arXiv subjects

Tonatiuh Matos

Publications and source records attributed to Tonatiuh Matos.

At least 37 records · Page 2Linked to original sources

arXiv2026

A Brief Review of Wormhole Cosmic Censorship

Spacetime singularities, in the sense that curvature invariants are infinite at some point or region, are thought to be impossible to observe, and must be hidden within an event horizon. This conjecture is called Cosmic Censorship (CC), and was formulated by Penrose. Here we review another type of CC where spacetime singularities are causally disconnected from the universe, because the throat of a wormhole ``sucks in'' the geodesics and prevents them from making contact with the singularity. In this work, we present a series of exact solutions to the Einstein--Maxwell--Dilaton equations that feature a ring singularity; that is, the curvature invariants are singular in this ring, but the ring is causally disconnected from the universe so that no geodesics can touch it. This extension of CC is called Wormhole Cosmic Censorship.

gr-qc↗

arXiv2026

A natural explanation of the Galactic Magnetic Fields from multistate Scalar Field Dark Matter

In this article, we investigate the possibility that the large-scale magnetic fields observed in galaxies, of the order of microgauss, arise naturally from a complex Scalar Field Dark Matter (SFDM) halo charged under a local $U(1)$ symmetry. Extending our previous work, where multistate SFDM solutions were shown to form ``gravitational atoms'' capable of explaining the anisotropic distribution of satellite galaxies (VPOS), we analyze here the coupled dynamics of the scalar and a gauge field at the perturbative level. By solving the perturbed Klein-Gordon and gauge-field equations, we find the temporal evolution and show that the spatial structure of the induced electromagnetic fields is governed by the same spherical Bessel functions and spherical harmonics that characterize the ground and excited states of the multi-state SFDM halo. Remarkably, the presence of the gauge field does not modify the dark-matter density distribution, which preserves the multi-state configuration previously obtained. Our results demonstrate that a charged multi-state SFDM halo can generate coherent, large-scale magnetic fields whose morphology is determined by the excited modes of the scalar field, providing a unified framework in which both galactic magnetic fields and VPOS-like structures originate from the underlying quantum nature of dark matter.

gr-qc↗

arXiv2025

Conformal Holographic Dark Energy

Recent results from the DESI collaboration suggest a preference for an evolving dark energy (DE) component rather than a cosmological constant, motivating the exploration of alternative models for the background expansion. These data also reveal tension in the inferred matter density parameter -- lower in DESI and higher in Planck -- as well as a neutrino mass posterior that approaches the lower bounds permitted by oscillation experiments. In this work, we propose and test a conformal holographic DE (CHDE) model in which the DE density depends on a power law of the conformal time, characterized by an exponent (n). This formulation introduces a single additional parameter relative to LambdaCDM and reduces to it in the limit n = 0. We confront the CHDE model with BAO, CMB, and supernova datasets, following the same combinations used by DESI, and perform parameter inference under both flat and non-flat cosmologies. Our analyses show that LambdaCDM is not favored as the best-fit model when using CMB data alone or in joint analyses including BAO and SNla, and it is disfavored at the 4.4 sigma level for non-flat model and 4.5 sigma for the flat model. We obtain consistent values of n= -0.28 to -0.32 with uncertainties less than +-0.1 across multiple data combinations. Similar to LambdaCDM, the CHDE model predicts a lower matter density when employing DESI data instead of Planck data. This, in turn, influences the neutrino mass constraints, yielding values close to the minimal allowed range. Despite these dataset-dependent tensions, both the flat and curved CHDE models remain compatible with neutrino mass constraints from terrestrial experiments and yield posterior distributions that peaks at positive values. This behavior avoids the issue encountered in the LambdaCDM model, where the posterior peaks at negative mass values.

astro-ph.CO↗

arXiv2025

Wormholes exact solutions in high dimensions General Relativity

In the present work, we develop and examine a series of exact solutions to Einstein's 5-dimensional field equations in the vacuum, which depend on two constant parameters, $p$ and $q$, which generalize the solutions of Lü and Mei [8] belonging to our class $p=2$. This category of solutions can be split into two sections: when $p$ is odd, it represents a compact object that may have naked singularities. However, the intriguing outcome occurs when $p$ is even, as asymptotically Ricci flat wormholes emerge in this scenario. The Kreschman invariant of these solutions depends on the constant parameter $l = 1 + \frac{3 q^2 - p^2}{4}$. When $l = 0$ and $l \leq -\frac{1}{2}$, the solutions are regular. For the specific cases where $l \leq 0$, or $l > 0$ such that $q < 0$ for $p \geq 2$, $q \leq \frac{1}{3}$ for $p = 2$, and $q \leq \frac{1 + \sqrt{2}}{3}$ for $ p \geq 4$, this class of wormholes adheres to Wormhole Cosmic Censorship, implying that the throat effectively obscures all causal anomalies and singularities. In our analysis, we investigated the embedded geometry, geodesics, singularities, potential event horizons, ergoregions, and the wormhole throat.

gr-qc↗

arXiv2025

Fundamental Klein-Gordon equation from stochastic mechanics in curved spacetime

This work presents an alternative approach to obtain the quantum field equations in curved spacetime, considering that sufficiently small particles follow stochastic trajectories around geodesic. Our proposal is based on a stochastic differential equation in which the noise term experienced by the quantum particles is a consequence of the stochastic background in spacetime. This fact allows the particles to describe erratic movements and locally the universe exhibits characteristics akin to a lake with gentle ripples rather than a flat unyielding surface. Building upon this foundational understanding, we investigate the influence of this background on quantum-scale particles without considering the metric to be stochastic, rather we let test particles move randomly around the geodesic of macroscopic particles. Their behavior aligns with solutions to the Klein-Gordon (KG) equation specific to this curved spacetime. As the KG equation, in its non-relativistic limit within a flat spacetime, reduces to the Schrödinger equation, consequently, we propose a compelling connection: the Schrödinger equation may emerge directly from a spacetime lacking local smoothness.

physics.gen-ph↗

arXiv2025

Unitary evolution and cosmic acceleration in Loop Quantum Cosmology

Loop quantum cosmology was shown to interpolate between de Sitter and FLRW Universe phases through a bounce by including Euclidean and Lorentzian terms of the Hamiltonian constraint with weight one -that corresponding to classical General Relativity. Unitary evolution required self-adjoint extensions of the constraint and a Planckian cosmological constant was obtained. Independent work took a positive weight to get a cosmological constant with the observed value, without considering unitarity. In this work we address the unitary evolution of the model for arbitrary weight. For non positive weight parameter unitary holds but for positive values self-adjoint extensions are required. To encompass observations the extensions here provided are mandatory. These are implemented in a propagator. Finally, we discuss our results and perspectives.

gr-qc↗

arXiv2025

Einstein-Maxwell-Dilaton Wormholes that meet the Energy Conditions

One of the latest predictions of Einstein's theory is the existence of Wormholes (WH). In this work, we present exact solutions of the Einstein-Maxwell-Dilaton equations representing traversable Wormholes. These solutions satisfy the energy conditions and have a ring singularity satisfying the cosmic censorship of WHs, i.e. we show that, as in previous solutions, geodesics cannot touch the singularity. We find that the most optimal input regions for the first class of solutions traversing these wormholes are near the poles and near the equatorial plane for the second class. We also find that the solution associated with the first class is physically feasible, while for the second class it presents the problem of not being asymptotically flat when considering a dilatonic-type scalar field. Finally, we give examples of realistic astrophysical objects that could fulfill these conditions.

gr-qc↗

arXiv2025

A Natural Explanation of the VPOS from Multistate Scalar Field Dark Matter

Observations with the Gaia satellite have confirmed that the satellite galaxies of the Milky Way are not distributed as homogeneously as expected. The same occurs in galaxies such as Andromeda and Centaurus A, where satellites around their host galaxies have been observed to have orbits aligned perpendicular to the galactic plane of the host galaxy. This problem is known for the Milky Way as Vast Polar Structure (VPOS). The Scalar Field Dark Matter Field (SFDM), also known as Ultralight-, Fuzzy-, BEC-, and Axion-dark matter, proposes dark matter is a scalar field, which in the non-relativistic limit follows the Schrödinger equation coupled to the Poisson equation. Although the SF here is classical, the Schrödinger equation contains a ground and excited states as part of its nature. In this work, we show that such quantum character of the SFDM can naturally explain the VPOS observed in galaxies. By taking into account the finite temperature corrections for a complex, self-interacting SF at very early epochs of the Universe, we show that with the ground and first excited states in the Newtonian limit, we can fit the rotation curves of the host galaxies. With the best-fit parameters obtained, we can explain the VPOS. We do this with particular galaxies, such as the Milky Way, Andromeda, Centaurus A, and 6 other galaxies whose satellites have been observed. This result shows that the multistate SFDM is not distributed homogeneously around the galaxy, and therefore might explain the anisotropic distribution of the satellite galaxies. According to this result, this could be a general characteristic of the galaxies in the Universe. Finally, we also show how the scale of each galaxy depends on a parameter determined by the final temperature of the SF galactic halo under study. This might explain why different galaxies with SFDM give different values of the mass of the SF.

astro-ph.GA↗

arXiv2024

Cosmic Acceleration from topological considerations III: Lie group

Recent observations on the large-scale structure of the universe indicate that the cosmological constant cannot be the definitive answer to the nature of dark energy. Therefore, it is a good time to propose alternatives to understand the late-accelerated expansion of the universe. In this work we study the possibility that the acceleration of space-time is due to the topology of the universe. We assume that the topology of the universe is a principal fiber bundle whose base space is our 4-dimensional spacetime and the fiber is an $N$-dimensional Lie group that evolves with time. For the base space we consider a homogeneous and isotropic spacetime, we find that the base space is currently accelerating for $1 < N$ compact semi-simple Lie groups whose scale-factors are equal and for $1 < N$ non-Abelian Lie groups whose scale-factors are different and as long as its structure constants satisfy some conditions. However when we study the evolution of the density parameters these differ from the evolution within the $Λ$CDM model, this led us to think in the possibility of use a different group as fiber in order to obtain the right evolution of the density parameters. We conclude that it is possible that the accelerated expansion of the universe is due to consider a different topology of the universe as a principal fiber bundle.

gr-qc↗

arXiv2024

General perturbations in D+1 standard and brane cosmology revisited

In the present work, we generalize the theory of perturbations in a D + 1 dimensional space-time with cosmological constant, studying scalar, vector and tensor perturbations, as well as its structure in Newtonian and Synchronous gauge. We also show the theory of perturbations in the context of brane cosmology, where branes are embedded in a set of D-spatial dimensions, a temporal dimension, and an additional spatial dimension. In both, standard and brane cosmology an unperturbed spacetime is provided with a Friedmann-Lemaitre-Robertson-Walker metric and arbitrary sectional curvature, the matter content has the shape of a perfect fluid. In addition, we consider the arbitrary sectional curvature, obtaining the respective equations in the Newtonian and Synchronous gauge. We highlight that the results presented in this article can be used to treat brane cosmology with two concentric branes or tackle the σ_{8} tension with a braneworld approach. Finally, as an example of the utility of all the technology presented in this paper, we show an application to the energy ux and the repercussions in the framework of the brane-worlds.

gr-qc↗

arXiv2023

Short Review of the main achievements of the Scalar Field, Fuzzy, Ultralight, Wave, BEC Dark Matter model

The Scalar Field Dark Matter model has been known in various ways throughout its history; Fuzzy, BEC, Wave, Ultralight, Axion-like Dark Matter, etc. All of them consist in proposing that the dark matter of the universe is a spinless field $Φ$ that follows the Klein-Gordon (KG) equation of motion $\BoxΦ-dV/dΦ=0$, for a given scalar field potential $V$. The difference between different models is sometimes the choice of the scalar field potential $V$. In the literature we find that people usually work in the nonrelativistic, weak-field limit of the KG equation where it transforms into the Schrödinger equation and the Einstein equations into the Poisson equation, reducing the KG-Einstein system, to the Schrödinger-Poisson system. In this paper, we review some of the most interesting achievements of this model from the historical point of view and its comparison with observations, showing that this model could be the last answer to the question about the nature of dark matter in the universe.

astro-ph.CO↗

arXiv2023

Cosmology on a Gravitational Wave Background

It is a fact that the universe lives on a Gravitational Wave Background (GWB), which it may be in the form of extra energy, which is not contained in Einstein's field equations. In \cite{Matos:2021jef}, a new model was developed to explain the current accelerating expansion of the universe where a GWB was incorporated by extending Einstein's equations to $R_{μν}-\frac{1}{2}Rg_{μν}+\frac{2π^2}{λ^2}g_{μν}=κ^2 T_{μν}$, where $λ$ is the Compton wavelength of the graviton. In the present work we show that this extended form agrees very well with the observations of Cosmic chronometers, Baryon Acoustic Oscillations and Pantheon SN type Ia, reproducing the observational data with a $Δχ^2=3.26$ in favor of the present model compared to the $Λ$CDM. The values favored by these observations are $Ω_{\rm m} = 0.31 \pm 0.02$, $H_0=68 \pm 0.02$ Km/s/Mpc, $Ω_{\rm k} = 0.001\pm 0.011$; we also find an excellent consistence of this model with the Cosmic Microwave Background and the Matter Power Spectrum. We conclude that this model is an excellent alternative to explain the accelerating expansion of the universe without incorporating the cosmological constant.

physics.gen-ph↗

arXiv2023

Analytic imaging formation analysis for Dark Matter halos: geometric ray tracing and caustics using the gravitational refraction law

One of the most challenging open questions in physics today is discovering the nature of dark matter. In this work we study the imaging formation in dark matter (DM) halos due to an external light source using some DM profiles for comparison with astronomical observations. Approaching these models on a small scale, we analyze the images generated on the lens plane by obtaining the analytical scaled surface mass densities $Σ_{*}(x)$ and their corresponding deflection angles $α_{*}(x)$, for later applying a method for ray tracing using the gravitational refraction law. The method is able to locate the positions of the images on the lens plane, by mapping fringes that represent possible sources (such as other galaxies), placed on the source plane. The regions where the strong lensing occurs for each profile, are determined by fixing the $λ$ parameter that establishes the ray tracing process. It is shown that the presence of Einstein rings generated by each profile is directly related with the central branch of the caustic. This method gives us a possible alternative way to distinguish between different DM candidates by observing imaging from external sources.

gr-qc↗

arXiv2023

Proca Stars with Dark Photons from Spontaneous Symmetry Breaking of the Scalar Field Dark Matter

Recently, the Scalar Field Dark Matter (SFDM) model (also known as Fuzzy, Wave, Bose-Einstein, Ultra-light Dark Matter) has gained a lot of attention because it has provided simpler and more natural explanations for various phenomena observed in galaxies, as a natural explanation for the center of galaxies, the number of satellite galaxies around their host and, more recently, a natural explanation for anomalous trajectories of satellite galaxies called Vast Polar Orbits (VPO) observed in various galaxies. In the present work we study the assumption that the SFDM is a type of charged dark boson whose gauge charge is associated with the Dark Photon (DP). Inspired by these results, we study the formation of compact bosonic objects, such as Boson Stars (BS) and focus on the possibility that, due to spontaneous $U(1)$ SFDM symmetry breaking, the DP may acquire mass and form compact objects like Proca Stars (PS). If this is true, we can expect measurable effects on the electromagnetic field of the Standard Model (SM) of particles due to their interaction with the DP on the formation of compact objects.

gr-qc↗

arXiv2023

Geodesic completeness of a ring wormhole

In this work the possible geodesic completeness of an electromagnetic dipole wormhole is studied in detail. The space-time contains a curvature singularity and belongs to a class of solutions to the Einstein-Maxwell equations with a coupled scalar field. Specifically, a numerical analysis is performed to examine congruences of null geodesics that are directed toward the singularity. The results found here show that, depending on the strength of the coupling between the scalar and electromagnetic fields, the wormhole can be either geodesically incomplete or complete. We then focus on those wormholes that are geodesically complete and study the geometry of the neighborhood of their singularity using Kaluza-Klein theory in a five-dimensional space-time. This process allows us to provide a possible explanation of the completeness of geodesics despite unbounded curvature.

gr-qc↗

arXiv2022

Cosmological constraints on the Multi Scalar Field Dark Matter model

The main aim of this paper is to provide cosmological constraints on the Multi Scalar Field Dark Matter model (MSFDM), in which we assume the dark matter is made up of different ultra-light scalar fields. As a first approximation, we consider they are real and do not interact with each other. We study the equations for both the background and perturbations for $N$-fields and present the evolution of the density parameters, the mass power spectrum and the CMB spectrum. In particular, we focus on two scalar fields with several combinations for the potentials $V(ϕ) = 1/2 m_ϕ^2 ϕ^2$, $V(ϕ) = m_ϕ^2f^2\left[1+\cos(ϕ/f)\right]$ and $V(ϕ) = m_ϕ^2f^2\left[\cosh(ϕ/f)-1\right]$, however the work, along with the code, could be easily extended to more fields. We use the data from BAO, Big Bang Nucleosynthesis, Lyman-$α$ forest and Supernovae to find constraints on the sampling parameters for the cases of a single field and double field, along with the Bayesian evidence. We found that some combinations of the potentials get penalized through the evidence, however for others there is a preference as good as for the cold dark matter.

astro-ph.CO↗

arXiv2022

The quantum character of the Scalar Field Dark Matter

The Scalar Field Dark Matter (SFDM) model, also called Fuzzy, Wave, Bose-Einstein, Ultra-light Dark Matter, has received a lot of attention because it has been able to provide simpler and more natural explanations for various features of galaxies, such as the number of satellite galaxies and the cusp-core problem. We recently showed that this model is able to explain the vast polar orbits of satellite galaxies around their host, the so-called VPO, and to explain the X-ray and gamma-ray emissions in the vacuum regions of our galaxy, that is, the Fermi Bubbles. In all these phenomena the quantum character of SFDM has been crucial. In this work we study the quantum effects of SFDM at the cosmological level, to see these effects not only at the galactic scale, but also at the cosmological scale. Using a convenient ansatz, we were able to integrate the perturbed equations to show that the shape of the SFDM halos resembling atoms is a generic result. The main conclusion of this work is that quantum mechanics, the successful microworld theory, could also explain the dark side of the cosmos.

astro-ph.CO↗

arXiv2022

Hydrodynamic representation and Energy Balance for Dirac and Weyl fermions in curved space-times

Using a generalized Madelung transformation, we derive the hydrodynamic representation of the Dirac equation in arbitrary curved space-times coupled to an electromagnetic field. We obtain Dirac-Euler equations for fermions involving a continuity equation and a first integral of the Bernoulli equation. Comparing between the Dirac and Klein-Gordon equations we obtain the balance equation for fermion particles. We also use the correspondence between fermions and bosons to derive the hydrodynamic representation of the Weyl equation which is a chiral form of the Dirac equation.

gr-qc↗