Congratulations to Prof. Roger Penrose, Advisory Board member of Universe, for receiving the Nobel Prize in Physics 2020.
Journal Description
Universe
Universe
is a peer-reviewed open access journal focused on principles and new discoveries in the universe. Universe is published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Astrophysics Data System, INSPIRE, CAPlus / SciFinder, Inspec, and other databases.
- Journal Rank: JCR - Q2 (Astronomy & Astrophysics) / CiteScore - Q2 (General Physics and Astronomy)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 20.6 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Astronomy.
Impact Factor:
2.9 (2022);
5-Year Impact Factor:
2.4 (2022)
Latest Articles
Conformally Invariant Gravity and Gravitating Mirages
Universe 2024, 10(3), 147; https://doi.org/10.3390/universe10030147 - 17 Mar 2024
Abstract
The action of an ideal fluid in Euler variables with a variable number of particles is used for the phenomenological description of the processes of particle creation in strong external fields. It has been demonstrated that the conformal invariance of the creation law
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The action of an ideal fluid in Euler variables with a variable number of particles is used for the phenomenological description of the processes of particle creation in strong external fields. It has been demonstrated that the conformal invariance of the creation law imposes quite strict restrictions on the possible types of sources. It is shown that combinations with the particle number density in the creation law can be interpreted as dark matter within the framework of this model.
Full article
(This article belongs to the Special Issue The Friedmann Cosmology: A Century Later)
Open AccessReview
The ASTRI Mini-Array: A New Pathfinder for Imaging Cherenkov Telescope Arrays
by
Salvatore Scuderi
Universe 2024, 10(3), 146; https://doi.org/10.3390/universe10030146 - 16 Mar 2024
Abstract
The ASTRI Mini-Array is an Istituto Nazionale di Astrofisica (INAF) project to build and operate an array of nine Imaging Atmospheric Cherenkov Telescopes (IACTs) at the Teide Astronomical Observatory of the Instituto de Astrofisica de Canarias in Tenerife (Spain) based on a host
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The ASTRI Mini-Array is an Istituto Nazionale di Astrofisica (INAF) project to build and operate an array of nine Imaging Atmospheric Cherenkov Telescopes (IACTs) at the Teide Astronomical Observatory of the Instituto de Astrofisica de Canarias in Tenerife (Spain) based on a host agreement with INAF and, as such, it will be the largest IACT array until the Cherenkov Telescope Array Observatory starts operations. Implementing the ASTRI Mini-Array poses several challenges from technical, logistic, and management points of view. Starting from the description of the innovative technologies adopted to build the telescopes, we will discuss the solutions adopted to overcome these challenges, making the ASTRI Mini-Array a great instrument to perform deep observations of the galactic and extra-galactic sky at very high energies.
Full article
(This article belongs to the Special Issue Recent Advances in Gamma Ray Astrophysics and Future Perspectives)
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Open AccessArticle
Multiple SSO Space Debris Flyby Trajectory Design Based on Cislunar Orbit
by
Siyang Zhang and Shuquan Wang
Universe 2024, 10(3), 145; https://doi.org/10.3390/universe10030145 - 16 Mar 2024
Abstract
This paper investigates the trajectory design problem in the scenario of a multiple Sun-synchronous Orbit (SSO) space debris flyby mission from a DRO space station. At first, the characteristics of non-planar transfer from DRO to SSO in the Earth–Moon system are analyzed. The
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This paper investigates the trajectory design problem in the scenario of a multiple Sun-synchronous Orbit (SSO) space debris flyby mission from a DRO space station. At first, the characteristics of non-planar transfer from DRO to SSO in the Earth–Moon system are analyzed. The methods of large-scale ergodicity and pruning are utilized to investigate single-impulse and two-impulse DRO–Earth transfers. Using a powered lunar flyby, the two-impulse DRO–Earth transfer is able to fly by SSO debris while satisfying the requirements of the mission. After the local optimization, the optimal result of two-impulse DRO–Earth transfer and flyby is obtained. A multi-objective evolutionary algorithm is used to design the Pareto-optimal trajectories of multiple flybys. The semi-analytical optimization method is developed to provide the estimations of the transfer parameters in order to reduce the computations caused by the evolutionary algorithm. Simulations show that transferring from the 3:2 resonant DRO to a near-coplanar flyby of a SSO target debris using a powered lunar gravity assist needs a 0.47 km/s velocity increment. The mission’s total velocity increment is 1.39 km/s, and the total transfer time is 2.23 years.
Full article
(This article belongs to the Topic Techniques and Science Exploitations for Earth Observation and Planetary Exploration)
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Open AccessEditorial
Origins and Natures of Inflation, Dark Matter and Dark Energy
by
Kazuharu Bamba
Universe 2024, 10(3), 144; https://doi.org/10.3390/universe10030144 - 15 Mar 2024
Abstract
Various precise cosmological observations, e [...]
Full article
(This article belongs to the Special Issue Origins and Natures of Inflation, Dark Matter and Dark Energy)
Open AccessArticle
The Relevance of Dynamical Friction for the MW/LMC/SMC Triple System
by
Wolfgang Oehm and Pavel Kroupa
Universe 2024, 10(3), 143; https://doi.org/10.3390/universe10030143 - 14 Mar 2024
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Simulations of structure formation in the standard cold dark matter cosmological model quantify the dark matter halos of galaxies. Taking into account dynamical friction between dark matter halos, we investigate the past orbital dynamical evolution of the Magellanic Clouds in the presence of
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Simulations of structure formation in the standard cold dark matter cosmological model quantify the dark matter halos of galaxies. Taking into account dynamical friction between dark matter halos, we investigate the past orbital dynamical evolution of the Magellanic Clouds in the presence of the Galaxy. Our calculations are based on a three-body model of rigid Navarro–Frenk–White profiles for dark matter halos but were verified in a previous publication by comparison to high-resolution N-body simulations of live self-consistent systems. Under the requirement that the LMC and SMC had an encounter within 20 kpc between 1 and 4 Gyr ago in order to allow the development of the Magellanic Stream, using the latest astrometric data, the dynamical evolution of the MW/LMC/SMC system is calculated backwards in time. With the employment of the genetic algorithm and a Markov-Chain Monte-Carlo method, the present state of this system is unlikely, with a probability of ( complement), because the solutions found do not fit into the error bars for the observed plane-of-sky velocity components of the Magellanic Clouds. This implies that orbital solutions that assume dark matter halos, according to cosmological structure formation theory, to exist around the Magellanic Clouds and the Milky Way are not possible with a confidence of more than 6 sigma.
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Open AccessArticle
On the Apparent Discretization of Spacetime and Its Connection with the Cosmological Constant
by
Jaume Giné and Giuseppe Gaetano Luciano
Universe 2024, 10(3), 142; https://doi.org/10.3390/universe10030142 - 14 Mar 2024
Abstract
The emergence of a minimal observable length of order of the Planck scale is a prediction of many quantum theories of gravity. However, the question arises as to whether this is a real fundamental length affecting nature in all of its facets, including
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The emergence of a minimal observable length of order of the Planck scale is a prediction of many quantum theories of gravity. However, the question arises as to whether this is a real fundamental length affecting nature in all of its facets, including spacetime. In this work, we show that the quantum measurement process implies the existence of a minimal measurable length and consequently the apparent discretization of spacetime. The obtained result is used to infer the value of zero-point energy in the universe, which is found to be in good agreement with the observed cosmological constant. This potentially offers some hints towards the resolution of the cosmological constant problem.
Full article
(This article belongs to the Section Foundations of Quantum Mechanics and Quantum Gravity)
Open AccessArticle
Constraining the Initial Mass Function in the Epoch of Reionization from Astrophysical and Cosmological Data
by
Andrea Lapi, Giovanni Gandolfi, Lumen Boco, Francesco Gabrielli, Marcella Massardi, Balakrishna S. Haridasu, Carlo Baccigalupi, Alessandro Bressan and Luigi Danese
Universe 2024, 10(3), 141; https://doi.org/10.3390/universe10030141 - 13 Mar 2024
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We aim to constrain the stellar initial mass function (IMF) during the epoch of reionization. To this purpose, we build up a semi-empirical model for the reionization history of the Universe based on various ingredients: the latest determination of the UV galaxy luminosity
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We aim to constrain the stellar initial mass function (IMF) during the epoch of reionization. To this purpose, we build up a semi-empirical model for the reionization history of the Universe based on various ingredients: the latest determination of the UV galaxy luminosity function from JWST out to redshift ; data-inferred and simulation-driven assumptions on the redshift-dependent escape fraction of ionizing photons from primordial galaxies; a simple yet flexible parameterization of the IMF ∼ in terms of a high-mass end slope and a characteristic mass , below which a flattening or a bending sets in (allowing description of a variety of IMF shapes from the classic Salpeter to top-heavy ones); the PARSEC stellar evolution code to compute the UV and ionizing emission from different stars’ masses as a function of age and metallicity; and a few physical constraints related to stellar and galaxy formation in faint galaxies at the reionization redshifts. We then compare our model outcomes with the reionization observables from different astrophysical and cosmological probes and perform Bayesian inference on the IMF parameters via a standard MCMC technique. We find that the IMF slope is within the range from to , consistent with direct determination from star counts in the Milky Way, while appreciably flatter slopes are excluded at great significance. However, the bestfit value of the IMF characteristic mass ∼a few implies a suppression in the formation of small stellar masses at variance with the IMF in the local Universe. This may be induced by the thermal background of ∼20–30 K provided by CMB photons at the reionization redshifts. We check that our results are robust against different parameterizations for the redshift evolution of the escape fraction. Finally, we investigate the implications of our reconstructed IMF for the recent JWST detections of massive galaxies at and beyond the reionization epoch, showing that any putative tension with the standard cosmological framework is substantially alleviated.
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Open AccessArticle
A Critical Discussion on the H0 Tension
by
Salvatore Capozziello, Giuseppe Sarracino and Giulia De Somma
Universe 2024, 10(3), 140; https://doi.org/10.3390/universe10030140 - 13 Mar 2024
Abstract
A critical discussion on the Hubble constant tension is presented by considering both early and late-type observations. From recent precise measurements, discrepancies emerge when comparing results for some cosmological quantities obtained at different redshifts. We highlight the most relevant measurements of
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A critical discussion on the Hubble constant tension is presented by considering both early and late-type observations. From recent precise measurements, discrepancies emerge when comparing results for some cosmological quantities obtained at different redshifts. We highlight the most relevant measurements of and propose potential ideas to solve its tension. These solutions concern the exploration of new physics beyond the CDM model or the evaluation of by other methods. In particular, we focus on the role of the look-back time.
Full article
(This article belongs to the Special Issue The Friedmann Cosmology: A Century Later)
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Open AccessCommunication
Nuclear Modification Factor of Inclusive Charged Particles in Au+Au Collisions at
by
Alisher Aitbayev
Universe 2024, 10(3), 139; https://doi.org/10.3390/universe10030139 - 13 Mar 2024
Abstract
The Beam Energy Scan (BES) program at RHIC aims to explore the QCD phase diagram, including the search for the evidence of the 1st order phase transition from hadronic matter to Quark-Gluon Plasma (QGP) and the location of the QCD critical point. One
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The Beam Energy Scan (BES) program at RHIC aims to explore the QCD phase diagram, including the search for the evidence of the 1st order phase transition from hadronic matter to Quark-Gluon Plasma (QGP) and the location of the QCD critical point. One of the features previously observed in the study of QGP is the effect of suppression of particle production with high transverse momenta (>2 GeV/c) at energies = GeV, which was deduced from the charged-particle nuclear modification factor ( ) measured using the data from Beam Energy Scan Program Phase I (BES-I) of STAR experiment. In 2018, STAR has collected over 500 million events from + collisions at = 27 GeV as a part of the STAR BES-II program, which is about a factor of 10 higher than BES-I 27 GeV data size. In this report, we present new measurements of charged particle production and the nuclear modification factor , from this new 27 GeV data set and compare them with the BES-I results. The new measurements extend the previous BES-I results to higher transverse momentum range, which allows better exploration of the jet quenching effects at low RHIC energies, and may help to understand the effects of the formation and properties of QGP at these energies.
Full article
(This article belongs to the Special Issue Multiparticle Dynamics)
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Open AccessArticle
Classification of Planetary Motion around Super-Jupiters and Brown Dwarfs
by
Euaggelos E. Zotos, Eman M. Moneer and Tobias C. Hinse
Universe 2024, 10(3), 138; https://doi.org/10.3390/universe10030138 - 13 Mar 2024
Abstract
We investigate the orbital dynamics of an exosystem consisting of a solar-mass host star, a transiting body, and an Earth-size exoplanet within the framework of the generalized three-body problem. Depending on its mass, the transiting body can either be a super-Jupiter or a
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We investigate the orbital dynamics of an exosystem consisting of a solar-mass host star, a transiting body, and an Earth-size exoplanet within the framework of the generalized three-body problem. Depending on its mass, the transiting body can either be a super-Jupiter or a brown dwarf. To determine the final states of the Earth-size exoplanet, we conduct a systematic and detailed classification of the available phase space trajectories. Our classification scheme distinguishes between the bounded, escape, and collisional motions of the Earth-size exoplanet. Additionally, for cases of ordered (regular) motion, we further categorize the associated initial conditions based on the geometry of their respective trajectories. These bounded regular trajectories hold significant importance as they provide insights into the regions of phase space where the motion of the Earth-size exoplanet can be dynamically stable. Of particular interest is the identification of initial conditions that result in a bounded exomoon-like orbit of the Earth-size exoplanet around the transiting body.
Full article
(This article belongs to the Special Issue Formation and Evolution of Exoplanets)
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Open AccessArticle
Regular Friedmann Universes and Matter Transformations
by
Alexander Kamenshchik and Polina Petriakova
Universe 2024, 10(3), 137; https://doi.org/10.3390/universe10030137 - 13 Mar 2024
Abstract
We apply a very simple procedure to construct non-singular cosmological models for flat Friedmann universes filled with minimally coupled scalar fields or by tachyon Born–Infeld-type fields. Remarkably, for the minimally coupled scalar field and the tachyon field, the regularity of the cosmological evolution,
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We apply a very simple procedure to construct non-singular cosmological models for flat Friedmann universes filled with minimally coupled scalar fields or by tachyon Born–Infeld-type fields. Remarkably, for the minimally coupled scalar field and the tachyon field, the regularity of the cosmological evolution, or in other words, the existence of bounce, implies the necessity of the transition between scalar fields with standard kinetic terms to those with phantom ones. In both cases, the potentials in the vicinity of the point of the transition have a non-analyticity of the cusp form that is characterized by the same exponent and is equal to . If, in the tachyon model’s evolution, the pressure changes its sign, then another transformation of the Born–Infeld-type field occurs: the tachyon transforms into a pseudotachyon, and vice versa. We also undertake an analysis of the stability of the cosmological evolution in our models; we rely on the study of the speed of sound squared.
Full article
(This article belongs to the Special Issue The Friedmann Cosmology: A Century Later)
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Open AccessArticle
The Quantum Hall Effect under the Influence of Gravity and Inertia: A Unified Approach
by
Alexandre Landry, Fayçal Hammad and Reza Saadati
Universe 2024, 10(3), 136; https://doi.org/10.3390/universe10030136 - 13 Mar 2024
Abstract
The quantum Hall effect under the influence of gravity and inertia is studied in a unified way. We make use of an algebraic approach, as opposed to an analytic approach. We examine how both the integer and the fractional quantum Hall effects behave
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The quantum Hall effect under the influence of gravity and inertia is studied in a unified way. We make use of an algebraic approach, as opposed to an analytic approach. We examine how both the integer and the fractional quantum Hall effects behave under a combined influence of gravity and inertia using a unified Hamiltonian. For that purpose, we first re-derive, using the purely algebraic method, the energy spectrum of charged particles moving in a plane perpendicular to a constant and uniform magnetic field either (i) under the influence of a nonlinear gravitational potential or (ii) under the influence of a constant rotation. The general Hamiltonian for describing the combined effect of gravity, rotation and inertia on the electrons of a Hall sample is then built and the eigenstates are obtained. The electrons mutual Coulomb interaction that gives rise to the familiar fractional quantum Hall effect is also discussed within such a combination.
Full article
(This article belongs to the Section Gravitation)
Open AccessReview
Isovector Axial Charge and Form Factors of Nucleons from Lattice QCD
by
Rajan Gupta
Universe 2024, 10(3), 135; https://doi.org/10.3390/universe10030135 - 12 Mar 2024
Abstract
A survey of the calculations of the isovector axial vector form factor of the nucleon using lattice QCD is presented. Attention is paid to statistical and systematic uncertainties, in particular those due to excited state contributions. Based on a comparison of results from
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A survey of the calculations of the isovector axial vector form factor of the nucleon using lattice QCD is presented. Attention is paid to statistical and systematic uncertainties, in particular those due to excited state contributions. Based on a comparison of results from various collaborations, a case is made that lattice results are consistent within 10%. A similar level of uncertainty is in the axial charge , the mean squared axial charge radius , the induced pseudoscalar charge , and the pion–nucleon coupling . Even with the current methodology, a significant reduction in errors is expected over the next few years with higher statistics data on more ensembles closer to the physical point. Lattice QCD results for the form factor are compatible with those obtained from the recent MINER A experiment but lie 2–3 higher than the phenomenological extraction from the old –deuterium bubble chamber scattering data for GeV2. Current data show that the dipole ansatz does not have enough parameters to fit the form factor over the range GeV2, whereas even a truncation of the z expansion or a low order Padé are sufficient. Looking ahead, lattice QCD calculations will provide increasingly precise results over the range GeV2, and MINER A-like experiments will extend the range to GeV2 or higher. Nevertheless, improvements in lattice methods to (i) further control excited state contributions and (ii) extend the range of are needed.
Full article
(This article belongs to the Special Issue Neutron Lifetime)
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Open AccessArticle
Weak Coupling Regime in Dilatonic
by
Francisco A. Brito, Carlos H. A. B. Borges, José A. V. Campos and Francisco G. Costa
Universe 2024, 10(3), 134; https://doi.org/10.3390/universe10030134 - 11 Mar 2024
Abstract
We consider modified theories of gravity in the context of string-theory-inspired dilaton gravity. We deal with a specific model that under certain conditions describes the late time Universe in accord with observational data in modern cosmology and
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We consider modified theories of gravity in the context of string-theory-inspired dilaton gravity. We deal with a specific model that under certain conditions describes the late time Universe in accord with observational data in modern cosmology and addresses the tension. This is done by exploring the space of parameters made out of those coming from the modified gravity and dilatonic charge sectors. We employ numerical methods to obtain several important observable quantities.
Full article
(This article belongs to the Special Issue Universe: Feature Papers 2023—Cosmology)
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Open AccessArticle
Analysis of the Geodesic Motions of Massive Particles in Kerr–Sen–AdS4 Spacetime
by
Ziqiang Cai, Ming Liu, Wen-Qian Wang, Tong-Yu He, Zhan-Wen Han and Rong-Jia Yang
Universe 2024, 10(3), 133; https://doi.org/10.3390/universe10030133 - 08 Mar 2024
Abstract
We consider geodesic motions in Kerr–Sen–AdS4 spacetime. We obtain equations of motion for light rays and test particles. Using parametric diagrams, we show some regions where radial and latitudinal geodesic motions are allowed. We analyze the impact of parameters related to the
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We consider geodesic motions in Kerr–Sen–AdS4 spacetime. We obtain equations of motion for light rays and test particles. Using parametric diagrams, we show some regions where radial and latitudinal geodesic motions are allowed. We analyze the impact of parameters related to the dilatonic scalar on the orbit and find that it will result in more rich and complex orbital types.
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(This article belongs to the Section Gravitation)
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Open AccessReview
Transport Coefficients of Relativistic Matter: A Detailed Formalism with a Gross Knowledge of Their Magnitude
by
Ashutosh Dwibedi, Nandita Padhan, Arghya Chatterjee and Sabyasachi Ghosh
Universe 2024, 10(3), 132; https://doi.org/10.3390/universe10030132 - 07 Mar 2024
Abstract
The present review article has attempted a compact formalism description of transport coefficient calculations for relativistic fluid, which is expected in heavy ion collision experiments. Here, we first address the macroscopic description of relativistic fluid dynamics and then its microscopic description based on
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The present review article has attempted a compact formalism description of transport coefficient calculations for relativistic fluid, which is expected in heavy ion collision experiments. Here, we first address the macroscopic description of relativistic fluid dynamics and then its microscopic description based on the kinetic theory framework. We also address different relaxation time approximation-based models in Boltzmann transport equations, which make a sandwich between Macro and Micro frameworks of relativistic fluid dynamics and finally provide different microscopic expressions of transport coefficients like the fluid’s shear viscosity and bulk viscosity. In the numeric part of this review article, we put stress on the two gross components of transport coefficient expressions: relaxation time and thermodynamic phase-space part. Then, we try to tune the relaxation time component to cover earlier theoretical estimations and experimental data-driven estimations for RHIC and LHC matter. By this way of numerical understanding, we provide the final comments on the values of transport coefficients and relaxation time in the context of the (nearly) perfect fluid nature of the RHIC or LHC matter.
Full article
(This article belongs to the Special Issue Exploring Quark Matter under Extreme Scenarios of Temperature and Density)
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Open AccessArticle
On Phase Transitions during Collisions near the Horizon of Black Holes
by
Andrey A. Grib and Yuri V. Pavlov
Universe 2024, 10(3), 131; https://doi.org/10.3390/universe10030131 - 07 Mar 2024
Abstract
During particle collisions in the vicinity of the horizon of black holes, it is possible to achieve energies and temperatures corresponding to phase transitions in particle physics. It is shown that the sizes of the regions of the new phase are of the
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During particle collisions in the vicinity of the horizon of black holes, it is possible to achieve energies and temperatures corresponding to phase transitions in particle physics. It is shown that the sizes of the regions of the new phase are of the order of the Compton length for the corresponding mass scale. The lifetime is also on the order of the Compton time. It is shown that the inverse influence of the energy density in the electro-weak phase transition in collisions on the space–time metric can be neglected.
Full article
(This article belongs to the Special Issue The Friedmann Cosmology: A Century Later)
Open AccessReview
The Modeling of Pulsar Magnetosphere and Radiation
by
Gang Cao, Xiongbang Yang and Li Zhang
Universe 2024, 10(3), 130; https://doi.org/10.3390/universe10030130 - 07 Mar 2024
Abstract
We review the recent advances in the pulsar high-energy -ray observation and the electrodynamics of the pulsar magnetospheres from the early vacuum model to the recent plasma-filled models by numerical simulations. The numerical simulations have made significant progress toward the self-consistent modeling
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We review the recent advances in the pulsar high-energy -ray observation and the electrodynamics of the pulsar magnetospheres from the early vacuum model to the recent plasma-filled models by numerical simulations. The numerical simulations have made significant progress toward the self-consistent modeling of the plasma-filled magnetosphere by including the particle acceleration and radiation. The current numerical simulations confirm a near force-free magnetosphere with the particle acceleration in the separatrix near the light cylinder and the current sheet outside the light cylinder, which can provide a good match to the recent high-energy -ray observations. The modeling of the combined multi-wavelength light curves, spectra, and polarization are expected to provide a stronger constrain on the geometry of the magnetic field lines, the location of the particle acceleration and the emission region, and the emission mechanism in the pulsar magnetospheres.
Full article
(This article belongs to the Special Issue Pulsar Astronomy)
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Open AccessArticle
A Simple Direct Empirical Observation of Systematic Bias of the Redshift as a Distance Indicator
by
Lior Shamir
Universe 2024, 10(3), 129; https://doi.org/10.3390/universe10030129 - 06 Mar 2024
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Recent puzzling observations, such as the tension, large-scale anisotropies, and massive disk galaxies at high redshifts, have been challenging the standard cosmological model. While one possible explanation is that the standard model is incomplete, other theories are based on the contention
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Recent puzzling observations, such as the tension, large-scale anisotropies, and massive disk galaxies at high redshifts, have been challenging the standard cosmological model. While one possible explanation is that the standard model is incomplete, other theories are based on the contention that the redshift model as a distance indicator might be biased. These theories can explain the recent observations, but they are challenged by the absence of a direct empirical reproducible observation that the redshift model can indeed be inconsistent. Here, I describe a simple experiment that shows that the spectra of galaxies depend on their rotational velocity relative to the rotational velocity of the Milky Way. Moreover, it shows that the redshift of galaxies that rotate in the opposite direction relative to the Milky Way is significantly smaller compared with the redshift of galaxies that rotate in the same direction relative to the Milky Way (p < 0.006). Three different datasets were used independently, each one was prepared in a different manner, and all of them showed similar redshift bias. A fourth dataset of galaxies from the Southern Galactic pole was also analyzed and shows similar results. All four datasets are publicly available. While a maximum average z difference of ∼0.012 observed with galaxies of relatively low redshift (z < 0.25) is not extreme, the bias is consistent and canpotentially lead to explanations to puzzling observations such as the tension.
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Open AccessArticle
Re-Examination of the Effect of Pairing Gaps on Gamow–Teller Strength Distributions and β-Decay Rates
by
Jameel-Un Nabi, Muhammad Riaz and Arslan Mehmood
Universe 2024, 10(3), 128; https://doi.org/10.3390/universe10030128 - 06 Mar 2024
Abstract
-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the -decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar
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-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the -decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar -decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of -decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest -decay rates in stellar matter.
Full article
(This article belongs to the Special Issue Recent Advances in Double Beta Decay Investigations: In Honor of Prof. Sabin Stoica at His 70th Anniversary)
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Topical Collection in
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Open Questions in Black Hole Physics
Collection Editors: Gonzalo Olmo, Diego Rubiera-Garcia
Topical Collection in
Universe
Nobel Prize 2020: Selected Articles on Black Hole and General Relativity
Collection Editor: Lorenzo Iorio