Person: Blázquez Salcedo, José Luis
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First Name
José Luis
Last Name
Blázquez Salcedo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física Teórica
Area
Física Teórica
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17 results
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Now showing 1 - 10 of 17
Item Angular momentum – area – proportionality of extremal charged black holes in odd dimensions(Physics Letters B, 2013) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lerida, FranciscoExtremal 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.Item 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, EugenWe 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.Item 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.Item 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.Item 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, EugenWe 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.Item Sequences of extremal radially excited rotating black holes(Physical Review Letters, 2014) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lerida, Francisco; Radu, EugenIn 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.Item 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, EugenWe 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.Item Charged rotating black holes in Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant(Physical review D, 2017) Blázquez Salcedo, José Luis; Kunz, Jutta; Navarro Lérida, Francisco; Radu, EugenWe consider rotating black hole solutions in five-dimensional Einstein-Maxwell-Chern-Simons theory with a negative cosmological constant and a generic value of the Chern-Simons coupling constant.. Using both analytical and numerical techniques, we focus on cohomogeneity-1 configurations, with two equal-magnitude angular momenta, which approach at infinity a globally anti-de Sitter background. We find that the generic solutions share a number of basic properties with the known Cvetic, Lu, and Pope black holes which have lambda = 1. New features occur as well; for example, when the Chern-Simons coupling constant exceeds a critical value, the solutions are no longer uniquely determined by their global charges. Moreover, the black holes possess radial excitations which can be labelled by the node number of the magnetic gauge potential function. Solutions with small values of. possess other distinct features. For instance, the extremal black holes there form two disconnected branches, while not all near-horizon solutions are associated with global solutions.Item Polar quasi-normal modes of neutron stars with equations of state satisfying the 2 M_0 constraint(Physical review D, 2014) Blázquez Salcedo, José Luis; González Romero, Luis Manuel; Navarro Lérida, F.In this paper, we analyze the quasinormal mode spectrum of realistic neutron stars by studying the polar modes. In particular, we calculate the fundamental mode (f mode), the fundamental pressure mode (p mode), and the fundamental curvature mode (wI mode) for 15 different equations of state satisfying the 2 M_0 constraint, most of them containing exotic matter. Since f and p modes couple to matter perturbations, the influence of the presence of hyperons and quarks in the core of the neutron stars is more significant than for the axial component. We present phenomenological relations, which are compatible with previous results, for the frequency and damping time with the compactness of the neutron star. We also consider new phenomenological relations between the frequency and damping time of the wI mode and the f mode. These new relations are independent of the equation of state and could be used to estimate the central pressure, mass, or radius and eventually constrain the equation-of-state of neutron stars. To obtain these results, we have developed a new method based on the exterior complex scaling technique with a variable angle.Item Quasinormal modes of Einstein-Gauss-Bonnet-dilaton black holes(Physical Review D, 2017) Blázquez Salcedo, José Luis; Khoo, Fech Scen; Kunz, JuttaWe study quasinormal modes of static Einstein-Gauss-Bonnet-dilaton black holes. Both axial and polar perturbations are considered and studied from l = 0 to l = 3. We emphasize the difference in the spectrum between the Schwarzschild solutions and dilatonic black holes. At large Gauss-Bonnet coupling constant, a small secondary branch of black holes is present, when the dilaton coupling is sufficiently strong. The modes of the primary branch can differ from the Schwarzschild modes up to 10%. The secondary branch is unstable and possesses long-lived modes. We address the possible effects of these modes on future observations of gravitational waves emitted during the ringdown phase of astrophysical black holes.