arXiv subjects

Francisco S. Guzman

Publications and source records attributed to Francisco S. Guzman.

13 recordsLinked to original sources

arXiv2026

Accretion of multipolar massive complex scalar field packets by a Schwarzschild black hole

We study the finite-time accretion of complex massive scalar wave packets by a Schwarzschild black hole in the test-field regime, with parameters motivated by ultralight fuzzy dark matter around supermassive black holes. Our goal is to determine how the scalar content of a localized configuration is redistributed after interacting with the black hole, and which spectral and multipolar components are more efficiently absorbed. We decompose the Klein--Gordon field into independent multipolar sectors and evolve nearly monochromatic Gaussian packets mode by mode, reducing the problem to a set of 1+1 dimensional evolutions. Accretion is quantified with the flux of the conserved Noether current through the horizon surface, providing a direct measure of the scalar charge absorbed by the black hole. For a carrier radial wavenumber $k_0$ and multipole index $\ell$, we construct accretion-efficiency maps in the $(k_0,\ell)$ plane that contain the fraction of accreted modal charge. These maps exhibit a transition between inefficient, partial, and efficient accretion regimes, which we relate to the structure of an effective potential. We show that the process is controlled by the ratio between the Schwarzschild radius $R_s$ and the reduced Compton wavelength $\lambdabar_C$. For $R_s \lesssim \lambdabar_C$, the transition is broad and dominated by the angular momentum barrier, while for $R_s > \lambdabar_C$ it sharpens across a narrower range of $k_0$ and a partial-accretion floor emerges at low $k_0$. These results provide a time-domain, Noether-charge-based classification of black hole accretion for massive scalar wave packets.

gr-qc↗

arXiv2026

Temporal Correlations Between Fuzzy Dark Matter and Baryonic Matter in Virialized Core-Halo Structures

Fuzzy Dark Matter (FDM) predicts the existence of virialized halos with interference-driven granular structure generated by the wave nature of ultralight bosons. Since these fluctuations produce time-dependent gravitational fields, they can be proposed as a potential source of observable dynamical effects on baryonic matter. In this work we test whether such fluctuations generate measurable temporal correlations between FDM and a coupled gas component. We evolve coupled FDM-gas configurations with the Schrödinger-Poisson-Euler system in three dimensions. The FDM component is initialized through multimerger configurations that relax toward core-halo structures, while the baryonic component is modeled as an ideal gas. After virialization, we analyze the temporal fluctuations of both components through correlation functions and spectral diagnostics. The FDM density field shows fluctuations with significant high-frequency content, whereas the gas develops smoother and longer-lived coherent structures. Although the gas dynamically responds to the gravitational potential generated by the FDM halo, we find no strong temporal correlation between the interference-driven fluctuations of FDM and the gas dynamics. This behavior persists across the explored range of gas temperatures. Our results indicate that baryonic matter reacts to the global gravitational potential of the virialized halo rather than to the detailed phase-dependent granular structure of FDM. This weak temporal coupling may limit the possibility of directly detecting FDM granularity through local baryonic temporal fluctuations.

astro-ph.GA↗

arXiv2026

Equilibrium Core and Vortex Solutions of Bose Einstein Condensate Dark Matter around a Black Hole

We present the construction of stationary solutions of Bose-Einstein condensate dark matter (BECDM) around a point-like gravitational source representing a black hole. The problem is formulated for general axisymmetric configurations, and we focus on two cases: the ground-state core solution and the first nonzero winding number configuration corresponding to a line vortex solution. The stationary equations are solved using an imaginary-time approach, which enables the construction of families of solutions across a wide range of self-interaction and black hole masses. We analyze the impact of these parameters on the density distribution and on the stability properties of the solutions, assessing stability through the turning point criterion based on the enthalpy functional, which allows us to identify stable and unstable branches along each family of solutions. It has been shown in the past that spherical core solutions act as attractors in the collapse of BECDM around black holes in the non-interacting case ($g=0$), supporting their astrophysical relevance. In the present work, the existence of a maximum mass for configurations with attractive self-interaction ($g<0$) allows us to infer the parameter range in which such solutions may also arise in this regime. Building on this picture, we show that stable vortex solutions of BECDM can also exist in the presence of a black hole, whose stability properties suggest that these configurations may likewise be compatible with physically relevant formation scenarios.

astro-ph.GA↗

arXiv2026

Effects of Self-Interaction and of an Ideal Gas in Binary Mergers of Bosonic Dark Matter Cores

We study binary mergers of dark matter cores in the Bose-Einstein condensate (BECDM) model. We include two scenarios: scalar self-interaction and the presence of a gravitationally coupled ideal gas. Using 3D simulations of the Gross-Pitaevskii-Poisson and Schrödinger-Poisson-Euler systems, we analyze the properties of the resulting remnants. We find that the final core-mass ratio reaches a stable average value after the merger. Repulsive self-interaction increases the mass of the final solitonic core, while attractive interaction enhances mass loss. In mergers involving an ideal gas, namely of fermion-boson stars, a stable solitonic core always forms in the bosonic component, even when the gas dominates, whereas the gas itself does not form a compact core. We explain these results using energy scalings and find that without self-interaction, equilibrium cores follow $E \propto -M^3$, which leads to an almost universal merger fraction. Self-interaction changes this scaling, because repulsive $g$ moves the system toward a milder $E \propto -M^2$ scaling and increases mass retention, while attractive $g$ strengthens binding and favors mass ejection. In the case of interaction with an ideal gas, this component only modifies the gravitational background and does not change the intrinsic scaling of the bosonic part. These results show that the merger outcome is not universal but controlled by the interaction strength, while solitonic BECDM cores remain robust across diverse environments including gas.

astro-ph.CO↗

arXiv2025

Fermion-Boson Stars as Attractors in Fuzzy Dark Matter and Ideal Gas Dynamics

In the context of Fuzzy Dark Matter (FDM) we study the core formation in the presence of an Ideal Gas (IG). Our analysis is based on the solution of the Schrödinger-Poisson-Euler system of equations that drives the evolution of FDM together with a compressible IG, both coupled through the gravitational potential they produce. Starting from random initial conditions for both FDM and IG, we study the evolution of the system until it forms a nearly relaxed, virialized and close to hydrostatic equilibrium core, surrounded by an envelope of the two components. We find that the core corresponds to Newtonian Fermion-Boson Stars (FBS). If the IG is used to model luminous matter, our results indicate that FBS behave as attractor core solutions of structure formation of FDM along with visible matter.

astro-ph.CO↗

arXiv2025

Black Holes as Condensation Points of Fuzzy Dark Matter Cores

We simulate the formation of Fuzzy Dark Matter (FDM) cores in the presence of a Black Hole (BH) to explore whether BHs can serve as seeds for FDM core condensation. Our analysis is based on the core-condensation via the kinetic relaxation process for random initial conditions of the FDM. In a generic scenario the BH merges with a pre-collapsed mini-cluster formed in a random location, once they share location the core-condensation starts withe the FDM density centered at the black hole that during the process acquires a profile consistent with that of the stationary solution of the FDM+BH eigenvalue problem. These results indicate that BHs can indeed act as focal points for FDM core condensation. Furthermore, we find that the central density of the resulting FDM core depends on the mass of the BH, which due to its permanent motion relative to the FDM core during the evolution, produces a smaller core density for bigger BH masses; in this way the BH mass is a parameter leading to a new diversity of central FDM core densities. As a collateral result, for our analysis we revised the construction of stationary solutions of FDM+BH and found a phenomenological formula for the FDM density that can be used to fit FDM cores around BHs.

astro-ph.GA↗

arXiv2025

Stability of multi-state configurations of fuzzy dark matter

We study the stability properties of multi-state configurations of the Schrödinger-Poisson system without self-interaction, with monopolar and first dipolar components $(1,0,0)$+$(2,1,0)$. We show these configurations studied are stable using numerical simulations, and using criteria of stationarity, unitarity and time dependence consistency. The study covers a range of states with monopolar to dipolar mass ratio between 47 and 0.17. The astrophysical implication of this result is that this type of configurations is at least stable and can be considered physically sound in multi-state ultralight bosonic dark matter.

gr-qc↗

arXiv2025

Unveiling Orbital Chaos: The Wild Heart of Fuzzy Dark Matter Structures

In this paper we study the behavior of test particles on top of a galactic-type of Fuzzy Dark Matter (FDM) structure, characterized by the core-halo density profile found in simulations. Our workhorse structure is an anisotropic, time-dependent, virialized core-tail FDM clump resulting from a multicore merger. For our analysis we allow this structure to keep evolving, which implies that the core oscillates and accretes matter from the halo, while the halo dynamics is dominated by its characteristic high kinetic energy. On top of this time-dependent structure that in turn has a time-dependent gravitational potential, we solve the motion equations of test particles with initial conditions associated to circular orbits at different radii. Our results indicate that: 1) no trajectory remains circular, 2) the trajectories are sensitive to initial conditions and 3) the departure of initially near trajectories has always a positive Lyapunov exponent. A qualitative result is that the motion of test particles is more erratic with a bigger Lyapunov exponent within and near the core than in the halo region, which can be understood in terms of the random motion of the core within the core-halo structure. We expect these results warn on the importance of the anisotropic and time-dependent nature of FDM clumps when studying the motion of test particles.

astro-ph.GA↗

arXiv2024

Numerical Solution Partial Differential Equations using the Discrete Fourier Transform

In this paper we explain how to use the Fast Fourier Transform (FFT) to solve partial differential equations (PDEs). We start by defining appropriate discrete domains in coordinate and frequency domains. Then describe the main limitation of the method arising from the Sampling Theorem, which defines the critical Nyquist frequency and the aliasing effect. We then define the Fourier Transform (FT) and the FFT in a way that can be implemented in one and more dimensions. Finally, we show how to apply the FFT in the solution of PDEs related to problems involving two spatial dimensions, specifically the Poisson equation, the diffusion equation and the wave equation for elliptic, parabolic and hyperbolic cases respectively.

math.NA↗

arXiv2024

Variational Quantum Crank-Nicolson and Method of Lines for the Solution of Initial Value Problems

In this paper we use a Variational Quantum Algorithm to solve Initial Value Problems with the Implicit Crank-Nicolson and the Method of Lines (MoL) evolution schemes. The unknown functions use a spectral decomposition with the Fourier basis. The examples developed to illustrate the implementation are the Advection equation, the wave equation written as a system of first order coupled equations and the viscous Burgers equation as a non-linear case. The problems are solved using: i) standard Finite Differences as the solution to compare with, ii) the State Vector Formalism (SVF), and iii) the Sampling Error Formalism (SEF). The contributions of this paper include: 1) cost functions for generic first order in time PDEs using the implicit Crank-Nicholson and the MoL, 2) detailed convergence or self-convergence tests are presented for all the equations solved, 3) a system of three coupled PDEs is solved, 4) solutions using sampling error are presented, which highlights the importance of simulating the sampling process and 5) a fast version of the SVF and SEF was developed which can be used to test different optimizers faster.

quant-ph↗

arXiv2024

Galactic Rotation Curves of LSB Galaxies using core-halo FDM configurations

In this work, we construct galactic halos in order to fit the rotation curves (RCs) of a sample of low surface brightness (LSB) galaxies. These halos are made of Fuzzy Dark Matter (FDM) with a multimode expansion of non-spherical modes that in average contribute to the appropriate density profile consisting of a core and an envelope needed to fit the rotation curves. The coefficients of the expansion are calculated using a genetic algorithm, that minimizes the difference between the spatial average density of the multimode order parameter describing the FDM and the target dark matter density that fits the RCs. The FDM halos are constructed assuming a solitonic core at the center and two types of envelopes, Navarro-Frenk-White and Pseudo-Isothermal density profiles. The resulting FDM configurations are then evolved in order to show how the average density changes in time due to the secular dynamical evolution, along with a condensation process that lead to the growth of the solitonic core.

astro-ph.GA↗

arXiv2024

Simulation of Gaussian Wave Packets used to Illustrate Elementary Quantum Mechanics Scenarios

In this paper we numerically solve the time dependent Schrödinger equation for scenarios using wave packets. These examples include the free wave packet, which we use to show the difference between group and phase velocities, the packet in a harmonic oscillator potential with non-trivial initial conditions in one and two dimensions, which is compared with their classical analogs to show how Ehrenfest theorem holds. We also include simulations of the diffraction through the single and double slit potentials, the refraction with a step potential and the dispersion by a central potential. The aim of this paper is to illustrate with simulations, nowadays easy to implement, scenarios that can help explaining the basics of the wave-particle duality.

physics.ed-ph↗

arXiv2022

Possible formation mechanism of multistate gravitational atoms

The collision of two equilibrium ground state solutions of the Schrödinger-Poisson (SP) system, in orthogonal states, is proposed as a formation mechanism of mixed state solutions of the SP system with spherical and first dipolar components. The collisions are simulated by solving numerically the SP system for two orthogonal states, considering head-on encounters, and using various mass ratios between the initial configurations with different head-on momentum. The results indicate that the less massive of the configurations pinches-off the more massive one, and redistributes its density along the axis of collision. The averaged in time density of the two states resembles the distribution of matter of bi-state equilibrium configurations with monopolar and dipolar contributions.

gr-qc↗