scholarly journals Spinning boson stars and hairy black holes with nonminimal coupling

2018 ◽  
Vol 27 (11) ◽  
pp. 1843009 ◽  
Author(s):  
Carlos A. R. Herdeiro ◽  
Eugen Radu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Coupling Parameter ◽  
Nonminimal Coupling ◽  
Boson Stars ◽  
Hairy Black Holes ◽  
Black Hole Solutions ◽  
Hairy Black Hole ◽  
Coupled Theory

We obtain spinning boson star solutions and hairy black holes with synchronized hair in the Einstein–Klein–Gordon model, wherein the scalar field is massive, complex and with a nonminimal coupling to the Ricci scalar. The existence of these hairy black holes in this model provides yet another manifestation of the universality of the synchronization mechanism to endow spinning black holes with hair. We study the variation of the physical properties of the boson stars and hairy black holes with the coupling parameter between the scalar field and the curvature, showing that they are, qualitatively, identical to those in the minimally coupled case. By discussing the conformal transformation to the Einstein frame, we argue that the solutions herein provide new rotating boson star and hairy black hole solutions in the minimally coupled theory, with a particular potential, and that no spherically symmetric hairy black hole solutions exist in the nonminimally coupled theory, under a condition of conformal regularity.

scholarly journals New non-extremal and BPS hairy black holes in gauged $$ \mathcal{N} $$ = 2 and $$ \mathcal{N} $$ = 8 supergravity

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Andres Anabalon ◽  
Dumitru Astefanesei ◽  
Antonio Gallerati ◽  
Mario Trigiante
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Boundary Conditions ◽  
Charged Black Hole ◽  
Dual Theory ◽  
Real Numbers ◽  
Hairy Black Holes ◽  
Interpolation Parameter ◽  
Black Hole Solutions ◽  
Extremal Black Holes

Abstract In this article we study a family of four-dimensional, $$ \mathcal{N} $$ N = 2 supergravity theories that interpolates between all the single dilaton truncations of the SO(8) gauged $$ \mathcal{N} $$ N = 8 supergravity. In this infinitely many theories characterized by two real numbers — the interpolation parameter and the dyonic “angle” of the gauging — we construct non-extremal electrically or magnetically charged black hole solutions and their supersymmetric limits. All the supersymmetric black holes have non-singular horizons with spherical, hyperbolic or planar topology. Some of these supersymmetric and non-extremal black holes are new examples in the $$ \mathcal{N} $$ N = 8 theory that do not belong to the STU model. We compute the asymptotic charges, thermodynamics and boundary conditions of these black holes and show that all of them, except one, introduce a triple trace deformation in the dual theory.

scholarly journals Logarithmic corrections of charged hairy black holes in (2 + 1) dimensions

2014 ◽  
Vol 92 (12) ◽  
pp. 1638-1642 ◽  
Author(s):  
J. Sadeghi ◽  
B. Pourhassan ◽  
F. Rahimi
Keyword(s):  
Field Theory ◽  
Black Holes ◽  
Black Hole ◽  
Conformal Field Theory ◽  
Scalar Field ◽  
Thermodynamic Properties ◽  
Conformal Field ◽  
Logarithmic Corrections ◽  
Hairy Black Holes ◽  
Metric Function

We consider a charged black hole with a scalar field that is coupled to gravity in (2 + 1)-dimensions. We compute the logarithmic corrections to the corresponding system using two approaches. In the first method we take advantage of thermodynamic properties. In the second method we use the metric function that is suggested by conformal field theory. Finally, we compare the results of the two approaches.

scholarly journals ECO-spotting: looking for extremely compact objects with bosonic fields

2021 ◽  
Author(s):  
Vitor Cardoso ◽  
Caio F. B. Macedo ◽  
Kei-ichi Maeda ◽  
Hirotada Okawa
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Compact Objects ◽  
Spherically Symmetric ◽  
Initial Value ◽  
Flat Spacetime ◽  
The Universe ◽  
Well Posed ◽  
Black Hole Solutions ◽  
Hairy Black Hole

Abstract Black holes are thought to describe the geometry of massive, dark compact objects in the universe. To further support and quantify this long-held belief requires knowledge of possible, if exotic alternatives. Here, we wish to understand how compact can self-gravitating solutions be. We discuss theories with a well-posed initial value problem, consisting in either a single self-interacting scalar, vector or both. We focus on spherically symmetric solutions, investigating the influence of self-interacting potentials into the compactness of the solutions, in particular those that allow for flat-spacetime solutions. We are able to connect such stars to hairy black hole solutions, which emerge as a zero-mass black hole. We show that such stars can have light rings, but their compactness is never parametrically close to that of black holes. The challenge of finding black hole mimickers to investigate full numerical-relativity binary setups remains open.

scholarly journals A new spin on black hole hair

2014 ◽  
Vol 23 (12) ◽  
pp. 1442014 ◽  
Author(s):  
Carlos A. R. Herdeiro ◽  
Eugen Radu
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Massive Scalar ◽  
Massive Scalar Field ◽  
Hairy Black Holes ◽  
Scalar Hair

We show that scalar hair can be added to rotating, vacuum black holes (BHs) of general relativity. These hairy black holes (HBHs) clarify a lingering question concerning gravitational solitons: Whether a BH can be added at the centre of a boson star (BS), as it typically can for other solitons. We argue that it can, but only if it is spinning. The existence of such HBHs is related to the Kerr superradiant instability triggered by a massive scalar field. This connection leads to the following conjecture: a (hairless) BH, which is afflicted by the superradiant instability of a given field, must allow hairy generalizations with that field.

BLACK HOLES HAVE LONG HAIR

2012 ◽  
Vol 21 (11) ◽  
pp. 1242003 ◽  
Author(s):  
SHAHAR HOD
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Angular Momentum ◽  
Spatial Behavior ◽  
Black Hole Horizon ◽  
Hairy Black Holes ◽  
Matter Fields ◽  
Circular Geodesic ◽  
Hairy Black Hole

The influential "no-hair" conjecture suggests that black holes may be characterized by only three conserved parameters: mass, charge and angular momentum. However, counterexamples in which the conjecture fails are well-known in the literature. In this essay we study such Einstein-matter theories in which hairy black-hole configurations have been discovered. In particular, we analyze the spatial behavior of the matter fields which reside outside the black-hole horizon. We prove a theorem which reveals the central role played by the null circular geodesic (the "photonsphere") of such hairy black holes. According to this theorem, the asymptotic decline of the hair outside the horizon cannot start before the black-hole photonsphere is crossed. We therefore conclude that hairy black holes must have long hair which extends beyond the photonsphere.

scholarly journals Scalarized black holes

2021 ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Burkhard Kleihaus ◽  
Jutta Kunz
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Alternative Theories Of Gravity ◽  
Gravitational Action ◽  
Theories Of Gravity ◽  
Bonnet Term ◽  
Alternative Theories ◽  
Black Hole Solutions

AbstractBlack holes represent outstanding astrophysical laboratories to test the strong gravity regime, since alternative theories of gravity may predict black hole solutions whose properties may differ distinctly from those of general relativity. When higher curvature terms are included in the gravitational action as, for instance, in the form of the Gauss–Bonnet term coupled to a scalar field, scalarized black holes result. Here we discuss several types of scalarized black holes and some of their properties.

scholarly journals Gauss–Bonnet black holes supporting massive scalar field configurations: the large-mass regime

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Coupling Parameter ◽  
Analytical Formula ◽  
Analytical Techniques ◽  
Scalar Fields ◽  
Large Field ◽  
Massive Scalar Field ◽  
Black Hole Spacetimes

AbstractIt has recently been demonstrated that black holes with spatially regular horizons can support external scalar fields (scalar hairy configurations) which are non-minimally coupled to the Gauss–Bonnet invariant of the curved spacetime. The composed black-hole-scalar-field system is characterized by a critical existence line $$\alpha =\alpha (\mu r_{\text {H}})$$α=α(μrH) which, for a given mass of the supported scalar field, marks the threshold for the onset of the spontaneous scalarization phenomenon [here $$\{\alpha ,\mu ,r_{\text {H}}\}$${α,μ,rH} are respectively the dimensionless non-minimal coupling parameter of the field theory, the proper mass of the scalar field, and the horizon radius of the central supporting black hole]. In the present paper we use analytical techniques in order to explore the physical and mathematical properties of the marginally-stable composed black-hole-linearized-scalar-field configurations in the eikonal regime $$\mu r_{\text {H}}\gg 1$$μrH≫1 of large field masses. In particular, we derive a remarkably compact analytical formula for the critical existence-line $$\alpha =\alpha (\mu r_{\text {H}})$$α=α(μrH) of the system which separates bare Schwarzschild black-hole spacetimes from composed hairy (scalarized) black-hole-field configurations.

scholarly journals Phase diagram of the charged black hole bomb system

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Alex Davey ◽  
Oscar J. C. Dias ◽  
Paul Rodgers
Keyword(s):  
Phase Diagram ◽  
Black Holes ◽  
Black Hole ◽  
Charged Black Hole ◽  
Energy Conditions ◽  
Boson Stars ◽  
Horizon Radius ◽  
Hairy Black Holes ◽  
Surface Tensor ◽  
Quasilocal Mass

Abstract We find the phase diagram of solutions of the charged black hole bomb system. In particular, we find the static hairy black holes of Einstein-Maxwell-Scalar theory confined in a Minkowski box. We impose boundary conditions such that the scalar field vanishes at and outside a cavity of constant radius. These hairy black holes are asymptotically flat with a scalar condensate floating above the horizon. We identify four critical scalar charges which mark significant changes in the qualitative features of the phase diagram. When they coexist, hairy black holes always have higher entropy than the Reissner-Nordström black hole with the same quasilocal mass and charge. So hairy black holes are natural candidates for the endpoint of the superradiant/near-horizon instabilities of the black hole bomb system. We also relate hairy black holes to the boson stars of the theory. When it has a zero horizon radius limit, the hairy black hole family terminates on the boson star family. Finally, we find the Israel surface tensor of the box required to confine the scalar condensate and that it can obey suitable energy conditions.

scholarly journals Quasinormal modes of hot, cold and bald Einstein–Maxwell-scalar black holes

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Carlos A. R. Herdeiro ◽  
Sarah Kahlen ◽  
Jutta Kunz ◽  
Alexandre M. Pombo ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Unstable Mode ◽  
Quasinormal Modes ◽  
Coupling Function ◽  
Quartic Coupling ◽  
Linear Mode ◽  
Mode Stability ◽  
Black Hole Solutions

AbstractEinstein–Maxwell-scalar models allow for different classes of black hole solutions, depending on the non-minimal coupling function $$f(\phi )$$ f ( ϕ ) employed, between the scalar field and the Maxwell invariant. Here, we address the linear mode stability of the black hole solutions obtained recently for a quartic coupling function, $$f(\phi )=1+\alpha \phi ^4$$ f ( ϕ ) = 1 + α ϕ 4 (Blázquez-Salcedo et al. in Phys. Lett. B 806:135493, 2020). Besides the bald Reissner–Nordström solutions, this coupling allows for two branches of scalarized black holes, termed cold and hot, respectively. For these three branches of black holes we calculate the spectrum of quasinormal modes. It consists of polar scalar-led modes, polar and axial electromagnetic-led modes, and polar and axial gravitational-led modes. We demonstrate that the only unstable mode present is the radial scalar-led mode of the cold branch. Consequently, the bald Reissner–Nordström branch and the hot scalarized branch are both mode-stable. The non-trivial scalar field in the scalarized background solutions leads to the breaking of the degeneracy between axial and polar modes present for Reissner–Nordström solutions. This isospectrality is only slightly broken on the cold branch, but it is strongly broken on the hot branch.

scholarly journals Scalar modes, spontaneous scalarization and circular null-geodesics of black holes in scalar-Gauss–Bonnet gravity

2020 ◽  
Vol 29 (11) ◽  
pp. 2041006 ◽  
Author(s):  
Caio F. B. Macedo
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Quasinormal Modes ◽  
Mode Analysis ◽  
Bonnet Gravity ◽  
Black Hole Binaries ◽  
The Impact ◽  
Black Hole Solutions

In general relativity, astrophysical black holes (BHs) are simple objects, described by just their mass and spin. These simple solutions are not exclusive to general relativity, as they also appear in theories that allow for an extra scalar degree of freedom. Recently, it was shown that some theories which couple a scalar field with the Gauss–Bonnet invariant can have the same classic black hole solutions from general relativity as well as hairy BHs. These scalarized solutions can be stable, having an additional “charge” term that has an impact on the gravitational-wave emission by black hole binaries. In this paper, we overview black hole solutions in scalar-Gauss–Bonnet gravity, considering self-interacting terms for the scalar field. We present the mode analysis for the monopolar and dipolar perturbations around the Schwarzschild black hole in scalar-Gauss–Bonnet, showing the transition between stable and unstable solutions. We also present the time-evolution of scalar Gaussian wave packets, analyzing the impact of the scalar-Gauss–Bonnet term in their evolution. We then present some scalarized solutions, showing that nonlinear coupling functions and self-interacting terms can stabilize them. Finally, we compute the light-ring frequency and the Lyapunov exponent, which possibly estimate the black hole quasinormal modes in the eikonal limit.

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