Person:
Blázquez Salcedo, José Luis

First Name

José Luis

Last Name

Blázquez Salcedo

URI

https://hdl.handle.net/20.500.14352/75158

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física Teórica

Area

Física Teórica

Identifiers

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Now showing 1 - 10 of 27

Are slowly rotating Ellis-Bronnikov wormholes stable?
(Physics Letters B, 2024) Azad, Bahareh; Blázquez Salcedo, José Luis; Khoo, Fech Scen; Kunz, Jutta
We investigate the radial perturbations of Ellis-Bronnikov wormholes (l = 0) in a slowly rotating background expanded up to second order in rotation. We find indications that simple wormhole solutions such as Ellis-Bronnikov in General Relativity can be stabilized by rotation, thus favoring a viable traversable wormhole. This opens up the intriguing question whether the many other wormhole solutions with or without the support of exotic matter can become linearly mode stable when the wormhole rotates.
Polar modes and isospectrality of Ellis-Bronnikov wormholes
(Physical review D, 2023) Azad, Bahareh; Blázquez Salcedo, José Luis; Chew, Xiao Yan; Kunz, Jutta; Yeom, Dong-han
We consider polar perturbations of static Ellis-Bronnikov wormholes and derive the coupled set of perturbation equations for the gravitational and the scalar field. For massless wormholes the perturbations decouple, and we obtain two identical master equations for the scalar and gravitational modes, which moreover agree with the master equation for the axial modes. Consequently there is isospectrality with threefold degenerate modes. For a finite mass of the background wormhole solutions, the equations are coupled. We then obtain two distinct branches of polar quasinormal modes for a given multipole number l, associated with the presence of the two types of fields. We calculate the quasinormal mode frequencies and decay rates for the branches with l = 2, 3 and 4. For a given l the real frequencies of the two branches get the closer, the higher the multipole number gets.
Traversable wormholes in Einstein-Dirac-Maxwell theory
(Physical Review Letters, 2021) Blázquez Salcedo, José Luis; Knoll, Christian; Radu, Eugen
We construct a specific example of a class of traversable wormholes in Einstein-Dirac-Maxwell theory in four spacetime dimensions, without needing any form of exotic matter. Restricting to a model with two massive fermions in a singlet spinor state, we show the existence of spherically symmetric asymptotically flat configurations which are free of singularities, representing localized states. These solutions satisfy a generalized Smarr relation, being connected with the extremal Reissner-Nordström black holes. They also possess a finite mass M and electric charge Q_e, with Q_e/M > 1. An exact wormhole solution with ungauged, massless fermions is also reported.
Angular momentum – area – proportionality of extremal charged black holes in odd dimensions
(Physics Letters B, 2013) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lerida, Francisco
Extremal rotating cohomogeneity-1 black holes in Einstein-Maxwell theory feature two branches. On the branch emerging from the Myers-Perry solutions their angular momentum is proportional to their horizon area, while on the branch emerging from the Tangherlini solutions their angular momentum is proportional to their horizon angular momentum. The transition between these branches occurs at a critical value of the charge, which depends on the value of the angular momentum. However, when a dilaton is included, the angular momentum is always proportional to the horizon area.
Remarks on the Taub-NUT solution in Chern–Simons modified gravity
(Physics letters B, 2017) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lérida, Francisco; Radu, Eugen
We construct a generalization of the AdS charged rotating black holes with two equal magnitude angular momenta in five-dimensional minimal gauged supergravity. In addition to the mass, electric charge and angular momentum, the new solutions possess an extra-parameter associated with a non-zero magnitude of the magnetic potential at infinity. In contrast with the known cases, these new black holes possess a non-trivial zero-horizon size limit which describes a one parameter family of spinning charged solitons. All configurations reported in this work approach asymptotically an AdS(5) spacetime in global coordinates and are free of pathologies.
Radial perturbations of the scalarized Einstein-Gauss-Bonnet black holes
(Physical Review D, 2018) Blázquez Salcedo, José Luis; Doneva, Daniela D.; Kunz, Jutta; Yazadyiev, Stoytcho S.
Recently a new class of scalarized black holes in Einstein-Gauss-Bonnet (EGB) theories was discovered. What is special for these black hole solutions is that the scalarization is not due to the presence of matter, but it is induced by the curvature of spacetime itself. Moreover, more than one branch of scalarized solutions can bifurcate from the Schwarzschild branch, and these scalarized branches are characterized by the number of nodes of the scalar field. The next step is to consider the linear stability of these solutions, which is particularly important due to the fact that the Schwarzschild black holes lose stability at the first point of bifurcation. Therefore we here study in detail the radial perturbations of the scalarized EGB black holes. The results show that all branches with a nontrivial scalar field with one or more nodes are unstable. The stability of the solutions on the fundamental branch, whose scalar field has no radial nodes, depends on the particular choice of the coupling function between the scalar field and the Gauss-Bonnet invariant. We consider two particular cases based on the previous studies of the background solutions. If this coupling has the form used in [D. D. Doneva and S. S. Yazadjiev, Phys. Rev. Lett. 120, 131103 (2018)] the fundamental branch of solutions is stable, except for very small masses. In the case of a coupling function quadratic in the scalar field [H. O. Silva, J. Sakstein, L. Gualtieri, T. P. Sotiriou, and E. Berti, Phys. Rev. Lett. 120, 131104 (2018)], though, the whole fundamental branch is unstable.
Non-Abelian Chern-Simons-Higgs vortices with a quartic potential
(Physical review D, 2013) Blázquez Salcedo, José Luis; González Romero, Luis Manuel; Navarro Lerida, Francisco; Tchrakian, D. H.
We have constructed numerically non-Abelian vortices in an SU(2) Chern-Simons-Higgs theory with a quartic Higgs potential. We have analyzed these solutions in detail by means of improved numerical codes and found some unexpected features we did not find when a sixth-order Higgs potential was used. The generic non-Abelian solutions have been generated by using their corresponding Abelian counterparts as initial guess. Typically, the energy of the non-Abelian solutions is lower than that of the corresponding Abelian one (except in certain regions of the parameter space). Regarding the angular momentum, the Abelian solutions possess the maximal value, although there exist non-Abelian solutions which reach that maximal value too. In order to classify the solutions it is useful to consider the non-Abelian solutions with asymptotically vanishing A_t component of the gauge potential, which may be labeled by an integer number m. For vortex number n = 3 and above, we have found uniqueness violation: two different nonAbelian solutions with all the global charges equal. Finally, we have investigated the limit of infinite Higgs self- coupling parameter and found a piecewise Regge-like relation between the energy and the angular momentum.
Squashed, magnetized black holes in D=5 minimal gauged supergravity
(Journal of high energy physics, 2018) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lérida, Francisco; Radu, Eugen
We construct a new class of black hole solutions in five-dimensional Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant. These configurations are cohomogeneity-1, with two equal-magnitude angular momenta. In the generic case, they possess a non-vanishing magnetic potential at infinity with a boundary metric which is the product of time and a squashed three-dimensional sphere. Both extremal and non-extremal black holes are studied. The non-extremal black holes satisfying a certain relation between electric charge, angular momenta and magnitude of the magnetic potential at infinity do not trivialize in the limit of vanishing event horizon size, becoming particle-like (non-topological) solitonic configurations. Among the extremal black holes, we show the existence of a new one-parameter family of supersymmetric solutions, which bifurcate from a critical Gutowski-Reall configuration.
Sequences of extremal radially excited rotating black holes
(Physical Review Letters, 2014) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lerida, Francisco; Radu, Eugen
In the Einstein-Maxwell-Chern-Simons theory the extremal Reissner-Nordstrom solution is no longer the single extremal solution with vanishing angular momentum, when the Chern-Simons coupling constant reaches a critical value. Instead a whole sequence of rotating extremal J = 0 solutions arises, labeled by the node number of the magnetic U(1) potential. Associated with the same near horizon solution, the mass of these radially excited extremal solutions converges to the mass of the extremal Reissner-Nordstrom solution. On the other hand, not all near horizon solutions are also realized as global solutions.
Static Einstein-Maxwell magnetic solitons and black holes in an odd dimensional AdS spacetime
(Entropy, 2016) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lérida, Francisco; Radu, Eugen
We construct a new class of Einstein-Maxwell static solutions with a magnetic field in D-dimensions (with D >= 5 an odd number), approaching at infinity a globally Anti-de Sitter (AdS) spacetime. In addition to the mass, the new solutions possess an extra-parameter associated with a non-zero magnitude of the magnetic potential at infinity. Some of the black holes possess a non-trivial zero-horizon size limit, which corresponds to a solitonic deformation of the AdS background.