arXiv subjects

Débora P. Menezes

Publications and source records attributed to Débora P. Menezes.

At least 19 recordsLinked to original sources

arXiv2026

A self-consistent single-fluid framework for neutron stars admixed with mirror dark matter

We develop a self-consistent dark matter admix neutron star framework based on a contact vector current--current interaction that couples the chemical potentials of both sectors through mutual mean-field shifts, with the dark matter (DM) fraction $F_D = N_D/N_B$ fixed as a global input parameter. This formulation provides a physically motivated alternative to fixed-density prescriptions, allowing the local DM density to follow the baryonic matter (BM) density throughout the stellar interior. As an application, we consider a mirror-DM scenario with exact symmetry between the dark and visible sectors and investigate NS matter using the NL3$ωρ$, FSU2R, NL3, and DDME2 equations of state (EOSs). We find that the amount of DM introduced through $F_D$ weakens the binding of dense matter, reduces its incompressibility, and softens the EOS, while the DM--BM interaction governs the microscopic behavior of the DM in the dense BM medium. Consequently, DM increases the central density and compactness of NSs, lowers their maximum masses, and shifts the onset of the direct Urca process to higher stellar densities. As a consequence, the onset of rapid cooling is shifted to more massive stars for models with a stiff symmetry energy and to less massive stars for models with a soft symmetry energy, depending on the extra compactness that results from the DM admixture. These results demonstrate that mirror-DM admixtures modify both the microscopic composition and macroscopic structure of NSs, with potential implications for their thermal evolution and multimessenger observational signatures.

astro-ph.HE↗

arXiv2026

Effects of the symmetry energy slope on magnetized neutron stars

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 in neutron stars' universal relations.

astro-ph.HE↗

arXiv2026

Dark Matter Heating in Evolving Proto-Neutron Stars: A Two-Fluid Approach

Neutron stars (NSs) provide a unique laboratory to probe dark matter (DM) through its gravitational imprint on stellar evolution. We use a two-fluid framework with non-annihilating, asymmetric DM, both fermionic and bosonic, that interacts with ordinary matter (OM) solely through gravity. Within this framework, we track protoneutron stars (PNSs) across their thermal and compositional evolution via quasi-static modeling over the Kelvin--Helmholtz cooling timescale. We uncover a distinct thermal signature: DM cores deepen the gravitational potential, compressing and heating the baryonic matter, while extended DM halos provide external support, leading to cooling of the stellar matter. In contrast, hyperons and other exotic baryons soften the equation of state similarly to DM cores but reduce, rather than increase, the temperature. DM thus alters both temperature and particle distribution profiles in ways that provide a clear diagnostic of its presence. DM cores also enhance compactness and shift hyperon onset, with the strongest effects during deleptonization and neutrino-transparent phases due to reduced neutrino pressure contributions. Consequently, this early thermal evolution, observable through supernova neutrino light curves and young pulsar cooling curves, offers a direct, testable probe of DM in NSs.

astro-ph.HE↗

arXiv2025

Proto-neutron Stars with Dark Matter Admixture: A Single-Fluid Approach

This work investigates the impact of dark matter (DM) on the microscopic and macroscopic properties of proto-neutron stars (PNSs). We employ a single-fluid framework in which DM interacts with ordinary matter (OM) via the Higgs portal and remains in thermal equilibrium through non-gravitational interactions. Using a quasi-static approximation, we analyze the evolution of PNSs during the Kelvin-Helmholtz phase by varying the DM mass while keeping the entropy per baryon and lepton fraction fixed. Our results show that DM absorbs thermal energy from the stellar medium without efficient re-emission, thereby altering neutrino emission and affecting the star's thermal evolution history. Furthermore, neutrinos contribute significantly to pressure support in the PNS phase, inhibiting DM mass accretion during neutrino-trapped stages. Based on the requirement to satisfy the observed $2,\rm M_\odot$ neutron star mass constraint and to maintain consistency with supernova remnant data, we suggest an upper limit of $m_χ\leq 0.62,\rm GeV$ for the DM mass that can accrete in evolving PNSs, within the model framework. In contrast, we established that cold neutron stars (NSs) can support higher DM masses without compromising equilibrium stability, owing to increased central density, enhanced gravitational binding energy, and reduced thermal pressure.

astro-ph.HE↗

arXiv2025

Hyperons and $Δ$'s in rotating protoneutron stars: Local properties

The structural evolution of rotating protoneutron stars encodes essential information about their observable signatures, while microscopic properties provide complementary knowledge to advance observational investigations. Using a relativistic mean-field model with density-dependent couplings that account for temperature and particle composition, we investigate rotation, neutrino-emission-driven changes in angular momentum, particle distributions, temperature profiles, and sound speed to probe the internal dynamics of protoneutron star matter. Additionally, we track the evolution of macroscopic quantities such as energy distribution and gravitational mass and establish direct links between microphysics and global evolution. Extending the framework of Phys. Rev. D 112, 023007 (2025), which focuses on the global properties of rotating protoneutron star evolution, our results reveal that protoneutron star deformation and thermal evolution are governed by angular momentum, mass, and composition. Exotic matter (hyperons and $Δ$-resonances) and rapid rotation enhance deformation leading to a reduction in core temperature, whereas slowly rotating stars like PSR J0740$+$6620 remain nearly spherical. Our predicted equatorial radii for PSR J0740$+$6620, $13.0\ \mathrm{km} < R_e < 13.5\ \mathrm{km}$, are consistent with NICER measurements. These findings constrain the EoS, requiring a self-consistent treatment of rotation, mass-dependent compression, and composition-driven modeling to accurately model protoneutron star evolution in the context of multi-messenger astrophysics.

astro-ph.HE↗

arXiv2025

Hyperons and $Δ$'s in rotating protoneutron stars: Global properties

Rotation plays an important role in the evolution of most types of stars, in particular, it can have a strong influence on the evolution of a newly born proto-neutron star. In this study, we investigate the effects of rotation on four snapshots of the evolution of proto-neutron stars with hyperons and $Δ$-resonances in their cores, from birth as neutrino-rich objects to maturity as cold, catalyzed neutron stars. We focus on the effects of uniform rotation on the macroscopic structure of the star at three rotational frequencies -- 346.53 Hz, 716 Hz, and the Kepler frequency. Our investigation indicates that the impact of rotation at frequencies of $346.53$~Hz and $716$~Hz causes minor changes in the maximum gravitational mass but leads to significant changes in the stellar radius, particularly for stars with masses smaller than $2$~\msun. However, we observe drastic changes in the star's mass and radius when considering the Kepler frequency. In addition, we investigate other relevant characteristics of the rotating proto-neutron stars as they evolve such as the moment of inertia, compactness, central temperature, and Kerr parameter. Our results suggest that the inclusion of new degrees of freedom in the stellar core lead the star to be more sensitive to rotational dynamics, owing to an increase in compactness, a decrease in the central temperature, and a decrease in the moment of inertia.

hep-ph↗

arXiv2025

Bayesian Analysis of Non-extensive Parameters in Au-Au Collisions

In this work, a Bayesian statistical framework is employed to analyze particle yield ratios in Au-Au collisions, utilizing Non-Extensive Statistics (NES). Through Markov Chain Monte Carlo (MCMC) sampling, we systematically estimate key parameters, including the non-extensive factor $q$, temperature $T$, and chemical potential $μ$. Our analysis confirms previous findings highlighting the suitability and robustness of Bayesian methods in describing heavy-ion collision data. A subsequent Bayes factor analysis does not provide definitive evidence favoring an Excluded Volume Hadron Resonance Gas (EV-HRG) model over the simpler NES approach. Overall, these results suggest that combining NES with Bayesian inference can effectively model particle distributions and improve parameter estimation accuracy, demonstrating the potential of this approach for future studies on relativistic nuclear interactions.

hep-ph↗

arXiv2025

Strongly Interacting Quark Matter in Massive Quark Stars

This paper investigates the properties of strongly coupled matter at high baryon densities ($ρ_B$) in quark stars (QSs). The QS model is based on the density-dependent quark mass (DDQM) framework, modified (MDDQM) by enhancing the single-gluon interaction to generate higher repulsive pressure. The model parameters are constrained using Bayesian inference, incorporating observational data from the pulsars HESS J1731$-$347, PSR J0030$+$0451, PSR J0740$+$6620, and PSR J0952$-$0607. Our results show that the MDDQM model produces QSs with higher mass and compactness compared to the DDQM model. Among the four MDDQM parameterizations studied, two yield maximum star masses of 1.86 and 2.10 $\rm M_\odot$ and exhibit near-conformal behavior in the underlying quark matter (QM). The other two parameterizations, yielding QS masses of 2.30 and 2.37 $\rm M_\odot$, correspond to a stronger interaction in the underlying QM. These findings provide important insights into the equation of state of deconfined QM and its implications for the structure and stability of QSs.

nucl-th↗

arXiv2025

Constraining the Generalized Tolman-Oppenheimer-Volkoff (GTOV) equation with Bayesian analysis

In this work, we constrain the values of the parameters of the Generalized Tolman-Oppenheimer-Volkoff (GTOV) equation through Bayesian inference. We use the mass and radius data from the Neutron Star Interior Composition Explorer (NICER) for PSR J0740$+$6620 and PSR J0030$+$0451, as well as the mass, radius, and dimensionless tidal deformability from the gravitational wave (GW) events GW190814 and GW170817. We use two distinct parameterizations of the extended non-linear Walecka model (eNLW) with and without hyperons. The GTOV employed for the study contains additional free parameters with different physical motivations. Two possible scenarios are considered in our analysis: conservative and speculative. In the first case, we take into account the most reliable neutron star (NS) data from NICER and the GW170817 event. In the second case, we consider the possibility that the compact object with a mass of $2.54 M_{\odot}$ in the GW190814 event is an NS. Our findings show significant improvements in the physical quantities analyzed, leading to better agreement with the observational data compared to the results obtained using the TOV equation.

astro-ph.HE↗

arXiv2025

Supernova Remnants with Mirror Dark Matter and Hyperons

For the first time, we use relativistic mean-field (RMF) approximation with density-dependent couplings, adjusted by the DDME2 parameterization, to investigate the effects of dark matter on supernova remnants. We calculate the nuclear equation of state for nuclear and dark matter separately, under the thermodynamic conditions related to the evolution of supernova remnants. A mirrored model is adopted for dark matter, and its effect on remnant matter is studied using a two-fluid scenario. At each stage of the remnant evolution, we assume that dark and ordinary matter have the same entropy and lepton fraction, and a fixed proportion of dark matter mass fraction is added to the stellar matter to observe its effects on some microscopic and macroscopic properties of the star. We observe that dark matter in the remnant core reduces the remnant's maximum mass, radius, and tidal deformability. Moreover, dark matter heats the remnant matter and alters particle distributions, thereby decreasing its isospin asymmetry and increasing the sound speed through the matter.

hep-ph↗

arXiv2024

Proto-neutron stars with quark cores

This work investigates the evolution of proto-neutron stars (PNSs) from birth as neutrino-rich objects to maturity as cold-catalyzed neutrino-poor objects with nucleonic and non-nucleonic degrees of freedom. The focus is on the star's core where the nucleons, hyperons, and the $Δ$-isobars are expected to dissolve into a ``soup" of deconfined quarks, at higher baryon densities, to establish a possible hadron-quark phase transition. We separately calculate the nuclear equations of state (EoS) for the hadronic matter (composed of all the baryon octet and $Δ$-isobars) and the strange quark matter (SQM) under the same thermodynamic conditions characteristic of PNS and proto-strange star (PSS) evolution and construct the hybrid EoS using Maxwell's construction. The study allows us to determine the hadron-quark phase transitions along the evolution lines of the star. We observed a phase transition from hadronic matter to quark matter (QM) phase when the neutrinos have completely escaped from the star's core. The EoSs utilized are constrained to meet the $2\,\rm M_\odot$ threshold in accordance with the observational data.

nucl-th↗

arXiv2024

Occurrence of gravitational collapse in the accreting neutron stars of binary-driven hypernovae

The binary-driven hypernova (BdHN) model proposes long gamma-ray bursts (GRBs) originate in binaries composed of a carbon-oxygen (CO) star and a neutron star (NS) companion. The CO core collapse generates a newborn NS and a supernova that triggers the GRB by accreting onto the NSs, rapidly transferring mass and angular momentum to them. This article aims to determine the conditions under which a black hole (BH) forms from NS collapse induced by the accretion and the impact on the GRB observational properties and taxonomy. We perform three-dimensional, smoothed-particle-hydrodynamics simulations of BdHNe using up-to-date NS nuclear equations of state (EOS), with and without hyperons, and calculate the structure evolution in full general relativity. We assess the binary parameters leading either NS in the binary to the critical mass for gravitational collapse into a BH and its occurrence time, $t_{\rm col}$. We include a non-zero angular momentum of the NSs and find that $t_{\rm col}$ ranges from a few tens of seconds to hours for decreasing NS initial angular momentum values. BdHNe I are the most compact (about five minutes orbital period), promptly form a BH and release $\gtrsim 10^{52}$ erg. They form NS-BH binaries with tens of kyr merger timescale by gravitational-wave emission. BdHNe II and III do not form BHs, release $\sim 10^{50}$-$10^{52}$ erg and $\lesssim 10^{50}$ erg. They form NS-NS binaries with a range of merger timescales larger than for NS-BH binaries. In some compact BdHNe II, either NS can become supramassive, i.e., above the critical mass of a non-rotating NS. Magnetic braking by a $10^{13}$ G field can delay BH formation, leading to BH-BH or NS-BH of tens of kyr merger timescale.

astro-ph.HE↗

arXiv2024

Nambu-Jona-Lasinio description of hadronic matter from a Bayesian approach

A microscopic nuclear matter formalism with explicit chiral symmetry based on the Nambu Jona-Lasinio model is considered to describe nuclear matter. To reproduce nuclear matter properties adequately at the saturation density, four-point and eight-point interactions are introduced. Within a Bayesian inference approach, the parameters of the model are determined by imposing nuclear matter, both experimental and from {\it ab-initio} calculations, and neutron star observational constraints. Nuclear matter properties are well reproduced with an effective mass of 0.75 to 0.8 nucleon mass at the saturation density. At 90% confidence level, the radius of a $1.4 ~\rm M_\odot$ star varies between 11.48 km and 13.20 km, masses as large as $\sim 2.2 ~\rm M_\odot$ are predicted and the radius of a 2 M$_\odot$ star is above 10.5 km. High-density perturbative QCD (pQCD) results exclude equations of state that predict larger maximum masses and radii. The speed of sound increases monotonically with density and reaches values as large as $\sqrt{0.7}c$-$\sqrt{0.8}c$ in the center of massive stars. Several properties such as the polytropic index or the renormalized trace anomaly, that have been proposed to identify the deconfined phase transition, are analyzed. Interestingly, the radius of the obtained posterior that also meets pQCD constraints aligns closely with the mass-radius measurement of the recent PSR J0437-4715, which contrasts with other relativistic mean field model results.

nucl-th↗

arXiv2024

Surface and curvature tensions of relativistic models

In the present paper, we show a simple method to obtain fittings for the surface and curvature tensions. The method uses the nuclear mass of a spherical fully ionized atom and a simple expression for the binding energy such that a least square fit is found when confronted with the Atomic Mass Evaluation (AME) 2020. The fittings are then used to evaluate the pasta phase free energy per particle, which is confronted with the one obtained with a Thomas-Fermi fitting. The results are very encouraging and suggest that this recipe can be safely used whenever the surface and curvature tensions are necessary.

nucl-th↗

arXiv2024

A Bayesian study of quark models in view of recent astrophysical constraints

In this work, we perform a comparative analysis between the density-dependent quark model and the vector MIT bag model using Bayesian analysis. We use the equations of state generated by these two models to describe quark stars. We impose four recent observational astrophysical constraints on both models to determine their model-dependent parameters in an optimized manner assuming that the compact objects observed are composed entirely of self-bound quarks. The restrictions are aimed at producing stars with maximum masses $2 - 2.35$ M$_\odot$ and a mass-radii diagram compatible with the observed pulsars: PSR J0740+6620, PSR J0952-0607, PSR J0030+0451 and the compact object XMMU J173203.3-344518. With this analysis, the parameter dependence of the nuclear equation of state (EoS) of both models is restricted.

nucl-th↗

arXiv2024

Non-extensive statistics in Au-Au collisions

Particle production yields measured in central Au-Au collision at RHIC are obtained with free Fermi and Bose gases and also with a replacement of these statistics by non-extensive statistics. For the latter calculation, a set of different parameters was used with values of the Tsallis parameter $q$ chosen between 1.01 and 1.25, with 1.16 generating the best agreement with experimental data, an indication that non-extensive statistics may be one of the underlying features in heavy ion-collisions.

hep-ph↗

arXiv2024

Proto-strange quark stars from density-dependent quark mass model

In this paper, we investigate the evolution of strange quark stars (SQS) from birth as proto-strange quark stars to maturity as stable SQSs at a zero temperature. We assume that self-bound free quarks form {entirely the compact} star and study its evolution {through a series of snapshots} using a density-dependent quark mass model. We consider $β$-equilibrated stellar matter at two major stages of the star's evolution: neutrino trapped regime and neutrino transparent regime during the deleptonization and cooling processes of the star. We fix the entropy density per baryon and the lepton fraction to investigate the nuclear equation of state (EoS), particle distribution, temperature profile inside the star, sound velocity, polytropic index, and the structure of the star. Our results show that stars with higher neutrino concentrations are slightly more massive than the neutrino-poor ones along the evolution lines of the SQS. We obtain EoSs in agreement with the conformal boundary set through sound velocity, and also the 2 M$_\odot$ mass constraint for NSs was satisfied at all stages of the star's evolution.

nucl-th↗

arXiv2023

Do short range correlations inhibit the appearance of the nuclear pasta?

It is well known that strongly correlated neutron-proton pairs, the short-range correlations (SRC), can modify many of the nuclear properties. In this work we have introduced, for the first time, short range correlations in the calculation of the nuclear pasta phase at zero temperature and checked how they affect its size and internal structure. We have used two different parameterizations of relativistic models in a mean field approximation and the coexistence phase approximation as a first estimation of the effects. We have seen that for very asymmetric neutron-proton-electon matter, the pasta phase shrinks considerably as compared with the results without SRC and all internal structures vanish, except the simple spherically symmetric one, the droplets. Our results indicate a possible disappearance of these complicated structures as the temperature increases.

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