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Boson and Dirac stars in D ≥ 4 dimensions
https://repo.scoap3.org/record/32346
We present a comparative study of spherically symmetric, localized, particle-like solutions for spin s=0,1/2 and 1 gravitating fields in a D -dimensional, asymptotically flat spacetime. These fields are massive, possessing a harmonic time dependence and no self-interaction. Special attention is paid to the mathematical similarities and physical differences between the bosonic and fermionic cases. We find that the generic pattern of solutions is similar for any value of the spin s , depending only on the dimensionality of spacetime, the cases D=4,5 being special.Blázquez-Salcedo, Jose LuisWed, 17 Apr 2019 13:23:52 GMThttps://repo.scoap3.org/record/32346urn:ISSN:0370-2693Elsevier2019-05-20Kerr black holes with synchronised scalar hair and higher azimuthal harmonic index
https://repo.scoap3.org/record/32067
Kerr black holes with synchronised scalar hair and azimuthal harmonic index m>1 are constructed and studied. The corresponding domain of existence has a broader frequency range than the fundamental m=1 family; moreover, larger ADM masses, M and angular momenta J are allowed. Amongst other salient features, non-uniqueness of solutions for fixed global quantities is observed: solutions with the same M and J co-exist, for consecutive values of m , and the ones with larger m are always entropically favoured. Our analysis demonstrates, moreover, the qualitative universality of various features observed for m=1 solutions, such as the shape of the domain of existence, the typology of ergo-regions, and the horizon geometry, which is studied through its isometric embedding in Euclidean 3-space.Delgado, Jorge F.M.Tue, 09 Apr 2019 15:22:54 GMThttps://repo.scoap3.org/record/32067urn:ISSN:0370-2693Elsevier2019-05-10On the topological charge of SO (2) gauged Skyrmions in 2 + 1 and 3 + 1 dimensions
https://repo.scoap3.org/record/31447
The question of the dependence of the topological charge q of a gauged Skyrmion, on the gauge field, is studied quantitatively. Two examples, both gauged with SO(2) are studied and contrasted: i) The O(3) model in 2+1 dimensions, and ii) The O(4) model in 3+1 dimensions. In case i) , where the (usual) Chern–Simons (CS) term is present, the value of q changes sign, going through zero. This evolution is tracked by a parameter characterising the solutions in the given theory. In case ii) , in which dimensions no CS density is available, the evolution of q is not observed.Navarro-Lérida, FranciscoThu, 07 Mar 2019 14:16:00 GMThttps://repo.scoap3.org/record/31447urn:ISSN:0370-2693Elsevier2019-04-10Compact objects and the swampland
https://repo.scoap3.org/record/30707
Recently, two simple criteria were proposed to assess if vacua emerging from an effective scalar field theory are part of the string “landscape” or “swampland”. The former are the vacua that emerge from string compactifications; the latter are not obtained by any such compactification and hence may not survive in a UV completed theory of gravity. So far, these criteria have been applied to inflationary and dark energy models. Here we consider them in the context of solitonic compact objects made up of scalar fields: boson stars. Analysing several models (static, rotating, with and without self-interactions), we find that, in this context, the criteria are not independent. Furthermore, we find the universal behaviour that in the region wherein the boson stars are expected to be perturbatively stable, the compact objects may be part of the landscape. By contrast, in the region where they may be faithful black hole mimickers, in the sense they possess a light ring, the criteria fail (are obeyed) for static (rotating) ultracompact boson stars, which should thus be part of the swampland (landscape). We also consider hairy black holes interpolating between these boson stars and the Kerr solution and establish the part of the domain of existence where the swampland criteria are violated. In interpreting these results one should bear in mind, however, that the swampland criteria are not quantitatively strict.Herdeiro, CarlosThu, 31 Jan 2019 12:35:10 GMThttps://repo.scoap3.org/record/30707urn:ISSN:1029-8479Springer/SISSA2019-01-29The scalarised Schwarzschild-NUT spacetime
https://repo.scoap3.org/record/29193
It has recently been suggested that vacuum black holes of General Relativity (GR) can become spontaneously scalarised when appropriate non-minimal couplings to curvature invariants are considered. These models circumvent the standard black hole no scalar hair theorems of GR, allowing both the standard GR solutions and new scalarised (a.k.a. hairy) solutions, which in some cases are thermodynamically preferred. Up to now, however, only (static and spherically symmetric) scalarised Schwarzschild solutions have been considered. It would be desirable to take into account the effect of rotation; however, the higher curvature invariants introduce a considerable challenge in obtaining the corresponding scalarised rotating black holes. As a toy model for rotation, we present here the scalarised generalisation of the Schwarzschild-NUT solution, taking either the Gauss–Bonnet (GB) or the Chern–Simons (CS) curvature invariant. The NUT charge n endows spacetime with “rotation”, but the angular dependence of the corresponding scalarised solutions factorises, leading to a considerable technical simplification. For GB, but not for CS, scalarisation occurs for n=0 . This basic difference leads to a distinct space of solutions in the CS case, in particular exhibiting a double branch structure. In the GB case, increasing the horizon area demands a stronger non-minimal coupling for scalarisation; in the CS case, due to the double branch structure, both this and the opposite trend are found. We briefly comment also on the scalarised Reissner–Nordström-NUT solutions.Brihaye, YvesThu, 15 Nov 2018 10:17:14 GMThttps://repo.scoap3.org/record/29193urn:ISSN:0370-2693Elsevier2019-01-10Non-perturbative spinning black holes in dynamical Chern–Simons gravity
https://repo.scoap3.org/record/28720
Spinning black holes in dynamical Einstein–Chern–Simons gravity are constructed by directly solving the field equations, without resorting to any perturbative expansion. This model is obtained by adding to the Einstein–Hilbert action a particular higher-curvature correction: the Pontryagin density, linearly coupled to a scalar field. The spinning black holes are stationary, axi-symmetric, asymptotically flat generalisations of the Kerr solution of Einstein's gravity, but they possess a non-trivial (odd-parity) scalar field. They are regular on and outside the horizon and satisfy a generalized Smarr relation. We discuss the deviations from Kerr at the level of the spin and mass distribution, the horizon angular velocity, the ergo-region and some basic properties of geodesic motion. For sufficiently small values of the Chern–Simons coupling our results match those previously obtained using a perturbative approach.Delsate, TerenceTue, 23 Oct 2018 03:32:54 GMThttps://repo.scoap3.org/record/28720urn:ISSN:0370-2693Elsevier2018-12-10An analytic effective model for hairy black holes
https://repo.scoap3.org/record/25444
Hairy black holes (BHs) have macroscopic degrees of freedom which are not associated with a Gauss law. As such, these degrees of freedom are not manifest as quasi-local quantities computed at the horizon. This suggests conceiving hairy BHs as an interacting system with two components: a “bald” horizon coupled to a “hairy” environment. Based on this idea we suggest an effective model for hairy BHs – typically described by numerical solutions – that allows computing analytically thermodynamic and other quantities of the hairy BH in terms of a fiducial bald BH. The effective model is universal in the sense that it is only sensitive to the fiducial BH, but not to the details of the hairy BH. Consequently, it is only valid in the vicinity of the fiducial BH limit. We discuss, quantitatively, the accuracy of the effective model for asymptotically flat BHs with synchronised hair, both in D=4 (including self-interactions) and D=5 spacetime dimensions. We also discuss the applicability of the model to synchronised BHs in D=5 asymptotically AdS and static D=4 coloured BHs, exhibiting its limitations.Brihaye, YvesThu, 10 May 2018 23:35:47 GMThttps://repo.scoap3.org/record/25444urn:ISSN:0370-2693Elsevier2018-06-26Effective stability against superradiance of Kerr black holes with synchronised hair
https://repo.scoap3.org/record/25271
Kerr black holes with synchronised hair [1,2] are a counter example to the no hair conjecture, in General Relativity minimally coupled to simple matter fields (with mass μ ) obeying all energy conditions. Since these solutions have, like Kerr, an ergoregion it has been a lingering possibility that they are afflicted by the superradiant instability, the same process that leads to their dynamical formation from Kerr. A recent breakthrough [3] confirmed this instability and computed the corresponding timescales for a sample of solutions. We discuss how these results and other observations support two conclusions: 1) starting from the Kerr limit, the increase of hair for fixed coupling μM (where M is the BH mass) increases the timescale of the instability; 2) there are hairy solutions for which this timescale, for astrophysical black hole masses, is larger than the age of the Universe. The latter conclusion introduces the limited, but physically relevant concept of effective stability . The former conclusion, allows us to identify an astrophysically viable domain of such effectively stable hairy black holes, occurring, conservatively, for Mμ≲0.25 . These are hairy BHs that form dynamically, from the superradiant instability of Kerr, within an astrophysical timescale, but whose own superradiant instability occurs only in a cosmological timescale.Degollado, Juan CarlosFri, 04 May 2018 09:33:22 GMThttps://repo.scoap3.org/record/25271urn:ISSN:0370-2693Elsevier2018-05-30Squashed, magnetized black holes in D = 5 minimal gauged supergravity
https://repo.scoap3.org/record/23688
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.Blázquez-Salcedo, JoseMon, 12 Feb 2018 07:08:46 GMThttps://repo.scoap3.org/record/23688urn:ISSN:1029-8479Springer/SISSA2018-02-09Probing the universality of synchronised hair around rotating black holes with Q -clouds
https://repo.scoap3.org/record/23597
Recently, various families of black holes (BHs) with synchronised hair have been constructed. These are rotating BHs surrounded, as fully non-linear solutions of the appropriate Einstein-matter model, by a non-trivial bosonic field in synchronised rotation with the BH horizon. Some families bifurcate globally from a bald BH ( e.g. the Kerr BH), whereas others bifurcate only locally from a bald BH ( e.g. the D=5 Myers–Perry BH). It would be desirable to understand how generically synchronisation allows hairy BHs to bifurcate from bald ones. However, the construction and scanning of the domain of existence of the former families of BHs can be a difficult and time consuming (numerical) task. Here, we first provide a simple perturbative argument to understand the generality of the synchronisation condition. Then, we observe that the study of Q-clouds is a generic tool to establish the existence of BHs with synchronised hair bifurcating (globally or locally) from a given bald BH without having to solve the fully non-linear coupled system of Einstein-matter equations. As examples, we apply this tool to establish the existence of synchronised hair around D=6 Myers–Perry BHs, D=5 black rings and D=4 Kerr- AdS BHs, where D is the spacetime dimension. The black rings case provides an example of BHs with synchronised hair beyond spherical horizon topology, further establishing the generality of the mechanism.Herdeiro, CarlosWed, 07 Feb 2018 17:53:28 GMThttps://repo.scoap3.org/record/23597urn:ISSN:0370-2693Elsevier2018-02-28Skyrmions, Skyrme stars and black holes with Skyrme hair in five spacetime dimension
https://repo.scoap3.org/record/22279
We consider a class of generalizations of the Skyrme model to five spacetime dimensions ( d = 5), which is defined in terms of an O (5) sigma model. A special ansatz for the Skyrme field allows angular momentum to be present and equations of motion with a radial dependence only. Using it, we obtain: 1) everywhere regular solutions describing localised energy lumps ( Skyrmions ); 2) Self-gravitating, asymptotically flat, everywhere non-singular solitonic solutions ( Skyrme stars ), upon minimally coupling the model to Einstein’s gravity; 3) both static and spinning black holes with Skyrme hair, the latter with rotation in two orthogonal planes, with both angular momenta of equal magnitude. In the absence of gravity we present an analytic solution that satisfies a BPS-type bound and explore numerically some of the non-BPS solutions. In the presence of gravity, we contrast the solutions to this model with solutions to a complex scalar field model, namely boson stars and black holes with synchronised hair. Remarkably, even though the two models present key differences, and in particular the Skyrme model allows static hairy black holes, when introducing rotation, the synchronisation condition becomes mandatory, providing further evidence for its generality in obtaining rotating hairy black holes.Brihaye, YvesTue, 14 Nov 2017 10:51:06 GMThttps://repo.scoap3.org/record/22279urn:ISSN:1029-8479Springer/SISSA2017-11-08Asymptotically flat scalar, Dirac and Proca stars: Discrete vs. continuous families of solutions
https://repo.scoap3.org/record/21514
The existence of localized, approximately stationary, lumps of the classical gravitational and electromagnetic field – geons – was conjectured more than half a century ago. If one insists on exact stationarity, topologically trivial configurations in electro-vacuum are ruled out by no-go theorems for solitons. But stationary, asymptotically flat geons found a realization in scalar-vacuum, where everywhere non-singular, localized field lumps exist, known as (scalar) boson stars . Similar geons have subsequently been found in Einstein–Dirac theory and, more recently, in Einstein–Proca theory. We identify the common conditions that allow these solutions, which may also exist for other spin fields. Moreover, we present a comparison of spherically symmetric geons for the spin 0,1/2 and 1, emphasizing the mathematical similarities and clarifying the physical differences, particularly between the bosonic and fermionic cases. We clarify that for the fermionic case, Pauli's exclusion principle prevents a continuous family of solutions for a fixed field mass; rather only a discrete set exists, in contrast with the bosonic case.Herdeiro, Carlos A.R.Fri, 15 Sep 2017 14:24:34 GMThttps://repo.scoap3.org/record/21514urn:ISSN:0370-2693Elsevier2017-09-26Reissner–Nordström black holes with non-Abelian hair
https://repo.scoap3.org/record/20520
We consider d⩾4 Einstein–(extended-)Yang–Mills theory, where the gauge sector is augmented by higher order terms. Linearising the (extended) Yang–Mills equations on the background of the electric Reissner–Nordström (RN) black hole, we show the existence of normalisable zero modes, dubbed non-Abelian magnetic stationary clouds . The non-linear realisation of these clouds bifurcates the RN family into a branch of static, spherically symmetric, electrically charged and asymptotically flat black holes with non-Abelian hair. Generically, the hairy black holes are thermodynamically preferred over the RN solution, which, in this model, becomes unstable against the formation of non-Abelian hair, for sufficiently large values of the electric charge.Herdeiro, CarlosSun, 18 Jun 2017 17:33:10 GMThttps://repo.scoap3.org/record/20520urn:ISSN:0370-2693Elsevier2017-08-15AdS 5 magnetized solutions in minimal gauged supergravity
https://repo.scoap3.org/record/20035
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.Blázquez-Salcedo, Jose LuisThu, 11 May 2017 00:08:12 GMThttps://repo.scoap3.org/record/20035urn:ISSN:0370-2693Elsevier2017-06-21Shadows of Einstein–dilaton–Gauss–Bonnet black holes
https://repo.scoap3.org/record/19342
We study the shadows of the fully non-linear, asymptotically flat Einstein–dilaton–Gauss–Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr BHs, i.e. with the same total mass and angular momentum under similar observation conditions. In order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. Therefore, generically, EdGB BHs cannot be excluded by (near future) shadow observations alone. On the theoretical side, we find no clear signature of some exotic features of EdGB BHs on the corresponding shadows, such as the regions of negative (Komar, say) energy density outside the horizon. We speculate that this is due to the fact that the Komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the ADM mass, and consequently the corresponding shadows are smaller than those of comparable Kerr BHs. The analysis herein provides a clear example that it is the light ring impact parameter, rather than its “size”, that determines a BH shadow.Cunha, Pedro V.P.Wed, 15 Mar 2017 21:27:42 GMThttps://repo.scoap3.org/record/19342urn:ISSN:0370-2693Elsevier2017-03-20Remarks on the Taub-NUT solution in Chern–Simons modified gravity
https://repo.scoap3.org/record/18153
We discuss the generalization of the NUT spacetime in General Relativity (GR) within the framework of the (dynamical) Einstein–Chern–Simons (ECS) theory with a massless scalar field. These configurations approach asymptotically the NUT spacetime and are characterized by the ‘electric’ and ‘magnetic’ mass parameters and a scalar ‘charge’. The solutions are found both analytically and numerically. The analytical approach is perturbative around the Einstein gravity background. Our results indicate that the ECS configurations share all basic properties of the NUT spacetime in GR. However, when considering the solutions inside the event horizon, we find that in contrast to the GR case, the spacetime curvature grows (apparently) without bound.Brihaye, YvesThu, 01 Dec 2016 16:41:28 GMThttps://repo.scoap3.org/record/18153urn:ISSN:0370-2693Elsevier2016-12-07Kerr–Newman black holes with scalar hair
https://repo.scoap3.org/record/16874
We construct electrically charged Kerr black holes (BHs) with scalar hair. Firstly, we take an uncharged scalar field, interacting with the electromagnetic field only indirectly, via the background metric. The corresponding family of solutions, dubbed Kerr–Newman BHs with ungauged scalar hair, reduces to (a sub-family of) Kerr–Newman BHs in the limit of vanishing scalar hair and to uncharged rotating boson stars in the limit of vanishing horizon. It adds one extra parameter to the uncharged solutions: the total electric charge. This leading electromagnetic multipole moment is unaffected by the scalar hair and can be computed by using Gauss's law on any closed 2-surface surrounding (a spatial section of) the event horizon. By contrast, the first sub-leading electromagnetic multipole – the magnetic dipole moment –, gets suppressed by the scalar hair, such that the gyromagnetic ratio is always smaller than the Kerr–Newman value ( g=2 ). Secondly, we consider a gauged scalar field and obtain a family of Kerr–Newman BHs with gauged scalar hair. The electrically charged scalar field now stores a part of the total electric charge, which can only be computed by applying Gauss' law at spatial infinity and introduces a new solitonic limit – electrically charged rotating boson stars. In both cases, we analyze some physical properties of the solutions.Delgado, Jorge F.M.Sat, 20 Aug 2016 15:57:48 GMThttps://repo.scoap3.org/record/16874urn:ISSN:0370-2693Elsevier2017-10-05Inside black holes with synchronized hair
https://repo.scoap3.org/record/16349
Recently, various examples of asymptotically flat, rotating black holes (BHs) with synchronized hair have been explicitly constructed, including Kerr BHs with scalar or Proca hair, and Myers–Perry BHs with scalar hair and a mass gap, showing there is a general mechanism at work. All these solutions have been found numerically, integrating the fully non-linear field equations of motion from the event horizon outwards. Here, we address the spacetime geometry of these solutions inside the event horizon. Firstly, we provide arguments, within linear theory, that there is no regular inner horizon for these solutions. Then, we address this question fully non-linearly, using as a tractable model five dimensional, equal spinning, Myers–Perry hairy BHs. We find that, for non-extremal solutions: (1) the inside spacetime geometry in the vicinity of the event horizon is smooth and the equations of motion can be integrated inwards; (2) before an inner horizon is reached, the spacetime curvature grows (apparently) without bound. In all cases, our results suggest the absence of a smooth Cauchy horizon, beyond which the metric can be extended, for hairy BHs with synchronized hair.Brihaye, YvesFri, 08 Jul 2016 15:53:59 GMThttps://repo.scoap3.org/record/16349urn:ISSN:0370-2693Elsevier2017-10-23Einstein–Maxwell–Anti-de-Sitter spinning solitons
https://repo.scoap3.org/record/15087
Electrostatics on global Anti-de-Sitter ( AdS ) spacetime is sharply different from that on global Minkowski spacetime. It admits a multipolar expansion with everywhere regular, finite energy solutions, for every multipole moment except the monopole [1] . A similar statement holds for global AdS magnetostatics. We show that everywhere regular, finite energy, electric plus magnetic fields exist on AdS in three distinct classes: ( I ) with non-vanishing total angular momentum J ; ( II ) with vanishing J but non-zero angular momentum density , Tφt ; ( III ) with vanishing J and Tφt . Considering backreaction, these configurations remain everywhere smooth and finite energy, and we find, for example, Einstein–Maxwell– AdS solitons that are globally – Type I – or locally (but not globally) – Type II – spinning. This backreaction is considered first perturbatively, using analytical methods and then non-perturbatively, by constructing numerical solutions of the fully non-linear Einstein–Maxwell– AdS system. The variation of the energy and total angular momentum with the boundary data is explicitly exhibited for one example of a spinning soliton.Herdeiro, CarlosWed, 06 Apr 2016 14:55:09 GMThttps://repo.scoap3.org/record/15087urn:ISSN:0370-2693Elsevier2017-03-20Proca stars: Gravitating Bose–Einstein condensates of massive spin 1 particles
https://repo.scoap3.org/record/12805
We establish that massive complex Abelian vector fields (mass μ ) can form gravitating solitons, when minimally coupled to Einstein's gravity. Such Proca stars (PSs) have a stationary, everywhere regular and asymptotically flat geometry. The Proca field, however, possesses a harmonic time dependence (frequency w ), realizing Wheeler's concept of geons for an Abelian spin 1 field. We obtain PSs with both a spherically symmetric (static) and an axially symmetric (stationary) line element. The latter form a countable number of families labelled by an integer m∈Z+ . PSs, like (scalar) boson stars, carry a conserved Noether charge, and are akin to the latter in many ways. In particular, both types of stars exist for a limited range of frequencies and there is a maximal ADM mass, Mmax , attained for an intermediate frequency. For spherically symmetric PSs (rotating PSs with m=1,2,3 ), Mmax≃1.058MPl2/μ ( Mmax≃1.568,2.337,3.247MPl2/μ ), slightly larger values than those for (mini-)boson stars. We establish perturbative stability for a subset of solutions in the spherical case and anticipate a similar conclusion for fundamental modes in the rotating case. The discovery of PSs opens many avenues of research, reconsidering five decades of work on (scalar) boson stars, in particular as possible dark matter candidates.Brito, RichardThu, 26 Nov 2015 02:03:44 GMThttps://repo.scoap3.org/record/12805urn:ISSN:0370-2693Elsevier2017-03-23Anti-de-Sitter regular electric multipoles: Towards Einstein–Maxwell-AdS solitons
https://repo.scoap3.org/record/11537
We discuss electrostatics in Anti-de-Sitter ( AdS ) spacetime, in global coordinates. We observe that the multipolar expansion has two crucial differences to that in Minkowski spacetime. First, there are everywhere regular solutions, with finite energy, for every multipole moment except for the monopole. Second, all multipole moments decay with the same inverse power of the areal radius, 1/r , as spatial infinity is approached. The first observation suggests there may be regular, self-gravitating, Einstein–Maxwell solitons in AdS spacetime. The second observation, renders a Lichnerowicz-type no-soliton theorem inapplicable. Consequently, we suggest Einstein–Maxwell solitons exist in AdS , and we support this claim by computing the first order metric perturbations sourced by test electric field multipoles, which are obtained analytically in closed form.Herdeiro, CarlosThu, 27 Aug 2015 10:57:05 GMThttps://repo.scoap3.org/record/11537urn:ISSN:0370-2693Elsevier2017-04-26Myers–Perry black holes with scalar hair and a mass gap: Unequal spins
https://repo.scoap3.org/record/10857
We construct rotating boson stars and Myers–Perry black holes with scalar hair (MPBHsSH) as fully non-linear solutions of five dimensional Einstein gravity minimally coupled to a complex, massive scalar field. The MPBHsSH are, in general, regular on and outside the horizon, asymptotically flat, and possess angular momentum in a single rotation plane. They are supported by rotation and have no static limit. Such hairy BHs may be thought of as bound states of boson stars and singly spinning, vacuum MPBHs and inherit properties of both these building blocks. When the horizon area shrinks to zero, the solutions reduce to (in a single plane) rotating boson stars; but the extremal limit also yields a zero area horizon, as for singly spinning MPBHs. Similarly to the case of equal angular momenta, and in contrast to Kerr black holes with scalar hair, singly spinning MPBHsSH are disconnected from the vacuum black holes, due to a mass gap. We observe that for the general case, with two unequal angular momenta, the equilibrium condition for the existence of MPBHsSH is w=m1Ω1+m2Ω2 , where Ωi are the horizon angular velocities in the two independent rotation planes and w,mi , i=1,2 , are the scalar field's frequency and azimuthal harmonic indices.Herdeiro, CarlosFri, 26 Jun 2015 14:32:26 GMThttps://repo.scoap3.org/record/10857urn:ISSN:0370-2693Elsevier2016-02-12Thermodynamic properties of asymptotically anti-de Sitter black holes in d = 4 Einstein–Yang–Mills theory
https://repo.scoap3.org/record/10533
We investigate the thermodynamics of spherically symmetric black hole solutions in a four-dimensional Einstein–Yang–Mills-SU(2) theory with a negative cosmological constant. Special attention is paid to configurations with a unit magnetic charge. We find that a set of Reissner–Nordström–Anti-de Sitter black holes can become unstable to forming non-Abelian hair. However, the hairy black holes are never thermodynamically favoured over the full set of abelian monopole solutions. The thermodynamics of the generic configurations possessing a noninteger magnetic charge is also discussed.Kichakova, OlgaMon, 01 Jun 2015 14:48:36 GMThttps://repo.scoap3.org/record/10533urn:ISSN:0370-2693Elsevier2016-05-28Charged isotropic non-Abelian dyonic black branes
https://repo.scoap3.org/record/9950
We construct black holes with a Ricci-flat horizon in Einstein–Yang–Mills theory with a negative cosmological constant, which approach asymptotically an AdS d spacetime background (with d≥4 ). These solutions are isotropic, i.e. all space directions in a hypersurface of constant radial and time coordinates are equivalent, and possess both electric and magnetic fields. We find that the basic properties of the non-Abelian solutions are similar to those of the dyonic isotropic branes in Einstein–Maxwell theory (which, however, exist in even spacetime dimensions only). These black branes possess a nonzero magnetic field strength on the flat boundary metric, which leads to a divergent mass of these solutions, as defined in the usual way. However, a different picture is found for odd spacetime dimensions, where a non-Abelian Chern–Simons term can be incorporated in the action. This allows for black brane solutions with a magnetic field which vanishes asymptotically.Brihaye, YvesMon, 20 Apr 2015 14:51:10 GMThttps://repo.scoap3.org/record/9950urn:ISSN:0370-2693Elsevier2015-05-18Black ringoids: spinning balanced black objects in d ≥ 5 dimensions — the codimension-two case
https://repo.scoap3.org/record/8895
We propose a general framework for the study of asymptotically flat black objects with k + 1 equal magnitude angular momenta in d ≥ 5 spacetime dimensions (with 0 ≤ k ≤ d − 5 2 $$ 0\le k\le \left[\frac{d-5}{2}\right] $$ ). In this approach, the dependence on all angular coordinates but one is factorized, which leads to a codimension-two problem. This framework can describe black holes with spherical horizon topology, the simplest solutions corresponding to a class of Myers-Perry black holes. A different set of solutions describes balanced black objects with S n +1 × S 2 k +1 horizon topology. The simplest members of this family are the black rings ( k = 0). The solutions with k > 0 are dubbed black ringoids . Based on the nonperturbative numerical results found for several values of ( n, k ), we propose a general picture for the properties and the phase diagram of these solutions and the associated black holes with spherical horizon topology: n = 1 black ringoids repeat the k = 0 pattern of black rings and Myers-Perry black holes in 5 dimensions, whereas n > 1 black ringoids follow the pattern of higher dimensional black rings associated with ‘pinched’ black holes and Myers-Perry black holes.Kleihaus, BurkhardThu, 22 Jan 2015 10:37:59 GMThttps://repo.scoap3.org/record/8895urn:ISSN:1029-8479Springer/SISSA2015-01-21