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A bstract We propose a general framework for the study of asymptotically flat spinning dyonic extremal black holes (eBHs) in D = 4 Einstein-Maxwell-dilaton theory. Restricting to the stringy value γ = 1 of the dilaton coupling constant, we report on the existence of a one parameter family of eBHs which are free of pathologies, provided their magnetic and electric charges are equal. An understanding of this condition is found from a study of the near horizon limit of the solutions, both perturbative closed form and numerical solutions being presented.

We study extremal, rotating black holes in four-dimensional Einstein-Maxwell-axion (EMA) theory through a combined near-horizon and bulk analysis. At the level of the near-horizon extremal geometry (NHEG), using the entropy function formalism, we prove that regular rotating attractors with axionic hair exist only for configurations that are purely electrically or purely magnetically charged; regular rotating dyonic attractors are excluded by the axion equation of motion, a result that we established perturbatively and non-perturbatively within the NHEG system. On the global side, we construct families of asymptotically flat, rotating extremal EMA black holes that interpolate to the electric NHEG branch, confirming that horizon data are fixed by extremization of the entropy function and decoupled from asymptotic moduli in line with the attractor mechanism.

The asymptotically flat, electrically charged, rotating black holes (BHs) in Einstein-Maxwell-dilaton (EMd) theory are known in closed form for only two particular values of the dilaton coupling constant \\(\\): the Einstein-Maxwell coupling (\\(=0\\)), corresponding to the Kerr-Newman (KN) solution, and the Kaluza-Klein coupling (\\(=3\\)). Rotating solutions with arbitrary \\(\\) are known only in the slow-rotation or weakly charged limits. In this work, we numerically construct such EMd BHs with arbitrary \\(\\). We present an overview of the parameter space of the solutions for illustrative values of \\(\\) together with a study of their basic properties. The solutions are in general KN-like; there are however, new features. The data suggest that the spinning solutions with \\(0<<3\\) possess a zero temperature limit, which, albeit regular in terms of curvature invariants, exhibits a \\(pp\\)-singularity. A different limiting behaviour is found for \\(>3\\), in which case, moreover, we have found hints of BH non-uniqueness for the same global charges.

We study the dynamical stability of Proca-Higgs stars, in spherical symmetry. These are solutions of the Einstein-Proca-Higgs model, which features a Higgs-like field coupled to a Proca field, both of which minimally coupled to the gravitational field. The corresponding stars can be regarded as Proca stars with self-interactions, while avoiding the hyperbolicity issues of self-interacting Einstein-Proca models. We report that these configurations are stable near the Proca limit in the candidate stable branches, but exhibit instabilities in certain parts of the parameter space, even in the candidate stable branches, regaining their stability for very strong self-interactions. This shows that for these models, unlike various examples of scalar boson stars, self-interactions can deteriorate, rather than improve, the dynamical robustness of bosonic stars.

We consider a Proca-Higgs model wherein a complex vector field gains mass via spontaneous symmetry breaking, by coupling to a real scalar field with a Higgs-type potential. This vector version of the scalar Friedberg-Lee-Sirlin model, can be considered as a UV completion of a complex Proca model with self-interactions. We study the flat spacetime and self-gravitating solitons of the model, that we dub Proca-Higgs balls and stars respectively, exploring the domain of solutions and describing some of their mathematical and physical properties. The stars reduce to the well-known (mini-)Proca stars in some limits. The full model evades the hyperbolicity problems of the self-interacting Proca models, offering novel possibilities for dynamical studies beyond mini-Proca stars.

In the present work, we carry out the study of scattering solitons for the anti-kink/kink and kink/anti-kink configurations. Furthermore, we can observe the same effects as those described by D. Bazeia et al.. We apply the collective coordinate approximation method to describe both scattering configurations and verify that just as happens in the polynomial models \\(^4\\) and \\(^6\\), the method has its limitations regarding the initial scattering speeds. In such a way that, for certain initial speeds, the solution of collective coordinates agrees with the fullsimulation, and for other speeds, there is a discrepancy in the solutions obtained by these two methods. We also noticed that, considering the hybrid model, the null-vector problem persists for both configurations, and when trying to fix it, a singularity is created in moduli-space as well as in \\(^4\\).

In the present paper binary configurations of identical corotating Kerr-Newman black holes separated by a massless strut are derived and studied. After solving the axis conditions and establishing the absence of magnetic charges in the solution, one gets two 4-parametric corotating binary black hole models endowed with electric charge, where each source contains equal/opposite electric charge in the first/second configuration. Since the black hole horizons are given by concise expressions in terms of physical parameters, all their thermodynamical properties satisfying the Smarr relation for the mass are also obtained. We discuss the physical limits of both models.

We study extremal, rotating black holes in four-dimensional Einstein-Maxwell-axion (EMA) theory through a combined near-horizon and bulk analysis. At the level of the near-horizon extremal geometry (NHEG), using the entropy function formalism, we prove that regular rotating attractors with axionic hair exist only for configurations that are purely electrically or purely magnetically charged; regular rotating dyonic attractors are excluded by the axion equation of motion, a result that we established perturbatively and non-perturbatively within the NHEG system. On the global side, we construct families of asymptotically flat, rotating extremal EMA black holes that interpolate to the electric NHEG branch, confirming that horizon data are fixed by extremization of the entropy function and decoupled from asymptotic moduli in line with the attractor mechanism.

The asymptotically flat, electrically charged, rotating black holes (BHs) in Einstein-Maxwell-dilaton (EMd) theory are known in closed form for only two particular values of the dilaton coupling constant \\(\\): the Einstein-Maxwell coupling (\\(=0\\)), corresponding to the Kerr-Newman (KN) solution, and the Kaluza-Klein coupling (\\(=3\\)). Rotating solutions with arbitrary \\(\\) are known only in the slow-rotation or weakly charged limits. In this work, we numerically construct such EMd BHs with arbitrary \\(\\). We present an overview of the parameter space of the solutions for illustrative values of \\(\\) together with a study of their basic properties. The solutions are in general KN-like; there are however, new features. The data suggest that the spinning solutions with \\(0<<3\\) possess a zero temperature limit, which, albeit regular in terms of curvature invariants, exhibits a \\(pp\\)-singularity. A different limiting behaviour is found for \\(>3\\), in which case, moreover, we have found hints of BH non-uniqueness for the same global charges.

We propose a general framework for the study of asymptotically flat spinning dyonic ıt extremal black holes (eBHs) in \\(D=4\\) Einstein-Maxwell-dilaton theory. Restricting to the stringy value \\(=1\\) of the dilaton coupling constant, we report on the existence of a one parameter family of eBHs which are free of pathologies, provided their magnetic and electric charges are equal. An understanding of this condition is found from a study of the near horizon limit of the solutions, both perturbative closed form and numerical solutions being presented.