IF 1.752) Pub Date : 2020-11-19
    Qin Fei; Zhu Yi; Yingjie Yang

    We derive the reconstruction formulae for the inflation model with the non-minimal derivative coupling term. If reconstructing the potential from the tensor-to-scalar ratio r, we could obtain the potential without using the high friction limit. As an example, we reconstruct the potential from the parameterization r=8α/(N+β)γ, which is a general form of the α-attractor. The reconstructed potential has

  • Einstein’s Geometrical Versus Feynman’s Quantum-Field Approaches to Gravity Physics: Testing by Modern Multimessenger Astronomy
    Universe (IF 1.752) Pub Date : 2020-11-18
    Yurij Baryshev

    Modern multimessenger astronomy delivers unique opportunity for performing crucial observations that allow for testing the physics of the gravitational interaction. These tests include detection of gravitational waves by advanced LIGO-Virgo antennas, Event Horizon Telescope observations of central relativistic compact objects (RCO) in active galactic nuclei (AGN), X-ray spectroscopic observations of

Contents have been reproduced by permission of the publishers.
Springer 纳米技术权威期刊征稿
ACS ES&T Engineering
ACS ES&T Water