scholarly journals Wormhole solutions with NUT charge in higher curvature theories

2021 ◽  
Author(s):  
Rustam Ibadov ◽  
Burkhard Kleihaus ◽  
Jutta Kunz ◽  
Sardor Murodov
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Coupling Parameter ◽  
Singular Solutions ◽  
Source Terms ◽  
Curvature Invariant ◽  
Scalar Charge ◽  
Domain Of Existence ◽  
Chern Simons ◽  
Bonnet Term

AbstractWe present wormholes with a Newman–Unti–Tamburino (NUT) charge that arise in certain higher curvature theories, where a scalar field is coupled to a higher curvature invariant. For the invariants we employ (i) a Gauss–Bonnet term and (ii) a Chern–Simons term, which then act as source terms for the scalar field. We map out the domain of existence of wormhole solutions by varying the coupling parameter and the scalar charge for a set of fixed values of the NUT charge. The domain of existence for a given NUT charge is then delimited by the set of scalarized nutty black holes, a set of wormhole solutions with a degenerate throat and a set of singular solutions.

scholarly journals Scalarized Nutty Wormholes

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 89
Author(s):  
Rustam Ibadov ◽  
Burkhard Kleihaus ◽  
Jutta Kunz ◽  
Sardor Murodov
Keyword(s):  
Coupling Parameter ◽  
Polar Angle ◽  
Coupling Constant ◽  
Closed Timelike Curves ◽  
Scalar Charge ◽  
Domain Of Existence ◽  
Chern Simons

We construct scalarized wormholes with a NUT charge in higher curvature theories. We consider both Einstein-scalar-Gauss-Bonnet and Einstein-scalar-Chern-Simons theories, following Brihaye, Herdeiro and Radu, who recently studied spontaneously scalarised Schwarzschild-NUT solutions. By varying the coupling parameter and the scalar charge we determine the domain of existence of the scalarized nutty wormholes, and their dependence on the NUT charge. In the Gauss-Bonnet case the known set of scalarized wormholes is reached in the limit of vanishing NUT charge. In the Chern-Simons case, however, the limit is peculiar, since with vanishing NUT charge the coupling constant diverges. We focus on scalarized nutty wormholes with a single throat and study their properties. All these scalarized nutty wormholes feature a critical polar angle, beyond which closed timelike curves are present.

scholarly journals Extremal rotating black holes in Einstein–Maxwell–Chern–Simons theory: Radially excited solutions and nonuniqueness

2015 ◽  
Vol 24 (09) ◽  
pp. 1542016
Author(s):  
Jose Luis Blázquez-Salcedo
Keyword(s):  
Black Holes ◽  
Coupling Parameter ◽  
Global Solutions ◽  
Extremal Solutions ◽  
Simons Theory ◽  
Node Number ◽  
Domain Of Existence ◽  
Spherical Topology ◽  
Chern Simons ◽  
Chern Simons Theory

We study five-dimensional black holes in Einstein–Maxwell–Chern–Simons theory with free Chern–Simons (CS) coupling parameter. We consider an event horizon with spherical topology, and both angular momenta of equal magnitude. In particular, we study extremal black holes, which can be used to obtain the boundary of the domain of existence. Above a critical value of the CS coupling constant we find nonstatic extremal solutions with vanishing angular momentum. These solutions form a sequence which can be labeled by the node number of the magnetic U(1) potential or the inertial dragging. As the node number increases, their mass converges to the mass of the extremal Reissner–Nordström solution. The near-horizon geometry of the solutions of this sequence is the same. In general not all near-horizon solutions are found as global solutions, and we show nonuniqueness between extremal solutions and nonextremal ones.

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 Massive scalar field perturbation on Kerr black holes in dynamical Chern–Simons gravity

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Shao-Jun Zhang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Massive Scalar ◽  
Coupling Constant ◽  
Field Mass ◽  
Field Perturbation ◽  
Massive Scalar Field ◽  
Kerr Black Holes ◽  
Chern Simons

AbstractWe study massive scalar field perturbation on Kerr black holes in dynamical Chern–Simons gravity by performing a $$(2+1)$$ ( 2 + 1 ) -dimensional simulation. Object pictures of the wave dynamics in time domain are obtained. The tachyonic instability is found to always occur for any nonzero black hole spin and any scalar field mass as long as the coupling constant exceeds a critical value. The presence of the mass term suppresses or even quench the instability. The quantitative dependence of the onset of the tachyonic instability on the coupling constant, the scalar field mass and the black hole spin is given numerically.

scholarly journals Nutty black holes in Galileon scalar-tensor gravity

2018 ◽  
Vol 33 (32) ◽  
pp. 1850189 ◽  
Author(s):  
A. Brandelet ◽  
Y. Brihaye ◽  
T. Delsate ◽  
L. Ducobu
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Einstein Gravity ◽  
Parameter Family ◽  
Hairy Black Holes ◽  
Two Parameter ◽  
Bonnet Term

Einstein gravity supplemented by a scalar field nonminimally coupled to a Gauss–Bonnet term provides an example of model of scalar-tensor gravity where hairy black holes do exist. We consider the classical equations within a metric endowed with a NUT-charge and obtain a two-parameter family of nutty-hairy black holes. The pattern of these solutions in the exterior and the interior of their horizon is studied in some details. The influence of both — the hairs and the NUT-charge — on the lightlike and timelike geodesics is emphasized.

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 STUDY OF SYMMETRY IN F(R) THEORY OF GRAVITY

2010 ◽  
Vol 25 (31) ◽  
pp. 2667-2676 ◽  
Author(s):  
ABHIK KUMAR SANYAL
Keyword(s):  
Gravitational Field ◽  
Scalar Field ◽  
Coupling Parameter ◽  
Field Variable ◽  
Higher Order ◽  
Early Age ◽  
Curvature Invariant ◽  
Single Frame ◽  
Coupling Parameters ◽  
Conserved Current

An action in which the Ricci scalar is non-minimally coupled with a scalar field and contains higher order curvature invariant terms carries a conserved current under certain conditions that decouples geometric part from the scalar field. The conserved current relates the pair of arbitrary coupling parameters f(ϕ) and ω(ϕ) with the gravitational field variable, where ω(ϕ) is the Brans–Dicke coupling parameter. The existence of such conserved current may be helpful to sketch the cosmological evolution from its early age till date in a single frame.

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 Critical Solutions of Scalarized Black Holes

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2057
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Sarah Kahlen ◽  
Jutta Kunz
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Critical Value ◽  
Magnetic Monopoles ◽  
Space Time ◽  
Quartic Coupling ◽  
Charged Black Holes ◽  
Hairy Black Holes ◽  
Domain Of Existence ◽  
Scalar Hair

We consider charged black holes with scalar hair obtained in a class of Einstein–Maxwell– scalar models, where the scalar field is coupled to the Maxwell invariant with a quartic coupling function. Besides the Reissner–Nordström black holes, these models allow for black holes with scalar hair. Scrutinizing the domain of existence of these hairy black holes, we observe a critical behavior. A limiting configuration is encountered at a critical value of the charge, where space time splits into two parts: an inner space time with a finite scalar field and an outer extremal Reissner–Nordström space time. Such a pattern was first observed in the context of gravitating non-Abelian magnetic monopoles and their hairy black holes.

scholarly journals Spinning boson stars and Kerr black holes with scalar hair: The effect of self-interactions

2016 ◽  
Vol 25 (09) ◽  
pp. 1641014 ◽  
Author(s):  
Carlos A. R. Herdeiro ◽  
Eugen Radu ◽  
Helgi F. Rúnarsson
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Coupling Parameter ◽  
Boson Stars ◽  
General Picture ◽  
Maximal Mass ◽  
Scalar Hair ◽  
Kerr Black Holes ◽  
Physical Features

Self-interacting boson stars (BSs) have been shown to alleviate the astrophysically low maximal mass of their nonself-interacting counterparts. We report some physical features of spinning self-interacting BSs, namely their compactness, the occurrence of ergo-regions and the scalar field profiles, for a sample of values of the coupling parameter. The results agree with the general picture that these BSs are comparatively less compact than the nonself-interacting ones. We also briefly discuss the effect of scalar self-interactions on the properties of Kerr black holes with scalar hair.

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