Susana Valdez-Alvarado

Obtaining mass parameters of compact objects from redshifts and blueshifts emitted by geodesic particles around them

The mass parameters of compact objects such as Boson Stars, Schwarzschild, Reissner Nordstrom and Kerr black holes are computed in terms of the measurable redshift-blueshift (zred, zblue) of photons emitted by particles moving along circular geodesics around these objects and the radius of their orbits. We found bounds for the values of (zred, zblue) that may be observed. For the case of Kerr black hole, recent observational estimates of SrgA\* mass and rotation parameter are employed to determine the corresponding values of these red-blue shifts.

Dynamical evolution of fermion-boson stars

Compact objects, like neutron stars and white dwarfs, may accrete dark matter, and then be sensitive probes of its presence. These compact stars with a dark matter component can be modeled by a perfect fluid minimally coupled to a complex scalar field (representing a bosonic dark matter component), resulting in objects known as fermion-boson stars. We have performed the dynamical evolution of these stars in order to analyze their stability, and to study their spectrum of normal modes, which may reveal the amount of dark matter in the system. Their stability analysis shows a structure similar to that of an isolated (fermion or boson) star, with equilibrium configurations either laying on the stable or on the unstable branch. The analysis of the spectrum of normal modes indicates the presence of new oscillation modes in the fermionic part of the star, which result from the coupling to the bosonic component through the gravity.

Evolution and stability ?4 oscillatons

We solve numerically the Einstein–Klein–Gordon (EKG) system, assuming spherical symmetry, for a real scalar field endowed with a quartic self-interaction potential, and obtain the so-called oscillatons: oscillating soliton stars. We obtain the equilibrium configurations for Φ4oscillatons. Also, we analyze numerically the evolution of the EKG equations to study the stability of such oscillatons. We present the influence of the quartic potential on the behavior of both the stable (S-oscillatons) and unstable (U-oscillatons) branches, under the influence of small and large radial perturbations.

Evolution of boson-fermion stars

The boson-fermion stars can be modeled with a complex scalar field coupled minimally to a perfect fluid (i.e., without viscosity and non-dissipative). We present a study of these solutions and their dynamical evolution by solving numerically the Einstein-Klein-Gordon-Hydrodynamic (EKGHD) system. It is shown that stable configurations exist, but stability of general configurations depends finely upon the number of bosons and fermions.

Evolution and stability Φ4oscillatons

We solve numerically the Einstein–Klein–Gordon (EKG) system, assuming spherical symmetry, for a real scalar field endowed with a quartic self-interaction potential, and obtain the so-called oscillatons: oscillating soliton stars. We obtain the equilibrium configurations for Φ4oscillatons. Also, we analyze numerically the evolution of the EKG equations to study the stability of such oscillatons. We present the influence of the quartic potential on the behavior of both the stable (S-oscillatons) and unstable (U-oscillatons) branches, under the influence of small and large radial perturbations.

Evolution and stability Φ4 oscillatons

We solve numerically the Einstein–Klein–Gordon (EKG) system, assuming spherical symmetry, for a real scalar field endowed with a quartic self-interaction potential, and obtain the so-called oscillatons: oscillating soliton stars. We obtain the equilibrium configurations for Φ4oscillatons. Also, we analyze numerically the evolution of the EKG equations to study the stability of such oscillatons. We present the influence of the quartic potential on the behavior of both the stable (S-oscillatons) and unstable (U-oscillatons) branches, under the influence of small and large radial perturbations.

Evolution and stability phi**4 oscillatons

We solve numerically the Einstein–Klein–Gordon (EKG) system, assuming spherical symmetry, for a real scalar field endowed with a quartic self-interaction potential, and obtain the so-called oscillatons: oscillating soliton stars. We obtain the equilibrium configurations for Φ4oscillatons. Also, we analyze numerically the evolution of the EKG equations to study the stability of such oscillatons. We present the influence of the quartic potential on the behavior of both the stable (S-oscillatons) and unstable (U-oscillatons) branches, under the influence of small and large radial perturbations.

Stability of ?4 oscillatons

We investigate the stability of oscillatons with a quartic self-interaction. Oscillatons are spherically symmetric solutions of the coupled Einstein-Klein-Gordon for the case of a real scalar field. It is shown that there exist equilibrium configurations which are stables under small and strong (radial) perturbations. Some basic numerical tools are implemented that shall help in the study of arbitrary equilibrium configurations.

Stability of Φ4 oscillatons

We investigate the stability of oscillatons with a quartic self-interaction. Oscillatons are spherically symmetric solutions of the coupled Einstein-Klein-Gordon for the case of a real scalar field. It is shown that there exist equilibrium configurations which are stables under small and strong (radial) perturbations. Some basic numerical tools are implemented that shall help in the study of arbitrary equilibrium configurations.

Equilibrium Configuration of {Phi}{sup 4} Oscillatons

We search for equilibrium configurations of the (coupled) Einstein‐Klein‐Gordon equations for the case of a real scalar field endowed with a quartic self‐interaction potential. The resulting solutions are the generalizations of the (massive) oscillating soliton stars, the so‐called oscillatons. Among other parameters, we estimate the mass curve of the configurations, and determine their critical mass for different values of the quartic interaction.