BLACK HOLES
Black holes are objects whose gravitational field is so strong that nothing can space from it, including light. They are believed to be the remants of gravitationally collapsed stars whose nuclear fuel has been exhausted and whose mass is above the Chandrasekhar bound. According to a set of well established results black holes share three properties: i) they are solely described by three parameters (mass, charge and angular momentum), ii) a horizon sets a one-way membrane limiting the region of the black hole from which nothing can escape and iii) a singularity dwells at the center of the black hole. Moreover, black holes provide an interesting playground for testing a number of theoretical ideas.
My own research is aimed at a theoretical analysis of black holes regarding five large issues: i) modification of black hole structure in its innermost region due to new effects of gravity and matter in static and rotating settings; ii) singularity avoidance, regular solutions, geodesic behaviour, effect of tidal forces, scattering experiments of waves (scalar and fermions) and meaning and relation between curvature divergences and space-time singularities; iii) gravitational collapse regarding new quantum gravity-induced effects in the last stages of the process, iv) dynamical generation of these objects in scenarios with fluxes of particles, (anisotropic) fluids or large magnetic fields; and v) thermodynamic aspects of black holes/branes, including new thermodynamic laws within modified gravity and new behaviours of the thermodynamic variables, and Hawking's radiation and black hole evaporation process.
MODIFIED THEORIES OF GRAVITY
Despite the great experimental success of Einstein's General Theory of Relativity (GR), the limitations of the $\Lambda$CDM matter to describe the pre-inflationary universe and the innermost regions of black holes, where the QG effects can no longer be neglected, the difficulty to explain the recent cosmic accelerated expansion, and the lack of direct experimental support for dark matter particles suggest that the model is just an effective description that requires certain extensions of the underlying gravitational theory in both the ultraviolet and infrared sectors.
Following well-established results from the theory of quantized fields in curved space-times and the low-energy limit of certain approaches to QG like string theory, my main line of work is to investigate classical extensions of GR containing higher-order curvature corrections. In this context, like the number of space-time dimensions, the question of whether the metric and affine structures of spacetime are independent (metric-affine approach) or if the affine structure is determined by the metric structure (Riemannian approach), is a foundational issue of gravity as a geometric phenomenon, which has however received little attention so far. The goal of my research is to get insights on both black hole physics and cosmology and aimed, very broadly, to modifications of black hole structure/singularities/dynamics/thermodynamics, and modifications of the standard cosmological picture in bouncing solutions/inflation/dark matter candidates/dark energy scenarios.
WORMHOLES AND SPACE-TIME SINGULARITIES
Wormhole are hypothetical bridges connecting different parts of the Universe that arise as solutions of GR when violations of the energy conditions are assumed, which is physically troublesome. However, such violations are not necessary in the context of modified gravity. Working in Palatini formalism, a generic prediction is that the GR point-like singularity is generically replaced by a wormhole structure supported by an electromagnetic field. Such wormholes can resolve black hole singularities without necessarily removing curvature divergences, as an analysis of geodesic completeness and congruence of geodesics suggests. Such a result deserves further exploration, for example, through probing with waves. Nonetheless, curvature divergences are absent for a certain mass-to-charge ratio, and the horizon disappear when the number of charges drops below a certain bound (microscopic black hole remnants). What are the implications regarding our understanding of particles and fields, the sources problem, and the energy definition/localization problem?. It is also important to investigate if other particle properties (e.g.color charges or spin) can be reproduced adding other free gauge fields.
In the context of modified gravity, one can consider extensions of the standard cosmological $\Lambda$CDM model picture, in particular through bouncing solutions (replacing the Big Bang singularity) and their robustness in different theories, and new inflationary scenarios. Such extensions generically produce an effective cosmological constant at low energies. In addition, I look for alternatives to the dark matter/energy paradigms are studied. For example, the existence of charged horizonless microscopic black holes (which are fully compatible with Hawking's estimates of mass and charge for generation of primordial black holes in the early Universe) in metric-affine models could have a substantial impact in accounting for the matter density of the hypothesized dark matter particles. One should obtain precise estimates of the abundances of such objects in stable states, which might be produced through evaporation of larger black holes or arise directly from the early Universe.
COSMOLOGY
Topological defects are solutions of (non-linear) field theories that interpolate between different vacua. Strongly constrained by Derrick's theorem and by the difficulty to obtain analytic solutions, generalized models of scalar and vector fields have been widely considered in the literature. Part of my research is aimed at the development of such models for the application of their topological defect solutions in different contexts, including cosmology and high-energy physics.
TOPOLOGICAL DEFECTS
I am interested on the following topics: Gravitation, theoretical black hole physics, modified theories of gravity, metric-affine gravity, mathematical/geometrical methods, exact solutions, semiclassical quantum gravity, wormholes, Cosmology, higher-dimensional gravity, braneworlds, nonlinear models of matter, topological defects.