130 research outputs found
Extremal Charged Rotating Black Holes in Odd Dimensions
Employing higher order perturbation theory, we obtain charged rotating black
holes in odd dimensions, where the Einstein-Maxwell Lagrangian may be
supplemented with a Chern-Simons term. Starting from the Myers-Perry solutions,
we use the electric charge as the perturbative parameter, and focus on extremal
black holes with equal-magnitude angular momenta. For
Einstein-Maxwell-Chern-Simons theory with arbitrary Chern-Simons coupling
constant, we perform the perturbations up to third order for any odd dimension.
We discuss the physical properties of these black holes and study their
dependence on the charge. In particular, we show that the gyromagnetic ratio
of Einstein-Maxwell black holes differs from the lowest order perturbative
value , and that the first correction term to is universal.Comment: 24 pages, 3 figure
Liberalización de los Servicios de Alta Velocidad Ferroviaria en España: El Proceso de Apertura a la Competencia.
El objetivo de este trabajo es analizar la apertura a la competencia en España de los trenes de pasajeros de alta velocidad. Formalmente, la liberalización ferroviaria culminó en 2020 con la firma de contratos-marco con tres operadores (Renfe y dos nuevos entrantes), si bien la pandemia sanitaria ha retrasado las fechas planeadas y ha introducido mucha incertidumbre sobre cómo evolucionarå este mercado a corto y medio plazo. Tras realizar un anålisis de la movilidad en los corredores licitados en todos los modos de transporte, el principal reto identificado es que la nueva oferta prevista parece muy ambiciosa, incluso para la demanda anterior al COVID-19. Si se añaden ademås los probables cambios en la movilidad post-pandemia, nuestra principal conclusión es que un equilibrio con tres operadores ferroviarios ofertando servicios ferroviarios de alta velocidad en España parece altamente inestable.post-print976 K
Extremal Charged Rotating Dilaton Black Holes in Odd Dimensions
Employing higher order perturbation theory, we find a new class of charged
rotating black hole solutions of Einstein-Maxwell-dilaton theory with general
dilaton coupling constant. Starting from the Myers-Perry solutions, we use the
electric charge as the perturbative parameter, and focus on extremal black
holes with equal-magnitude angular momenta in odd dimensions. We perform the
perturbations up to 4th order for black holes in 5 dimensions and up to 3rd
order in higher odd dimensions. We calculate the physical properties of these
black holes and study their dependence on the charge and the dilaton coupling
constant.Comment: 20 pages, 3 figure
Radial excitations of non-static black holes in Einstein-Maxwell-Chern-Simons gravity
We study the generalization of the Kerr-Newmann black hole in 5D
Einstein-Maxwell-Chern-Simons theory with free Chern-Simons coupling parameter.
These black holes possess equal magnitude angular momenta and an event horizon
of spherical topology. We focus on the extremal case with zero temperature. We
find that, when the Chern-Simons coupling is greater than two times the
supergravity case, new branches of black holes are found which violate
uniqueness. In particular, a sequence of these black holes are non-static
radially excited solutions with vanishing angular momentum. They approach the
Reissner-Nordstr\"om solution as the excitation level increases.Comment: 6 pages, 2 figure
Vortices of SO(2) gauged Skyrmions in 2+1 dimensions
Vortices the SO(2) gauged planar Skyrme model, with a) only Maxwell, b) only Chern-Simons, and c) both Maxwell and Chern-Simons dynamics are studied systematically. In cases a) and b), where both models feature a single parameter λ (the coupling of the potential term), the dependence of the energy on λ is analysed. It is shown that the plots of the energy vs. λ feature discontinuities and branches. In case c), the emphasis is on the evolution of the topological charge, taking non-integer values. Throughout, the properties studied are contrasted with those of the corresponding Abelian Higgs models
New black holes in minimal gauged supergravity: Deformed boundaries and frozen horizons
A new class of black hole solutions of the five dimensional minimal gauged
supergravity is presented. They are characterized by the mass, the electric
charge, two equal magnitude angular momenta and the magnitude of the magnetic
potential at infinity. These black holes possess a horizon of spherical
topology; however, both the horizon and the sphere at infinity can be
arbitrarily squashed, with nonextremal solutions interpolating between black
strings and black branes. A particular set of extremal configurations
corresponds to a new one-parameter family of supersymmetric black holes. While
their conserved charges are determined by the squashing of the sphere at
infinity, these supersymmetric solutions possess the same horizon geometry.Comment: 5 pages, 4 figures; v3: typos corrected, refs added; matches
published versio
D=5 Einstein-Maxwell-Chern-Simons Black Holes
5-dimensional Einstein-Maxwell-Chern-Simons theory with Chern-Simons
coefficient has supersymmetric black holes with vanishing horizon
angular velocity, but finite angular momentum. Here supersymmetry is associated
with a borderline between stability and instability, since for a
rotational instability arises, where counterrotating black holes appear, whose
horizon rotates in the opposite sense to the angular momentum. For
black holes are no longer uniquely characterized by their global charges, and
rotating black holes with vanishing angular momentum appear.Comment: 4 pages, 4 figures, RevTeX styl
Non-uniqueness, Counterrotation, and Negative Horizon Mass of Einstein-Maxwell-Chern-Simons Black Holes
Stationary black holes in 5-dimensional Einstein-Maxwell-Chern-Simons theory
possess surprising properties. When considering the Chern-Simons coefficient
as a parameter, two critical values of appear: the
supergravity value , and the value . At
, supersymmetric black holes with vanishing horizon angular
velocity, but finite angular momentum exist. As increases beyond
a rotational instability arises, and counterrotating black
holes appear, whose horizon rotates in the opposite sense to the angular
momentum. Thus supersymmetry is associated with the borderline between
stability and instability. At rotating black holes with vanishing
angular momentum emerge. Beyond black holes may possess a negative
horizon mass, while their total mass is positive. Charged rotating black holes
with vanishing gyromagnetic ratio appear, and black holes are no longer
uniquely characterized by their global charges.Comment: 15 pages, 16 figures, MPLA style, invited review for Modern Physics
Letters
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