Universe

43 pages, 1931 KB

Open AccessArticle

Static Solitons in an Expanding Universe

by Nagabhushana Prabhu

Universe 2026, 12(4), 119; https://doi.org/10.3390/universe12040119 - 20 Apr 2026

Viewed by 404

We show, analytically, that a static sine-Gordon soliton cannot exist in 1 + 1 non-dynamical de Sitter spacetime if

α : = {(m / H)}^{2} < 2

, where m is the mass parameter of the sine-Gordon theory and H [...] Read more.

We show, analytically, that a static sine-Gordon soliton cannot exist in 1 + 1 non-dynamical de Sitter spacetime if

α : = {(m / H)}^{2} < 2

, where m is the mass parameter of the sine-Gordon theory and H is the Hubble constant. Conversely, we also show that static sine-Gordon solitons exist in 1 + 1 non-dynamical de Sitter spacetime if

α > 2

. The above threshold is explained—qualitatively and to within an O(1) factor—using a heuristic argument involving the interplay of tensile force in the Lorentzian sine-Gordon soliton and the tidal force in de Sitter spacetime. A similar heuristic argument, which remains to be confirmed analytically, also suggests the existence of a threshold,

{(m_{V} / H)}^{2} \sim O (1)

, below which the tidal forces are too strong to permit the existence of a static 't Hooft–Polyakov monopole in non-dynamical 3 + 1 de Sitter spacetime;

m_{V}

is the mass of the vector boson. Linde has suggested that new inflation could have triggered secondary inflation at the core of a GUT (Grand Unified Theory) monopole even if the Hubble constant at or after the GUT phase transition was significantly smaller than the mass of the X boson. We present a heuristic argument, which suggests that the

S O (3)

't Hooft–Polyakov monopole does not allow secondary inflation at its core when the inflationary background is weak. Based on the above, as yet analytically unconfirmed, heuristic argument for the

S O (3)

't Hooft–Polyakov monopole, we conjecture that secondary inflation at the core of a GUT monopole, as suggested by Linde, is infeasible. Full article

(This article belongs to the Section Cosmology)

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14 pages, 372 KB

Open AccessArticle

Probing Short-Range Nucleon–Nucleon Correlations by Detecting Spectator Neutrons in Collider Experiments

by Aleksandr Svetlichnyi, Savva Savenkov, Polina Iusupova and Igor Pshenichnov

Universe 2026, 12(4), 118; https://doi.org/10.3390/universe12040118 - 17 Apr 2026

Viewed by 562

Abstract

We investigate whether short-range nucleon–nucleon correlations (NN-SRC) and cluster configurations in nuclei can be explored by studying spectator neutrons produced in high-energy nucleus–nucleus collisions. In particular, we propose to measure the multiplicity distributions of forward spectator neutrons in symmetric ¹²C–¹²C [...] Read more.

We investigate whether short-range nucleon–nucleon correlations (NN-SRC) and cluster configurations in nuclei can be explored by studying spectator neutrons produced in high-energy nucleus–nucleus collisions. In particular, we propose to measure the multiplicity distributions of forward spectator neutrons in symmetric ¹²C–¹²C and ⁴⁰Ca–⁴⁰Ca collisions at

\sqrt{s_{NN}} = 11

GeV with the Spin Physics Detector (SPD) at the NICA facility. To assess this method, we simulate the production of spectator nucleons in these reactions using the Abrasion–Ablation Monte Carlo for Colliders model with MST clustering (AAMCC-MST). Short-range nucleon–nucleon correlations inside ¹²C and ⁴⁰Ca are implemented via a Monte Carlo rejection sampling procedure. Our results indicate that spectator production exhibits only a weak dependence on the specific features of NN-SRC. We also observe that including

α

-cluster configurations in ¹²C leads to a reduction of the average multiplicity of spectator neutrons as a function of collision centrality. Full article

(This article belongs to the Special Issue Relativistic Heavy-Ion Collisions: Theory and Observation)

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17 pages, 1141 KB

Open AccessArticle

Effects of the Symmetry Energy Slope on Magnetized Neutron Stars

by Luiz L. Lopes, César O. V. Flores and Débora Peres Menezes

Universe 2026, 12(4), 117; https://doi.org/10.3390/universe12040117 - 15 Apr 2026

Cited by 1 | Viewed by 530

Abstract

In this work, we study the effect of the symmetry slope on the observables of weakly and strongly magnetized neutron stars within the chaotic magnetic field approximation. We investigate the impact of the symmetry energy slope in the equation of state, as well [...] Read more.

In this work, we study the effect of the symmetry slope on the observables of weakly and strongly magnetized neutron stars within the chaotic magnetic field approximation. We investigate the impact of the symmetry energy slope in the equation of state, as well as on the observables of neutron stars, by calculating their masses, radii, redshifts, tidal deformabilities, and fundamental-mode gravitational-wave frequencies. We show that the effect of the magnetic field is strong on low mass stars, producing a softer equation of state and correspondingly lower values of radii. Furthermore, the magnetic field also causes a significant drop in the dimensionless tidal parameter even when the effects on the radii are small. At the end of the paper, we discuss the effects of the magnetic field on neutron stars’ universal relations. Full article

(This article belongs to the Special Issue Magnetized Dense Matter in Compact Stars: From Fundamental Properties to Astrophysical Observables)

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48 pages, 5383 KB

Open AccessArticle

A Dark Atom Scenario for Direct Dark Matter Investigation

by Pierluigi Belli, Rita Bernabei, Vitaly Beylin, Timur Bikbaev, Artem Kharakhashyan, Maxim Khlopov, Vladimir Korchagin, Andrey Mayorov and Danila Sopin

Universe 2026, 12(4), 116; https://doi.org/10.3390/universe12040116 - 15 Apr 2026

Viewed by 1093

Abstract

This paper extensively explores the concept of dark atoms, hypothetical stable lepton-like particles with a charge of

- 2 n

(where n is any natural number) that form neutral bound states with n primordial helium nuclei. The discussion begins with the introduction of [...] Read more.

This paper extensively explores the concept of dark atoms, hypothetical stable lepton-like particles with a charge of

- 2 n

(where n is any natural number) that form neutral bound states with n primordial helium nuclei. The discussion begins with the introduction of multiply charged stable particles. Next, the formation and evolution of dark atoms are examined, followed by a review of related constraints. The capture of dark atoms by the Earth and implications for direct dark matter search are subsequently discussed. Then, the quantum-mechanical description of bound states between dark atoms and ordinary nuclei is addressed. Moreover, procedures for systematic comparisons with this model, which have general interest, are presented considering the DAMA published results on the dark matter annual and diurnal modulation signatures as a benchmark. Full article

(This article belongs to the Topic Dark Matter, Dark Energy and Cosmological Anisotropy)

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16 pages, 276 KB

Open AccessPerspective

Cosmic Illuminating Gift: A One-Way Information Box for Extraterrestrial Intelligences

by Arman Shafieloo

Universe 2026, 12(4), 115; https://doi.org/10.3390/universe12040115 - 14 Apr 2026

Viewed by 1331

Abstract

We introduce the concept of a one-way, broadband information package, the Cosmic Illuminating Gift, intended to provide distant intelligences with fundamental empirical data about the Universe. Unlike previous messaging to extraterrestrial intelligences (METI) that emphasized greetings or cultural identity, the Gift aims [...] Read more.

We introduce the concept of a one-way, broadband information package, the Cosmic Illuminating Gift, intended to provide distant intelligences with fundamental empirical data about the Universe. Unlike previous messaging to extraterrestrial intelligences (METI) that emphasized greetings or cultural identity, the Gift aims to transmit unbiased, universally interpretable information that recipients could not otherwise obtain due to their distinct spacetime position and epoch. By emphasizing raw observations, rather than human interpretations or cosmological models, the Gift aspires to serve as a neutral and enduring resource. A central assumption of the project is that any potential recipients are likely to possess a level of intelligence and technological sophistication far beyond our own. Accordingly, the content and encoding of the Gift are not designed to “teach” fundamentals, but to deliver compact, logically structured packets that such civilizations could decode even at extremely low signal-to-noise levels. This perspective shifts the challenge from brute-force transmission to ensuring that photons arrive in spectrally quiet windows and that the format is unmistakably artificial and distinguishable from astrophysical backgrounds. We outline strategies for content selection, encoding, and transmission that reflect this assumption. Practical implementation is feasible with current or near-term infrastructure, and future advances will only improve the quality of subsequent Gifts. Ultimately, the endeavor is unique among scientific projects in that it anticipates no feedback or measurable result within the span of our civilization’s timeline. Its significance lies instead in the act of contribution itself: offering a durable, universal dataset as a gesture of intellectual solidarity across cosmic distances. Full article

(This article belongs to the Section Cosmology)

18 pages, 819 KB

Open AccessArticle

Jacobi Stability of Circular Orbits Around Conformally Invariant Weyl Gravity Black Holes

by Cristina Blaga and Paul A. Blaga

Universe 2026, 12(4), 114; https://doi.org/10.3390/universe12040114 - 14 Apr 2026

Viewed by 437

Abstract

Weyl conformal gravity was originally proposed in the early twentieth century as an attempt to unify gravitation and electromagnetism. Since 1989, renewed interest in this fourth-order theory of gravity has emerged following the discovery of several exact black hole solutions. In this work, [...] Read more.

Weyl conformal gravity was originally proposed in the early twentieth century as an attempt to unify gravitation and electromagnetism. Since 1989, renewed interest in this fourth-order theory of gravity has emerged following the discovery of several exact black hole solutions. In this work, we investigate the timelike circular geodesics of a spherically symmetric Weyl black hole. The effective potential, the circular geodesics and their Jacobi and Lyapunov stability are discussed. Our analysis provides new insights into the stability properties of Weyl black holes and the role of the free parameters appearing in their solutions. Full article

(This article belongs to the Special Issue BGL2025: The 13th Bolyai–Gauss–Lobachevsky Conference on Non-Euclidean Geometry and Its Applications)

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7 pages, 909 KB

Open AccessCommunication

Dyson Spheres on H–R Diagram

by Amirnezam Amiri

Universe 2026, 12(4), 113; https://doi.org/10.3390/universe12040113 - 14 Apr 2026

Viewed by 1030

Abstract

The construction of Dyson spheres, megastructures designed to capture the total radiative output of stars, can be one of the most compelling techno-signature scenarios for advanced extraterrestrial civilizations. By considering equilibrium temperatures, we investigate the luminosities and fluxes of Dyson spheres built around [...] Read more.

The construction of Dyson spheres, megastructures designed to capture the total radiative output of stars, can be one of the most compelling techno-signature scenarios for advanced extraterrestrial civilizations. By considering equilibrium temperatures, we investigate the luminosities and fluxes of Dyson spheres built around two promising classes of host stars: white dwarfs and red M-dwarfs. Using radiative balance arguments and representative stellar parameters, we compute the temperature–radius relationship for full energy interception and place these hypothetical structures on the Hertzsprung–Russell (H–R) diagram to assess their observational signatures. Our results show that Dyson spheres around white dwarfs produce cooler and fainter blackbody emissions, peaking in the near- to mid-infrared, while those around M-dwarfs radiate more strongly but at longer wavelengths. In both cases, the equilibrium temperature decreases as

R_{D}^{- 1 / 2}

, while the total luminosity and observed bolometric flux remain fixed by the stellar output. These findings highlight the astrophysical suitability of low-luminosity stars as Dyson sphere hosts and provide practical constraints for future techno-signature searches using infrared surveys. Full article

(This article belongs to the Section Solar and Stellar Physics)

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24 pages, 2466 KB

Open AccessArticle

Classification of Symmetric Four-Body Dziobek Central Configurations and Application to the Earth–Moon System

by Zalán Czirják, Bálint Érdi and Emese Forgács-Dajka

Universe 2026, 12(4), 112; https://doi.org/10.3390/universe12040112 - 10 Apr 2026

Viewed by 752

Abstract

Central configurations are fundamental equilibrium solutions of the Newtonian n-body problem and play a key role in understanding the structure and dynamics of gravitational systems. However, the classification and enumeration of such configurations remain incomplete in the four-body case, particularly for symmetric [...] Read more.

Central configurations are fundamental equilibrium solutions of the Newtonian n-body problem and play a key role in understanding the structure and dynamics of gravitational systems. However, the classification and enumeration of such configurations remain incomplete in the four-body case, particularly for symmetric configurations. In this work, we develop a framework for determining and classifying symmetric four-body Dziobek configurations. The method allows the explicit determination of the number of admissible configurations directly from the mass parameters, without requiring prior knowledge of their geometric structure. Combined with previously established semi-analytical relations, this approach provides a systematic characterization of symmetric configurations in terms of mass ratios. As a physically relevant application, we apply the framework to the Earth–Moon system and determine the possible symmetric four-body central configurations involving Earth- and Moon-mass bodies and an additional object of arbitrary mass. We identify both isolated configurations and continuous families of equilibrium solutions, extending the concept of libration points to the four-body problem. The presented semi-analytical approach contributes to the understanding of equilibrium structures in multi-body gravitational systems and provides a foundation for further studies in celestial mechanics, planetary dynamics, and spacecraft motion in complex gravitational environments. Full article

(This article belongs to the Section Planetary Sciences)

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18 pages, 357 KB

Open AccessArticle

Local Feynman Diagrammatics in Curved Spacetime: A Consistent LMC Framework

by Fridolin Weber

Universe 2026, 12(4), 111; https://doi.org/10.3390/universe12040111 - 10 Apr 2026

Viewed by 496

Abstract

We develop a general framework for quantum field theory in curved spacetime based on Local Minkowski Coordinates (LMC), which incorporates curvature effects into local Feynman diagrammatics. Gravitational influence enters through a curvature-dependent normalization function

B (x)

, derived from covariant current [...] Read more.

We develop a general framework for quantum field theory in curved spacetime based on Local Minkowski Coordinates (LMC), which incorporates curvature effects into local Feynman diagrammatics. Gravitational influence enters through a curvature-dependent normalization function

B (x)

, derived from covariant current conservation, and a gravitational phase

S (x)

, obtained via the WKB approximation. These quantities enter through local phase accumulation and observer-dependent normalization of external states, without modifying globally conserved fluxes. As a first application, we analyze the local redshift normalization and phase structure of quantum amplitudes in the vicinity of a Schwarzschild black hole. Within their range of validity, the curvature-dependent factors

B (x)

and

S (x)

reproduce the expected gravitational redshift of field amplitudes in general relativity. When amplitudes are propagated to asymptotic infinity and evaluated in a standard global quantum state (such as the Unruh state), the resulting flux is consistent with the standard Hawking result. The framework refines the local WKB structure and clarifies the separation between local normalization effects and globally conserved fluxes. Full article

(This article belongs to the Special Issue Quantum Field Theory in Curved Spacetime and Its Implications for Cosmology, Blackholes and Quantum Gravity, 2nd Edition)

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23 pages, 340 KB

Open AccessArticle

Linear Perturbations of an Exact Gravitational Wave in the Bianchi IV Universe

by Konstantin Osetrin

Universe 2026, 12(4), 110; https://doi.org/10.3390/universe12040110 - 9 Apr 2026

Viewed by 380

Abstract

The proper-time method for constructing perturbative dynamical gravitational fields is presented. Using the proper-time method, a perturbative analytical model of gravitational waves against the backdrop of an exact wave solution of Einstein’s equations in a Bianchi IV universe is constructed. To construct the [...] Read more.

The proper-time method for constructing perturbative dynamical gravitational fields is presented. Using the proper-time method, a perturbative analytical model of gravitational waves against the backdrop of an exact wave solution of Einstein’s equations in a Bianchi IV universe is constructed. To construct the perturbative analytical wave model a privileged wave coordinate system and a synchronous time function associated with the proper time of an observer freely moving in a gravitational wave are used. Reduction of the field equations, taking into account compatibility conditions, reduces the mathematical model of gravitational waves to a system of coupled ordinary differential equations for functions of the wave variable. Analytical solutions for the components of the gravitational wave metric have been found. The stability of the resulting perturbative solutions for the continuum domain of parameters is proven. The linear stability of the exact solution for a gravitational wave in the anisotropic Bianchi IV universe for the continuum domain of parameters is demonstrated. Full article

(This article belongs to the Special Issue Theoretical Physics and Cosmology: A Themed Issue in Honor of Professor Emilio Elizalde on the Occasion of His 75th Birthday)

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12 pages, 335 KB

Open AccessCommunication

Radiative Corrections to the Nucleon Isovector g_V and g_A

by Oleksandr Tomalak and Yi-Bo Yang

Universe 2026, 12(4), 109; https://doi.org/10.3390/universe12040109 - 9 Apr 2026

Cited by 3 | Viewed by 446

Abstract

Electroweak, QCD, and QED radiative corrections to the nucleon low-energy coupling constants

g_{V}

and

g_{A}

are enhanced by large perturbative logarithms between the electroweak and hadronic scale, as well as between the hadronic scale and the low-energy MeV scale. Additionally, higher-order [...] Read more.

Electroweak, QCD, and QED radiative corrections to the nucleon low-energy coupling constants

g_{V}

and

g_{A}

are enhanced by large perturbative logarithms between the electroweak and hadronic scale, as well as between the hadronic scale and the low-energy MeV scale. Additionally, higher-order pion-mass splitting corrections to the nucleon axial-vector charge might be large. By consistently incorporating these effects, we provide an updated relation between the lattice-QCD and physical

g_{A}

, finding a total radiative correction of

3.5 (2.1) %

(

5.6 (0.7) %

). This leads to an expected lattice-QCD result of

g_{A}^{QCD} = 1.265 (26)

(

g_{A}^{QCD} = 1.240 (9)

) when based on a combination of lattice-QCD and data-driven (or only data-driven) inputs, respectively. Future phenomenological, chiral perturbation theory, and lattice-QCD studies can improve both the central value and the uncertainty of this estimate. Full article

(This article belongs to the Special Issue Neutrino Oscillations and Interactions)

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7 pages, 743 KB

Open AccessArticle

Misaligned Rings Around Minor Planets with Moons

by Barnabás Deme

Universe 2026, 12(4), 108; https://doi.org/10.3390/universe12040108 - 9 Apr 2026

Viewed by 387

Abstract

Recent observations have confirmed the existence of rings around minor bodies in the outer solar system. These objects may possess satellites as well. Here, we analytically investigate the interaction between such rings and satellites. We show that the perturbations from the moons may [...] Read more.

Recent observations have confirmed the existence of rings around minor bodies in the outer solar system. These objects may possess satellites as well. Here, we analytically investigate the interaction between such rings and satellites. We show that the perturbations from the moons may efficiently lead to off-equatorial rings around minor bodies like trans-neptunian objects or centaurs. In particular, we derive criteria for the orbital elements under which such misaligned rings may exist. These considerations will be easily testable with the upcoming deep sky surveys. Full article

(This article belongs to the Special Issue The Hidden Stories of Small Planetary Bodies)

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36 pages, 11979 KB

Open AccessArticle

A Few Years Later: Revisiting Period Variations of Eclipsing Binaries in the Northern Continuous Viewing Zone of TESS

by Tamás Borkovits, Tibor Mitnyan, Donát R. Czavalinga and Saul A. Rappaport

Universe 2026, 12(4), 107; https://doi.org/10.3390/universe12040107 - 3 Apr 2026

Viewed by 1323

Abstract

In our previous analysis of the eclipse timing variation patterns of eclipsing binaries located in and near the Northern Continuous Viewing Zone (NCVZ) of the TESS space telescope, 135 hierarchical triple star candidates were found. Now, two additional years of TESS observations are [...] Read more.

In our previous analysis of the eclipse timing variation patterns of eclipsing binaries located in and near the Northern Continuous Viewing Zone (NCVZ) of the TESS space telescope, 135 hierarchical triple star candidates were found. Now, two additional years of TESS observations are available and, hence, we have extended the former analysis with the use of the new observational data. We now detect 168 triple star candidates in the updated and reanalyzed sample. The majority (∼74%) of them are identical to the former triples candidates. For many of them, our new solutions are more certain than the original ones. Therefore, we can now conclude that we have identified at least 66 short-period hierarchical triple stellar systems in the NCVZ with full confidence. In the case of the majority of the remaining systems in our sample, the presence of a close third stellar component appears to be very likely. We also identify additional, longer timescale period variations in 34 systems (20% of the total sample) and conclude that in at least three systems the presence of a fourth stellar component is quite plausible. Finally, we report the complete disappearance of the eclipses in two former EBs and detect eclipse depth variations in seven other EBs as well. We interpret this effect as the consequence of changing orbital inclination caused by a non-coplanar third body. Full article

(This article belongs to the Special Issue The Royal Road: Eclipsing Binaries and Transiting Exoplanets, 2nd Edition)

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44 pages, 6786 KB

Open AccessReview

Cavity, Lumped Circuit, and Spin-Based Detection of Axion Dark Matter: Differences and Similarities

by Deniz Aybas, Hendrik Bekker, Dmitry Budker, Wei Ji, On Kim, Younggeun Kim, Derek F. Jackson Kimball, Jia Liu, Xiaolin Ma, Chiara P. Salemi, Yannis K. Semertzidis, Alexander O. Sushkov, Kai Wei, Arne Wickenbrock and Yuzhe Zhang

Universe 2026, 12(4), 106; https://doi.org/10.3390/universe12040106 - 3 Apr 2026

Cited by 1 | Viewed by 1817

Abstract

Axions and axion-like particles are compelling candidates for ultralight bosonic dark matter, forming coherent oscillating fields that can be probed by experiments known as haloscopes. A broad range of haloscope concepts has been developed, including resonant cavity haloscopes, lumped-element circuit detectors, and spin-based [...] Read more.

Axions and axion-like particles are compelling candidates for ultralight bosonic dark matter, forming coherent oscillating fields that can be probed by experiments known as haloscopes. A broad range of haloscope concepts has been developed, including resonant cavity haloscopes, lumped-element circuit detectors, and spin-based experiments, each sensitive to different axion couplings and mass ranges. Rather than attempting an exhaustive survey of all existing approaches, this comparative review provides a unified framework for the major haloscope classes, establishing a common language for the descriptions of signal generation, noise properties, analytical methodologies, and scanning strategies. Key properties of ultralight bosonic dark matter relevant for detection are summarized first, including coherence time, spectral linewidth, and stochasticity under the standard halo model. The discussion then compares cavity, Earth-scale, lumped-element, and spin haloscopes, focusing on expected signal shapes, dominant noise sources, and statistical frameworks for axion searches. Particular emphasis is placed on consistent definitions of signal-to-noise ratio and on how detector bandwidth, axion coherence, and noise characteristics determine optimal scan strategies. By systematically comparing operating principles and performance metrics across these detector families, this framework clarifies shared concepts as well as the essential differences that govern sensitivity in different mass and coupling regimes. The resulting perspective synthesizes current search methodologies and offers guidance for optimizing future haloscope experiments. Full article

(This article belongs to the Special Issue Ultralight Bosonic Dark Matter: Theoretical Developments and Experimental Searches)

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17 pages, 2951 KB

Open AccessArticle

Probing Signatures of Sterile Neutrinos in the MOMENT and DUNE Experiments

by Sambit Kumar Pusty, Pratham Jiwani, Rudra Majhi and Rukmani Mohanta

Universe 2026, 12(4), 105; https://doi.org/10.3390/universe12040105 - 2 Apr 2026

Viewed by 521

Abstract

Motivated by the persistent short-baseline anomalies that hint at the possible existence of physics beyond the standard three-flavor paradigm, we study the phenomenology of light sterile neutrinos in the minimal (3 + 1) framework using two future experiments: the MuOn-decay MEdium-baseline NeuTrino beam [...] Read more.

Motivated by the persistent short-baseline anomalies that hint at the possible existence of physics beyond the standard three-flavor paradigm, we study the phenomenology of light sterile neutrinos in the minimal (3 + 1) framework using two future experiments: the MuOn-decay MEdium-baseline NeuTrino beam experiment (MOMENT) and the Deep Underground Neutrino Experiment (DUNE). We place constraints on active–sterile mixing parameters, probe CP-violation discovery potential, and examine correlations between the standard Dirac CP phase and the additional CP phases arising from active–sterile mixing to quantify phase degeneracies. We present exclusion limits and demonstrate the crucial role of the near detector in improving sensitivities by one or two orders of magnitude compared to a configuration with only the far detector. We find that the presence of sterile neutrinos can reduce the CP-violation sensitivity in long-baseline neutrino oscillation experiments. For large sterile mass splittings, the rapid oscillations average out, leading to strong parameter degeneracies in DUNE. In contrast, MOMENT retains strong sensitivity to CP violation and efficiently disentangles the standard and sterile CP phases. Our results highlight the strong complementarity between DUNE and MOMENT and show that their combined capabilities provide a powerful test of the light sterile neutrino hypothesis in regions of the parameter space that remain weakly constrained by current data. Full article

(This article belongs to the Special Issue Neutrino Oscillations and Interactions)

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11 pages, 906 KB

Open AccessArticle

Optical Variability and Evidence for a Changing-Look Event in the Galaxy Mrk 6 (IC 450)

by Saule Shomshekova, Gaukhar Aimanova, Nazim Huseynov, Ayazhan Temirzhanova, Diana Nasirova, Inna Reva, Daulet Anarbek and Alexander Serebryanskiy

Universe 2026, 12(4), 104; https://doi.org/10.3390/universe12040104 - 2 Apr 2026

Viewed by 610

Abstract

In this work, the light curve of the Seyfert galaxy Mrk 6 constructed from photometric observations in the B, V, and

R_{c}

filters over the period from 5 April 2016 to 1 February 2026 is presented and analyzed. Over the [...] Read more.

In this work, the light curve of the Seyfert galaxy Mrk 6 constructed from photometric observations in the B, V, and

R_{c}

filters over the period from 5 April 2016 to 1 February 2026 is presented and analyzed. Over the entire monitoring interval (2016–2026), the variability amplitude of the light curve reaches

Δ B = 1.9

mag,

Δ V = 1.5

mag, and

Δ R_{c} = 1.4

mag. During 2024–2026, the galaxy exhibits synchronous photometric variability in the B, V, and

R_{c}

filters with an amplitude of ∼0.3 mag. The study also uses spectroscopic observations obtained on 15 and 22 November 2025 and 16 February 2026 at the Shamakhy Astrophysical Observatory (Azerbaijan), as well as on 9 January 2026 at the Fesenkov Astrophysical Institute (Kazakhstan). The fluxes in the H

β

emission line were calibrated using the [O III]

λ 5007

Å line, ensuring consistent relative calibration of the spectral data. A comparison of the optical spectra reveals a pronounced transformation of the H

β

line profile between November 2025 and January 2026. The broad component, clearly present in November 2025, becomes strongly suppressed and nearly disappears in January 2026, while the narrow emission lines remain stable. This behavior is consistent with a changing-look transition, indicating a temporary weakening of the broad-line region emission. The radius of the broad-line region

R_{BLR}

was taken to be equal to the average time delays (lags), amounting to ≈20 light days for the H

β

emission and ≈28 light days for the H

α

. Full article

(This article belongs to the Special Issue Seyfert Galaxies: Probing the Active Nuclei of Nearby Galaxies)

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18 pages, 1010 KB

Open AccessArticle

Dynamics of a Classical Bi-Metric Cosmology with GUP-Deformed Poisson Brackets

by Diego Castillo and Fernando Méndez

Universe 2026, 12(4), 103; https://doi.org/10.3390/universe12040103 - 2 Apr 2026

Viewed by 1059

Abstract

This work analyzes a bi-metric cosmological model where two sectors, characterized by their respective scale factors, interact through a deformed Poisson bracket structure. This deformation is based on the Generalized Uncertainty Principle (GUP). Through a numerical analysis, we study how this interaction affects [...] Read more.

This work analyzes a bi-metric cosmological model where two sectors, characterized by their respective scale factors, interact through a deformed Poisson bracket structure. This deformation is based on the Generalized Uncertainty Principle (GUP). Through a numerical analysis, we study how this interaction affects the expansion dynamics. The results indicate that for positive values of the deformation parameter, the coupling induces an acceleration that leads to a Big Rip singularity in finite time, even in the absence of a cosmological constant. A power-law relation is established between the deformation parameter and the critical time of divergence for the scale factors. Finally, the regime with a negative deformation parameter is also investigated. In this case, the symplectic structure becomes singular, leading to the contraction of one sector and the freezing of the other. Full article

(This article belongs to the Section Cosmology)

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21 pages, 4199 KB

Open AccessArticle

Using Electrodynamic Tethers to Create Artificial Sun-Synchronous Orbits and De-Orbit Remote Sensing Satellites

by Antonio F. B. A. Prado and Vladimir Razoumny

Universe 2026, 12(4), 102; https://doi.org/10.3390/universe12040102 - 2 Apr 2026

Viewed by 569

Abstract

This paper has the goal of exploring the potential of electromagnetic propulsion systems based on tethers to create artificial Sun-synchronous orbits for remote sensing satellites, as well as performing station-keeping maneuvers and de-orbiting of the satellite after the end of its useful life. [...] Read more.

This paper has the goal of exploring the potential of electromagnetic propulsion systems based on tethers to create artificial Sun-synchronous orbits for remote sensing satellites, as well as performing station-keeping maneuvers and de-orbiting of the satellite after the end of its useful life. To create artificial Sun-synchronous orbits, the force is applied to keep the longitude of the ascending node with the same angular velocity of the apparent motion of the Sun around the Earth, which is the definition of a Sun-synchronous orbit. These orbits are very important for remote sensing satellites, because in these orbits the satellite passes by a given point at the same time, helping in analyzing the data collected. The use of electrodynamic tethers can extend the regions of Sun-synchronous orbits, both in terms of inclination and semi-major axis. To perform the de-orbiting of the satellite, the same tether can apply a force in the opposite direction of the motion of the satellite, so reducing its energy and decreasing the semi-major axis until the satellite crashes into the atmosphere of the Earth. This is very important to avoid increasing the presence of space debris in space, a very serious problem nowadays. For the station-keeping maneuvers, we just need to use the appropriate control laws, from time to time, to correct any errors in the Keplerian elements. A significant advantage of employing an electrodynamic tether over traditional thrusters is that it does not require consumption of fuel. The study assumes that a current can flow in both directions through the tether, so interacting with the magnetic field of the Earth to create the Lorentz force. The possibility of using electrodynamic tethers with autonomous charge generation, to avoid dependence on plasma densities and other external factors, is considered. The results presented here help in space and planetary science, since they give more options for remote sensing satellites, which are a key element in planetary science. Full article

(This article belongs to the Topic Techniques and Science Exploitations for Earth Observation and Planetary Exploration-2nd Edition)

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23 pages, 2936 KB

Open AccessArticle

Lightweight Transient-Source Detection Method for Edge Computing

by Jiahao Zhang, Yutian Fu, Feng Dong and Lingfeng Huang

Universe 2026, 12(4), 101; https://doi.org/10.3390/universe12040101 - 1 Apr 2026

Viewed by 625

Abstract

Transient-source detection without relying on difference images still faces challenges in achieving high accuracy, especially under practical space-based astronomical survey conditions where the data volume is enormous, on-orbit transmission bandwidth is limited, and real-time response is required for rapid follow-up observations. To address [...] Read more.

Transient-source detection without relying on difference images still faces challenges in achieving high accuracy, especially under practical space-based astronomical survey conditions where the data volume is enormous, on-orbit transmission bandwidth is limited, and real-time response is required for rapid follow-up observations. To address these issues, this paper proposes a lightweight detection network that integrates multi-scale feature fusion with contextual feature extraction, enabling efficient real-time processing on resource-constrained edge devices. The proposed model enhances robustness to point-spread-function variations across observation conditions and to complex background environments, while simultaneously improving detection accuracy. To evaluate performance comprehensively, lightweight VGG and lightweight ResNet architectures and other baseline models—commonly used as baselines for transient-source detection—are adopted for comparison. Experimental results show that under the condition that the models have approximately the same number of parameters, the proposed network achieves the best accuracy, obtaining nearly 1% improvement compared with the best-performing baseline model. Based on this design, an ultra-lightweight version with only 7k parameters is further developed by incorporating a compact multi-scale module, improving accuracy by 1% over the version without the multi-scale structure. Moreover, through heterogeneous knowledge distillation and adaptive iterative training, the accuracy of the ultra-lightweight model is further increased from 93.3% to 94.0%. Finally, the model is deployed and validated on an AI hardware acceleration platform. The results demonstrate that the proposed method substantially improves inference throughput while maintaining high accuracy, providing a practical solution for real-time, low-latency, on-device transient-source detection under large data volume and limited transmission conditions. Specifically, the proposed models are trained offline on a high-performance GPU and subsequently deployed on the Fudan Microelectronics 7100 AI board to evaluate their real-world inference efficiency on resource-constrained edge devices. Full article

(This article belongs to the Special Issue Applications of Artificial Intelligence in Modern Astronomy)

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15 pages, 1475 KB

Open AccessArticle

Galactic Core–Tail Structure in BEC Dark Matter with Kapitza Potential

by Itauany Barroso and Hermano Velten

Universe 2026, 12(4), 99; https://doi.org/10.3390/universe12040099 - 31 Mar 2026

Viewed by 495

Abstract

Recently, the experimental realization of a Kapitza potential in a Bose–Einstein condensate (BEC) was reported for the first time in the literature, motivating further theoretical investigations of such a system. At the same time, in the astrophysical context, BEC dark matter models have [...] Read more.

Recently, the experimental realization of a Kapitza potential in a Bose–Einstein condensate (BEC) was reported for the first time in the literature, motivating further theoretical investigations of such a system. At the same time, in the astrophysical context, BEC dark matter models have been widely studied as a possible phenomenological explanation for the dark matter phenomena. We model the galactic structure with an inner cored profile obtained from the ground state equilibrium solution of the Schrödinger–Poisson together with a Kapitza–BEC-like interaction for the tail region. We find reasonable agreement of the model with representative galaxy rotation curves available in the SPARC catalogue. Full article

(This article belongs to the Section Galaxies and Clusters)

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8 pages, 249 KB

Open AccessEditorial

Editorial to the Special Issue “Origins and Natures of Inflation, Dark Matter and Dark Energy, 2nd Edition”

by Kazuharu Bamba

Universe 2026, 12(4), 98; https://doi.org/10.3390/universe12040098 - 31 Mar 2026

Viewed by 655

Abstract

It has been confirmed from recent precise cosmological observations, such as Supernovae Ia (SNe Ia) [...] Full article

(This article belongs to the Special Issue Origins and Natures of Inflation, Dark Matter and Dark Energy, 2nd Edition)

34 pages, 556 KB

Open AccessArticle

Finsler-Randers-Bianchi Type-V Cosmological Model and Modified

f (R, T)

Gravity in Lyra Geometry

by Sachin Kumar, Praduman Kumar Dwivedi, Chayan Kumar Mishra, Ioannis Ampazis and Panayiotis C. Stavrinos

Universe 2026, 12(4), 100; https://doi.org/10.3390/universe12040100 - 31 Mar 2026

Viewed by 974

Abstract

In this research paper, we investigate a Finsler-Randers spacetime in the context of a Bianchi type-V model of universe within the framework of Lyra geometry, employing a modified

f (R, T)

gravity theory that incorporates a cosmological constant

Λ

[...] Read more.

In this research paper, we investigate a Finsler-Randers spacetime in the context of a Bianchi type-V model of universe within the framework of Lyra geometry, employing a modified

f (R, T)

gravity theory that incorporates a cosmological constant

Λ

. We have derived the corresponding anisotropic Friedmann equations for the Finsler–Randers Bianchi type-V model of universe with modified

f (R, T)

gravity in Lyra geometry, including the contributions of the cosmological constant and Randers anisotropic terms

b_{0} (t)

and obtained analytical solutions. Further, we have examined the behavior of various dynamical parameters, commonly used in cosmological analysis, both geometrical and graphical interpretations have been provided. Furthermore, we have derived the Raychaudhuri equation in terms of the cosmological constant as a function of the cosmic time t. Our analysis reveals that the shear scalar

σ^{2}

and the scalar expansion

θ

decrease with cosmic time and tend to zero at late times, indicating the isotropization of the universe in the presence of the cosmological constant; however, the Hubble parameter approaches a constant value rather than vanishing, while the energy density

ρ

, pressure

P

, and the Lyra gauge function

β

remain finite and non-zero even at large cosmic times. Ultimately, we conclude that the universe described by this framework exhibits continuous acceleration, as indicated by the negative value of the deceleration parameter q. Full article

(This article belongs to the Special Issue Celebrating the 110th Anniversary of General Relativity: Advances, Challenges and Perspectives)

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14 pages, 5346 KB

Open AccessArticle

Constraining the Quantum Gravity Energy Scale via Gamma-Ray Burst Spectral Lag Data

by Jia-Wei Jiang, Liang Li and Yu Wang

Universe 2026, 12(4), 97; https://doi.org/10.3390/universe12040097 - 30 Mar 2026

Viewed by 841

Abstract

Lorentz invariance violation (LIV) can alter the group velocity of photons by modifying their dispersion relation, manifesting as differences in the arrival times of photons with different energies. This effect can accumulate over long propagation distances, making gamma-ray bursts (GRBs) a key tool [...] Read more.

Lorentz invariance violation (LIV) can alter the group velocity of photons by modifying their dispersion relation, manifesting as differences in the arrival times of photons with different energies. This effect can accumulate over long propagation distances, making gamma-ray bursts (GRBs) a key tool for probing Lorentz invariance violation. By analyzing spectral lag data from 360 measurements across 90 GRBs using Markov Chain Monte Carlo (MCMC) sampling, and under the assumption that all GRBs share a common intrinsic time delay function, we report a maximum a posteriori value of the energy scale of quantum gravity at linear order

E_{Q G} = 8.96 \times 10^{14}

GeV, though the data are also compatible with Lorentz invariance (

E_{QG} = \infty

) to within

2.8 σ

. Furthermore, we are

95 %

confident that

E_{Q G} \geq 6.67 \times 10^{14}

GeV. Full article

(This article belongs to the Special Issue Gamma-Ray Bursts: Unveiling the Mysteries of the Universe’s Most Powerful Explosions)

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20 pages, 2013 KB

Open AccessArticle

Thermodynamic Properties and Shadow of a New, Improved Schwarzschild Black Hole in the Infrared Limit

by Celio Rodrigues Muniz, Jonathan Alves Rebouças, Francisco Bento Lustosa, Francisco Tiago Barboza Sampaio and Leonardo Tavares de Oliveira

Universe 2026, 12(4), 96; https://doi.org/10.3390/universe12040096 - 28 Mar 2026

Viewed by 496

Abstract

In this work, we propose a modified Schwarzschild geometry inspired by the Asymptotic Safety approach to quantum gravity, in which the Newtonian coupling becomes a running quantity depending on the radial coordinate. We employ an infrared cutoff at the proper distance and obtain [...] Read more.

In this work, we propose a modified Schwarzschild geometry inspired by the Asymptotic Safety approach to quantum gravity, in which the Newtonian coupling becomes a running quantity depending on the radial coordinate. We employ an infrared cutoff at the proper distance and obtain a new quantum-corrected black hole metric. We provide a thermodynamical analysis, first using standard methods and then proceeding to a geometrothermodynamical study of the phase space and to a topological analysis of phase transitions. We also calculate the grey-body factors of our solution, providing exact lower bounds in the quantum-corrected transmission coefficients. Finally, we present the shadow size and intensity profile of our solution, showing its consistency with current observational constraints. Full article

(This article belongs to the Special Issue Exploring and Constraining Alternative Theories of Gravity)

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36 pages, 451 KB

Open AccessArticle

The Thermodynamics of Transient Trapped Surfaces in the Geon Collapse

by Claes Cramer

Universe 2026, 12(4), 95; https://doi.org/10.3390/universe12040095 - 27 Mar 2026

Viewed by 1223

Abstract

It is shown that transient trapped surfaces form in a class of emerging globally hyperbolic spacetimes, within punctured Planck-scale neighbourhoods of the geon supported on intersecting singular supports whose intersection forms a characteristic core in a non-strongly causal setting. These neighbourhoods shrink towards [...] Read more.

It is shown that transient trapped surfaces form in a class of emerging globally hyperbolic spacetimes, within punctured Planck-scale neighbourhoods of the geon supported on intersecting singular supports whose intersection forms a characteristic core in a non-strongly causal setting. These neighbourhoods shrink towards the intersecting singular support in the distributional geometry. In particular, the trapped surfaces occur near the characteristic limit corresponding to the unstable equilibrium of the self-gravitating geon. They act as an effective classical barrier for descriptions formulated purely within smooth differential geometry. The area of these trapped-surface configurations, computed on Planck-referenced neighbourhoods, is shown to tend to zero both in the asymptotically flat limit of the emerging spacetime and in the geon limit. Thus, transient trapped surfaces evaporate in the sense that their area vanishes as classical and asymptotically flat spacetime emerges within the quantum foam framework. A state-counting generating function for the transient trapped surfaces is constructed from the coherent-state density operator. This generating function maps microscopic occupation-number sectors to macroscopic data and thereby allows a definition of Boltzmann entropy (not to be confused with the von Neumann entropy, which is zero for any pure coherent state). Since the coherent state is constructed to implement the correspondence principle, expectation values of the relevant quantised observables reproduce their classical values. In particular, the expectation value of the bosonic occupation-number operator serves as a microstate-counting variable in the coherent sector. The generating function takes the form of an exponential of this expectation value, leading to an entropy–area relation consistent with the Hawking–Bekenstein scaling. Full article

(This article belongs to the Special Issue Quantum Field Theory in Curved Spacetime and Its Implications for Cosmology, Blackholes and Quantum Gravity, 2nd Edition)

37 pages, 4406 KB

Open AccessArticle

The ‘Forgotten’ Neutrons: Implications for the Propagation of High-Energy Cosmic Rays in Magnetized Astrophysical and Cosmological Structures

by Ellis R. Owen, Kinwah Wu, Yoshiyuki Inoue, Tatsuki Fujiwara, Qin Han and Hayden P. H. Ng

Universe 2026, 12(4), 94; https://doi.org/10.3390/universe12040094 - 26 Mar 2026

Viewed by 926

Abstract

Cosmological filaments, galaxy clusters, and galaxies are magnetized reservoirs of cosmic rays (CRs). The exchange of CRs across these structures is usually modeled assuming that they remain charged and magnetically confined. At high energies, hadronic interactions can convert CR protons to neutrons. This [...] Read more.

Cosmological filaments, galaxy clusters, and galaxies are magnetized reservoirs of cosmic rays (CRs). The exchange of CRs across these structures is usually modeled assuming that they remain charged and magnetically confined. At high energies, hadronic interactions can convert CR protons to neutrons. This physics is routinely included in air-shower and ultra-high-energy (UHE) CR propagation Monte Carlo simulations used for composition studies but is rarely treated explicitly in propagation models of CR transport and exchange between magnetized reservoirs. CR neutrons are not affected by magnetic fields and can propagate ballistically over kpc-Mpc distances before decaying back into protons, with relativistic time dilation extending their effective decay length. We show how such charged–neutral switching modifies CR confinement and escape in four representative environments: a Milky Way-like galaxy, a starburst galaxy, a galaxy cluster, and a cosmological filament. By solving the transport of a confined CR proton population in each structure using a diffusion/streaming propagation approach with hadronic pp and p

γ

interactions, and treating neutron production and decay as a stochastic Poisson “jump” process, we find that neutron-mediated steps can allow additional CR escape from large-scale cosmological structures at energies where charged-particle transport alone would predict strong CR confinement and attenuation in ambient radiation fields. These effects imply a qualitative shift in how ultra-high-energy CRs are transferred from embedded sources into filaments and voids once intermediate neutron propagation is considered, with consequences for the partitioning of CRs across the large-scale structure of the Universe. Full article

(This article belongs to the Special Issue Studying Astrophysics with High-Energy Cosmic Particles)

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21 pages, 26584 KB

Open AccessArticle

Connecting Meteorite Spectra to Lunar Surface Composition Using Hyperspectral Imaging and Machine Learning

by Fatemeh Fazel Hesar, Mojtaba Raouf, Amirmohammad Chegeni, Peyman Soltani, Bernard Foing, Elias Chatzitheodoridis, Michiel J. A. de Dood and Fons J. Verbeek

Universe 2026, 12(4), 93; https://doi.org/10.3390/universe12040093 - 24 Mar 2026

Viewed by 852

Abstract

We present an innovative, cost-effective framework integrating laboratory Hyperspectral Imaging (HSI) of the Bechar 010 Lunar meteorite with ground-based lunar HSI and supervised Machine Learning (ML) to generate high-fidelity mineralogical maps. A 3 mm thin section of Bechar 010 was imaged under a [...] Read more.

We present an innovative, cost-effective framework integrating laboratory Hyperspectral Imaging (HSI) of the Bechar 010 Lunar meteorite with ground-based lunar HSI and supervised Machine Learning (ML) to generate high-fidelity mineralogical maps. A 3 mm thin section of Bechar 010 was imaged under a microscope with a 30 mm focal length lens at 150 mm working distance, using 6x binning to increase the signal-to-noise ratio, producing a data cube (X × Y ×

λ

=

791 \times 1024 \times 224

,

0.24

mm ×

0.2

mm resolution) across 400 nm to 1000 nm (224 bands,

2.7

nm spectral sampling,

5.5

nm full width at half maximum spectral resolution) using a Specim FX10 camera. Ground-based lunar HSI was captured with a Celestron 8SE telescope (3 km/pixel), yielded a data cube (

371 \times 1024 \times 224

). Solar calibration was performed using a Spectralon reference (99% reflectance < 2% error) ensured accurate reflectance spectra. A Support Vector Machine (SVM) with a radial basis function kernel, trained on expert-labeled spectra, achieved 93.7% classification accuracy (5-fold cross-validation) for olivine (92% precision, 90% recall) and pyroxene (88% precision, 86% recall) in Bechar 010. LIME analysis identified key wavelengths (e.g., 485 nm, 22.4% for M3; 715 nm, 20.6% for M6) across 10 pre-selected regions (M1 to M10), indicating olivine-rich (Highland-like) and pyroxene-rich (Mare-like) compositions. SAM analysis revealed angles from

0.26

rad to

0.66

rad, linking M3 and M9 to Highlands and M6 and M10 to Mares. K-means clustering of Lunar data identified 10 mineralogical clusters (88% accuracy), validated against Chandrayaan-1 Moon mineralogy Mapper (

M^{3}

) data (140 m/pixel, 10 nm spectral resolution). A novel push-broom HSI approach with a telescope achieves 0.8 arcsec resolution for lunar spectroscopy, inspiring full-sky multi-object spectral mapping. Full article

(This article belongs to the Section Planetary Sciences)

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13 pages, 265 KB

Open AccessArticle

The Lemaître–Tolman–Bondi Metric with a Central Pointlike Mass

by Stefan B. Rüster and Antonino Del Popolo

Universe 2026, 12(4), 92; https://doi.org/10.3390/universe12040092 - 24 Mar 2026

Viewed by 1367

Abstract

We present a comprehensive general relativistic analysis of the Lemaître–Tolman–Bondi (LTB) metric, incorporating a cosmological constant

Λ

and a central pointlike mass

M_{d}

at the geometric origin. Within this framework,

M_{d}

is identified as the material source of dark matter in [...] Read more.

We present a comprehensive general relativistic analysis of the Lemaître–Tolman–Bondi (LTB) metric, incorporating a cosmological constant

Λ

and a central pointlike mass

M_{d}

at the geometric origin. Within this framework,

M_{d}

is identified as the material source of dark matter in cosmology, yielding a scale-dependent total matter–density parameter

Ω_{m} (L)

characterized by an

L^{- 3}

decay of its dark component

Ω_{d} (L)

. We demonstrate that the Hubble and

S_{8}

tensions are not independent anomalies but interconnected consequences of spacetime inhomogeneity. These discrepancies arise from a combination of physical and methodological factors: the probing of radial gradients at different characteristic scales and the subsequent interpretation of these data through a global FLRW template. This approach, compounded by the practice of isotropic sky averaging, masks the underlying LTB geometry and converts the physical variation of the manifold into the observed cosmological tensions. Our framework provides a self-consistent geometric explanation for current anomalies while preserving the Copernican principle, identifying the crisis in cosmology as arising from the application of homogeneous models to a manifold characterized by radial gradients and scale-dependent dynamics, where the observer and probes reside within the same inhomogeneous regime. Full article

(This article belongs to the Section Cosmology)

25 pages, 1711 KB

Open AccessReview

The Spherical Nucleus Puzzle and the Discovery of the New Spherical-like γ-Soft Spectra

by Tao Wang

Universe 2026, 12(4), 91; https://doi.org/10.3390/universe12040091 - 24 Mar 2026

Viewed by 920

Abstract

Since the 1950s, nuclear physicists have believed that we have a complete conceptual framework for understanding the low(est)-energy excitations of atomic nuclei. This perspective has persisted in contemporary nuclear structure research, but it now appears overly optimistic. In this review, I present two [...] Read more.

Since the 1950s, nuclear physicists have believed that we have a complete conceptual framework for understanding the low(est)-energy excitations of atomic nuclei. This perspective has persisted in contemporary nuclear structure research, but it now appears overly optimistic. In this review, I present two previously unexpected discoveries, one experimental and one theoretical. Although the spherical phonon excitation spectrum has been considered a typical paradigm of collective excitations in nuclear structure theories, it has not been supported by recent experiments. The result of this experimental discovery reveals a new

γ

-soft rotational mode which has never been predicted by previous theories. This mode differs from previous

γ

-soft ones and can be described by the newly proposed SU3-IBM theory, a new spherical-like

γ

-soft mode representing a specific shape phase. Full article

(This article belongs to the Special Issue 10th Anniversary of Universe: Studying the Strongly Interacting Matter in Nuclear Reactions from Intermediate to Ultra-Relativistic Energies)

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