arXiv subjects

Herman J. Mosquera Cuesta

Publications and source records attributed to Herman J. Mosquera Cuesta.

At least 19 recordsLinked to original sources

arXiv2026

Testing the QGP Star Hypothesis: The oMEGACat BH-2 System as a Candidate Color-Superconducting Quark-Gluon Plasma Star

The recent discovery of a long-period binary system in the globular cluster $ω$ Centauri, oMEGACat BH-2 \citep{Whitaker2026}, provides an unprecedented opportunity to probe the true nature of compact dark objects. The system's massive, dark companion has been inferred to have a mass of $4.46_{-1.01}^{+1.22} M_\odot$, which places it in the ``mass gap'' between neutron stars and the canonical stellar-mass black holes. In this Letter, we explore the hypothesis that the oMEGACat BH-2 companion is not a classical black hole, but a stable, self-bound Quark-Gluon Plasma (QGP) star, as described by recent general relativistic models that incorporate Nonlinear Electrodynamics (NLED) and the asymptotic freedom of Quantum Chromodynamics (QCD) \citep{Mosquera2025}. We compare the inferred mass of the companion with the novel Mass-Radius ($M$-$R$) relation predicted by the QGP star model. We find that the inferred mass of the $ω$ Centauri object lies squarely within the wide mass spectrum predicted for hypermassive QGP stars ($0$ to $>7$ $M_\odot$). Although this consistency is not enough for claiming evidence, it suggests that oMEGACat BH-2 may be the first observed candidate for a QGP star, representing a stable, non-singular end-state of stellar collapse. We argue that future astrometric monitoring with JWST and radio-telescopes like FAST and SKA can further constrain the oMEGACat BH-2 orbital parameters. Meanwhile, gravitational-wave follow-ups for the $f$ and $g$ modes by observatories like LIGO, VIRGO, KAGRA, LISA, ET and CE can be crucial for distinguishing a classical black hole from the ``gravitational eternally collapsing `kompact' object'' (\GECKO) state of our QGP star model.

astro-ph.HE↗

arXiv2026

Asymptotic Freedom and Vacuum Polarization Determine the Astrophysical End State of Relativistic Gravitational Collapse: Quark--Gluon Plasma Star Instead of Black Hole

A general relativistic model of an astrophysical hypermassive extremely magnetized ultra-compact self-bound quark--gluon plasma object that is supported against its ultimate gravitational implosion by the simultaneous action of the vacuum polarization driven by nonlinear electrodynamics (NLED: light-by-light scattering) and the quantum chromodynamics (QCD) asymptotic freedom, is presented. These QCD stars can be the final figures of the equilibrium of collapsing stellar cores. Post-supernova fallback material pushes the nascent remnant beyond its stability to collapse into a hybrid hypermassive neutron star (HHMNS). Hypercritical accretion can unbind the whole HHMNS's baryons to spontaneously break away color confinement, powering a first-order hadron-to-quark phase transition to a sea of ever-freer quarks and gluons. This core is hydro-stabilized by the steady, endlessly compression-admitting asymptotic freedom state, possibly via gluon-mediated enduring exchange of color charge among bound states. The nonlinear TOV equation indicates the occurrence of hypermassive QGP/QCD stars with a wide mass spectrum ($0\lesssim$ M$^{\rm{QGP}}_{\rm{Star}}\lesssim$\,7\,M$_\odot$ and beyond), for star radii ($0\lesssim R^{\rm{QGP}}_{\rm{Star}}\lesssim 24$\,km and beyond) with B-fields ($10^{14} \leq$ B$^{\rm{QGP}}_{\rm{Star}} \leq 10^{16}$\,G and beyond). Such QCD stars can emulate what the true black holes are supposed to gravitationally do in most astrophysical settings. This color quark star could be found through a search for its eternal ``yo-yo'' state gravitational-wave emission, or via lensing phenomena like gravitational rainbows, as in this scenario it is expected that the light deflection angle, directly influenced by the larger effective mass/radius and magnetic field of the deflecting object, increases as the incidence angle decreases for impact parameter lower values.

gr-qc↗

arXiv2017

Probing nonlinear electrodynamics in slowly rotating spacetimes through neutrino astrophysics

Huge electromagnetic fields are known to be present during the late stages of the dynamics of supernovae. Thus, when dealing with electrodynamics in this context, the possibility may arise to probe nonlinear theories (generalizations of the Maxwellian electromagnetism). We firstly solve Einstein field equations minimally coupled to an arbitrary (current-free) nonlinear Lagrangian of electrodynamics (NLED) in the slow rotation regime $a\ll M$ (black hole's mass), up to first order in $a/M$. We then make use of the robust and self-contained Born-Infeld Lagrangian in order to compare and contrast the physical properties of such NLED spacetime with its Maxwellian counterpart (a slowly rotating Kerr-Newman spacetime), especially focusing on the astrophysics of both neutrino flavor oscillations ($ν_e \rightarrow ν_μ, ν_τ$) and spin-flip ($ν_l \rightarrow ν_r$, "$l$" stands for "left" and "$r$" stands for "right", change of neutrino handedness) mass level-crossings, the equivalent to gyroscopic precessions. Such analysis proves that in the spacetime of a slowly rotating nonlinear charged black hole (RNCBH), intrinsically associated with the assumption the electromagnetism is nonlinear, the neutrino dynamics in core-collapse supernovae could be significantly changed. In such astrophysical environment a positive enhancement (reduction of the electron fraction $Y_e<0.5$) of the r-process may take place. Consequently, it might result in hyperluminous supernova explosions due to enlargement, in atomic number and amount, of the decaying nuclides. Finally, we envisage some physical scenarios that may lead to short-lived charged black holes with high charge-to-mass ratios (associated with unstable highly magnetized neutron stars) and ways to possibly disentangle theories of the electromagnetism from other black holes observables (by means of light polarization measurements).

gr-qc↗

arXiv2011

High-energy scalarons in R^{2} gravity as a model for Dark Matter in galaxies

We show that in the framework of R^{2} gravity and in the linearized approach it is possible to obtain spherically symmetric stationary states that can be used as a model for galaxies. The model can also help to have a better understanding on the theoretical basis of Einstein-Vlasov systems. Specifically, we discuss, in the linearized R^{2} gravity, the solutions of a Klein-Gordon equation for the spacetime curvature. Such solutions describe high energy scalarons, a field that in the context of galactic dynamics can be interpreted like the no-light-emitting galactic component. That is, these particles can be figured out like wave-packets showing stationary solutions in the Einstein-Vlasov system. As pertinent to the issue under analysis in this paper, we present an analysis on the gravitational lensing phenomena within this framework. Although the main goal of this paper is to give a potential solution to the Dark Matter Problem within galaxies, we add a Section where we show that an important property of the Bullet Cluster can in principle be explained in the scenario introduced in this work. To the end, we discuss the generic prospective to give rise to the Dark Matter component of most galaxies within extended gravity.

gr-qc↗

arXiv2011

Irreversible gravitational collapse: black stars or black holes?

It is well known that the concept of black hole has been considered very fascinating by scientists even before the introduction of Einstein's general relativity. They should be the final result of an irreversible gravitational collapse of very massive bodies. However, an unsolved problem concerning such objects is the presence of a space-time singularity in their core. Such a problem was present starting by the first historical papers concerning black holes. It is a common opinion that this problem could be solved when a correct quantum gravity theory will be, finally, constructed. In this work we review a way to remove black hole singularities at a classical level i.e. without arguments of quantum gravity. By using a particular non-linear electrodynamics Lagrangian, an exact solution of Einstein field equations is shown. The solution prevents the collapsing object to reach the gravitational radius, thus the final result becomes a black star, i.e. an astrophysical object where both of singularities and event horizons are removed. Such solution is not only a mathematical artifice. In fact, this kind of Lagrangian has been recently used in various analysis in astrophysics, like surface of neutron stars and pulsars. The authors also recently adapted the analysis on a cosmological context by showing that the big-bang singularity can be removed too.

gr-qc↗

arXiv2011

Nonlinear Electrodynamics: Alternative Field Theory for Featuring Photon Propagation Over Weak Background Electromagnetic Fields and what Earth Receivers Read off Radio Signals from Interplanetary Spacecraft Transponders

A few observational and/or experimental results have dramatically pushed forward the research program on gravity as those from the radio-metric Doppler tracking received from the Pioneer 10 and 11 spacecrafts when the space vehicles were at heliocentric distances between 20 and 70 Astronomical Units (AU). These data have conclusively demonstrated the presence of an anomalous, tiny and blue-shifted frequency drift that changes smoothly at a rate of $ \sim 6 \times 10^{-9}$ Hz s$^{-1}$. Those signals, if interpreted as a gravitational pull of the Sun on each Pioneer vehicle, translates into a deceleration of $a_P = (8.74\pm 1.33) \times 10^{-10}$ m s$^{-2}$. This Sunward acceleration appears to be a violation of Newton's inverse-square law of gravitation, and is referred to as the Pioneer anomaly, the nature of which remains still elusive to unveil. Within the theoretical framework of nonlinear electrodynamics (NLED) in what follows we will address this astrodynamics puzzle, which over the last fifteen years has challenged in a fundamental basis our understanding of gravitational physics. To this goal we will first, and briefly, review the history of the Pioneers 10 and 11 missions. Then a synopsis of currently available Lagrangian formulations of NLED is given. And finally, we present our solution of this enigma by invoking a special class of NLED theories featuring a proper description of electromagnetic phenomena taking place in environments where the strength of the (electro)magnetic fields in the background is decidedly low.

physics.gen-ph↗

arXiv2011

Removing black-hole singularities with nonlinear electrodynamics

We propose a way to remove black hole singularities by using a particular nonlinear electrodynamics Lagrangian that has been recently used in various astrophysics and cosmological frameworks. In particular, we adapt the cosmological analysis discussed in a previous work to the black hole physics. Such analysis will be improved by applying the Oppenheimer-Volkoff equation to the black hole case. At the end, fixed the radius of the star, the final density depends only on the introduced quintessential density term $ρ_γ$ and on the mass.

gr-qc↗

arXiv2010

Inflation from R^2 gravity: a new approach using nonlinear electrodynamics

We discuss another approach regarding the inflation from the R^2 theory of gravity originally proposed by Starobinski. A non-singular early cosmology is proposed, where, adding a nonlinear electrodynamics Lagrangian to the high-order action, a bouncing is present and a power-law inflation is obtained. In the model the Ricci scalar works like an inflaton field.

physics.gen-ph↗

arXiv2009

Primordial magnetic fields and gravitational baryogenesis in nonlinear electrodynamics

The amplification of the primordial magnetic fields and the gravitational baryogenesis, a mechanism that allows to generate the baryon asymmetry in the Universe by means of the coupling between the Ricci scalar curvature and the baryon current, are reviewed in the framework of the nonlinear electrodynamics. To study the amplification of the primordial magnetic field strength, we write down the gauge invariant wave equations and then solve them (in the long wavelength approximation) for three different eras of the Universe: de Sitter, the reheating and the radiation dominated era. Constraints on parameters entering the nonlinear electrodynamics are obtained by using the amplitude of the observed galactic magnetic fields and the baryon asymmetry, which are characterized by the dimensionless parameters $r\sim 10^{-37}$ and $η_B\lesssim 9\times 10^{-11}$, respectively.

astro-ph.CO↗

arXiv2009

A spherically symmetric and stationary universe from a weak modification of general relativity

It is shown that a weak modification of general relativity, in the linearized approach, renders a spherically symmetric and stationary model of the universe. This is due to the presence of a third mode of polarization in the linearized gravity in which a "curvature" energy term is present. Such an energy can, in principle, be identified as the Dark Energy. The model can also help to a better understanding of the framework of the Einstein-Vlasov system.

gr-qc↗

arXiv2008

The gravitational wave signal of the short rise fling of galactic run away pulsars

Determination of pulsar parallaxes and proper motions addresses fundamental astrophysical open issues. Here, the ATNF Catalog is scrutinized searching for pulsar distances and proper motions. For a sample of 212 run away pulsars (RAPs), which currently run across the Galaxy at very high speed and undergo large displacements, some gravitational-wave (GW) signals produced by such present accelerations appear to be detectable after calibration against the Advanced LIGO (LIGO II). Motivated by this insight, we address the issue of the pulsar kick at birth. We show that during the short rise fling each run away pulsar (RAP) generates a GW signal with characteristic amplitude and frequency that makes it detectable by current GW interferometers. For a realistic analysis, an efficiency parameter is introduced to quantify the expenditure of the rise fling kinetic energy, which is estimated from the linear momentum conservation law applied to the supernova explosion that kicks out the pulsar. The remaining energy is supposed to be used to make the star to spin. Thus, a comparison with the spin of ATNF pulsars having velocity in the interval 400-500 km s$^{-1}$ is performed. The resulting difference suggests that other mechanisms should dissipate part of that energy to produce the observed pulsar spin periods. Meanwhile, the kick phenomenon may also occur in globular and open star clusters at the formation or disruption of very short period compact binary systems wherein abrupt velocity and acceleration similar to those given to RAPs during the short rise fling can be imparted to each orbital partner. Thus pulsar astrometry from micro- to nano-arsec scales might be of much help. In case of a supernova, the RAP GW signal could be a benchmark for the GW signal from the core collapse.

astro-ph↗

arXiv2008

Neutrino mass spectrum from gravitational waves generated by double neutrino spin-flip in supernovae

The supernova (SN) neutronization phase produces mainly electron ($ν_e$) neutrinos, the oscillations of which must take place within a few mean-free-paths of their resonance surface located nearby their neutrinosphere. The state-of-the-art on the SN dynamics suggests that a significant part of these $ν_e$ can convert into right-handed neutrinos in virtue of the interaction of the electrons and the protons flowing with the SN outgoing plasma, whenever the Dirac neutrino magnetic moment be of strength $μ_ν< 10^{-11} μ_{\rm B}$, with $μ_{\rm B}$ being the Bohr magneton. In the supernova envelope, part of these neutrinos can flip back to the left-handed flavors due to the interaction of the neutrino magnetic moment with the magnetic field in the SN expanding plasma (Kuznetsov & Mikheev 2007; Kuznetsov, Mikheev & Okrugin 2008), a region where the field strength is currently accepted to be $B \gtrsim 10^{13}$ ~G. This type of $ν$ oscillations were shown to generate powerful gravitational wave (GW) bursts (Mosquera Cuesta 2000, Mosquera Cuesta 2002, Mosquera Cuesta & Fiuza 2004, Loveridge 2004). If such double spin-flip mechanism does run into action inside the SN core, then the release of both the oscillation-produced $ν_μ$s, $ν_τ$s and the GW pulse generated by the coherent $ν$ spin-flips provides a unique emission offset $ΔT^{emission}_{\rm GW} \leftrightarrow ν= 0$ for measuring the $ν$ travel time to Earth. As massive $ν$s get noticeably delayed on its journey to Earth with respect to the Einstein GW they generated during the reconversion transient, then the accurate measurement of this time-of-flight delay by SNEWS + LIGO, VIRGO, BBO, DECIGO, etc., might readily assess the absolute $ν$ mass spectrum.

astro-ph↗

arXiv2008

Nonlinear electrodynamics and the variation of the fine structure constant

It has been claimed that during the late time history of our universe, the fine structure constant of electromagnetism, $α$, has been increasing (Webb et al. 2001; Murphy et al. 2003). The conclusion is achieved after looking at the separation between lines of ions like CIV, MgII, SiII, FeII, among others in the absorption spectra of very distant quasars, and comparing them with their counterparts obtained in the laboratory. However, in the meantime, other teams has claimed either a null result or a decreasing $α$ with respect to the cosmic time (Chand et al. 2004; Levshakov et al. 2004). Also, the current precision of laboratory tests does not allow one to either comfort or reject any of these astronomical observations. Here we suggest that as photons are the sidereal messengers, a nonlinear electrodynamics (NLED) description of the interaction of photons with the weak local background magnetic fields of a gas cloud absorber around the emitting quasar can reconcile the Chand et al. (2004) and Levshakov et al. (2004) findings with the negative variation found by Murphy et al. (2001a, 2001b, 2001c, 2001d) and Webb et al. (2001), and also to find a bridge with the positive variation argued more recently by Levshakov et al. (2006a, 2007). We also show that nonlinear electrodynamics photon propagation in a vacuum permeated by a background magnetic field presents a full agreement with constraints from Oklo natural reactor data. Finally, we show that NLED may render a null result only in a narrow range of the local background magnetic field which should be the case of both the claims by Chand et al.(2004) and by Srianand et al. (2004).

astro-ph↗

arXiv2007

Cosmological redshift and nonlinear electrodynamics propagation of photons from distant sources

By-now photons are the unique universal messengers. Cosmological sources like far-away galaxies or quasars are well-known light-emitters. Here we demonstrate that the nonlinear electrodynamics (NLED) description of photon propagation through the weak background intergalactic magnetic fields modifies in a fundamental way the cosmological redshift that a direct computation within a specific cosmological model can abscribe to a distant source. Independently of the class of NLED Lagrangian, the effective redshift turns out to be $1 + \tilde{z} = (1 + z) Δ$, where $Δ\equiv (1 + Φ_e)/(1 + Φ_o)$, with $Φ\equiv {8}/{3} ({L_{FF}}/{L_F}) B^2$, being $L_F = {dL}/{dF}$, $L_{FF} = {d^2L}/{dF^2}$, the field $F\equiv F_{αβ} F^{αβ}$, and $B$ the magnetic field strength. Thus the effective redshift is always much higher then the standard redshift, but recovers such limit when the NLED correction $Δ(Φ_e, Φ_o) \longrightarrow 1$. This result may provide a physical foundation for the current observation-inspired interpretation that the universe undergoes an accelerate expansion. However, under the situation analyzed here, for any NLED the actual (spatial) position of the light-emitting far-away source remains untouched.

astro-ph↗

arXiv2007

Confronting the Hubble Diagram of Gamma-Ray Bursts with Cardassian Cosmology

We construct the Hubble diagram (HD) of Gamma-Ray Bursts (GRBs) with redshifts reaching up to $z \sim 6$, by using five luminosity vs. luminosity indicator relations calibrated with the Cardassian cosmology. This model has a major interesting feature: despite of being matter-dominated and flat, it can explain the present accelerate expansion of the universe. This is the first study of this class of models using high redshift GRBs. We have performed a $χ$-square statistical analysis of the GRBs calibrated with the Cardassian model, and also combined them with both the current Cosmic Microwave Background and Baryonic Acoustic Oscillation data. Our results show consistency between the current observational data and the model predictions. In particular, the best-fit parameters obtained from the $χ^2$-analysis are in agreement with those obtained from the Concordance Cosmology ($Λ$-CDM). We determine the redshift at which the universe would start to follow the Cardassian expansion, i. e., \zc, and both the redshift at which the universe had started to accelerate, i. e., \zac, and the age-redshift relation $H_0t_0$. Our results also show that the universe, from the point of view of GRBs, had undergo a transition to acceleration at a redshift $z \approx 0.2-0.7$, which agrees with the SNIa results. Hence, after confronting the Cardassian scenario with the GRBs HD and proving its consistency with it, we conclude that GRBs should indeed be considered a complementary tool to several other astronomical observations for studies of high accuracy in cosmology.

astro-ph↗

arXiv2007

Is the Bardeen-Petterson effect responsible for the warping and precession in NGC 4258?

Strong evidence for the presence of a warped Keplerian accretion disc in NGC4258 (M 106) has been inferred from the kinematics of water masers detected at sub-parsec scales. Assuming a power-law accretion disc and using constraints on the disc parameters derived from observational data, we have analyzed the relativistic Bardeen-Petterson effect driven by a Kerr black hole as the potential physical mechanism responsible for the disc warping. We found that the Bardeen-Petterson radius is comparable to or smaller than the inner radius of the maser disc (independent of the allowed value for the black hole spin parameter). Numerical simulations for a wide range of physical conditions have shown that the evolution of a misaligned disc due to the Bardeen-Petterson torques usually produces an inner flat disc and a warped transition region with a smooth gradient in the tilt and twist angles. Since this structure is similar to that seen in NGC 4258, we propose that the Bardeen-Petterson effect may be responsible for the disc warping in this galaxy. We estimated the time-scale necessary for the disc inside of the Bardeen-Petterson radius to align with the black hole's equator, as a function of the black hole spin. Our results show that the Bardeen-Petterson effect can align the disc within a few billion years in the case of NGC 4258. Finally, we show that if the observed curvature of the outer anomalous arms in the galactic disc of NGC 4258 is associated with the precession of its radio jet/counterjet, then the Bardeen-Petterson effect can provide the required precession period.

astro-ph↗

arXiv2006

Nonlinear electrodynamics and the Pioneer 10/11 spacecraft anomaly

The occurrence of the phenomenon known as photon acceleration is a natural prediction of nonlinear electrodynamics (NLED). This would appear as an anomalous frequency shift in any modeling of the electromagnetic field that only takes into account the classical Maxwell theory. Thus, it is tempting to address the unresolved anomalous, steady; but time-dependent, blueshift of the Pioneer 10/11 spacecrafts within the framework of NLED. Here we show that astrophysical data on the strength of the magnetic field in both the Galaxy and the local (super)cluster of galaxies support the view on the major Pioneer anomaly as a consequence of the phenomenon of photon acceleration. If confirmed, through further observations or lab experiments, the reality of this phenomenon should prompt to take it into account in any forthcoming research on both cosmological evolution and origin and dynamical effects of primordial magnetic fields, whose seeds are estimated to be very weak.

astro-ph↗

arXiv2006

Hubble diagram of gamma-ray bursts: Robust evidence for a Chaplygin gas expansion-driven universe with phase transition at $z \simeq 3$

The Hubble diagram (HD) of Gamma-Ray Bursts (GRBs) having properly estimated redshifts is compared with the predicted one for the Chaplygin gas (CG), a dark energy candidate. The CG cosmology and that of Friedmann and $Λ$-CDM models are studied and confronted to the GRBs observations. The model-to-sample $χ^2$ statistical analysis indicates the CG model as the best fit. The present GRBs HD plot exhibits a marked trend: as one goes back in time, it gets much closer to the predict HD for a Friedmann universe. This clear trend conclusively demonstrates that a transition from decelerate to accelerate expansion did take place. However, contrarily to claims based on supernovae type Ia, the transition redshift lies somewhere between $\sim 2.5 < z \simeq 3.5$ rather than at $z \sim 0.5-1$. All of these striking features of the GRBs HD constitute the most robust demonstration that the Chaplygin gas can in fact be the universe's driving dark energy field.

astro-ph↗