240 citations · 319 across the 22 of their papers we have counts for
22 papers
Perturbations and stability of black holes with static scalar hair in general GLPV theories
Petarpa Boonserm, Antonio De Felice, Ratchaphat Nakarachinda +2
We derive the background equations and complete odd- and even-parity quadratic actions for static, spherically symmetric black holes with radial scalar hair in general quartic-quin…
Static regular black holes in Horndeski theories: analytic no-go and nonanalytic obstructions
Antonio De Felice, Shinji Tsujikawa
Regular black holes in Horndeski theories must have stable horizons and regular centers. We study static, spherically symmetric, asymptotically flat configurations with a time-inde…
A solid unification of the dark sector
Jose Beltrán Jiménez, María Pérez Garrote, Florencia A. Teppa Pannia +1
We construct a unified description of dark matter and dark energy in terms of a single dark component that behaves as a pressureless fluid in the early Universe and undergoes a tra…
Inspiral gravitational waveforms from charged compact binaries with scalar hair
Antonio De Felice, Shinji Tsujikawa
We investigate gravitational waveforms from compact binary systems in Einstein-scalar-Maxwell (ESM) theories, where a scalar field couples to a gauge field through…
Revisiting observational constraints on coupled exponential quintessence with energy and momentum transfers: degeneracy with massive neutrinos
Jose Beltrán Jiménez, Kiyotomo Ichiki, Xiaolin Liu +2
We investigate the impact of massive neutrinos on cosmological models in which dark energy, described by a quintessence scalar field with an exponential potential, interacts wi…
Light rings, gravitational lensing, and ISCOs of exotic compact objects in Einstein-scalar-Maxwell theories
Antonio De Felice, Shinji Tsujikawa
In Einstein-scalar-Maxwell theories with a coupling between the scalar field and the electromagnetic field strength of the form , we investigate the existence of ex…
Higgs-Portal Stueckelberg Dark Matter
Antonio De Felice, Takehiro Ogura, Shinji Tsujikawa +1
We study dark photon dark matter associated with a dark gauge symmetry. To evade laboratory and cosmological constraints on kinetic mixing with the Standard Model $U(1…
Exotic compact objects in Einstein-scalar-Maxwell theories
Antonio De Felice, Shinji Tsujikawa
In k-essence theories within general relativity, where the matter Lagrangian depends on a real scalar field and its kinetic term , static and spherically symmetric compact o…
Vector Horndeski black holes in nonlinear electrodynamics
Che-Yu Chen, Antonio De Felice, Shinji Tsujikawa +1
On a spherically symmetric and static background, we study the existence of linearly stable black hole (BH) solutions in nonlinear electrodynamics (NED) with a Horndeski vector-ten…
Instability of regular planar black holes in four dimensions arising from an infinite sum of curvature corrections
Antonio De Felice, Shinji Tsujikawa
In four-dimensional scalar-tensor theories derived via dimensional regularization with a conformal rescaling of the metric, we study the stability of planar black holes (BHs) whose…
Greybody factors of charged black holes with axion hair
Ratchaphat Nakarachinda, Petarpa Boonserm, Antonio De Felice +2
We study the greybody factor of charged hairy black holes (BHs) that arise due to the presence of an axion coupled to the electromagnetic field. Specifically, we consider spin-0 an…
Strong coupling and instabilities in singularity-free inflation from an infinite sum of curvature corrections
Shinji Tsujikawa
Four-dimensional gravitational theories derived from an infinite sum of Lovelock curvature invariants, combined with a conformal rescaling of the metric, are equivalent to a subcla…
Nonsingular black holes and spherically symmetric objects in nonlinear electrodynamics with a scalar field
Antonio De Felice, Shinji Tsujikawa
In general relativity with vector and scalar fields given by the Lagrangian , where is a Maxwell term and is a kinetic term of the scalar field , we stu…
Instability of nonsingular black holes in nonlinear electrodynamics
Antonio De Felice, Shinji Tsujikawa
We show that nonsingular black holes realized in nonlinear electrodynamics are always prone to Laplacian instability around the center because of a negative squared sound speed in…
Scrutinizing black hole stability in cubic vector Galileon theories
Antonio De Felice, Ryotaro Kase, Shinji Tsujikawa
In a subclass of generalized Proca theories where a cubic vector Galileon term breaks the gauge invariance, it is known that there are static and spherically symmetric black…
Even- and odd-parity stabilities of black holes in Einstein-Aether gravity
Antonio De Felice, Shinji Mukohyama, Shinji Tsujikawa +2
In Einstein-Aether theories with a timelike unit vector field, we study the linear stability of static and spherically symmetric black holes against both even- and odd-parity pertu…
Revisiting linear stability of black hole odd-parity perturbations in Einstein-Aether gravity
Shinji Mukohyama, Shinji Tsujikawa, Anzhong Wang
In Einstein-Aether gravity, we revisit the issue of linear stabilities of black holes against odd-parity perturbations on a static and spherically symmetric background. In this the…
Linear stability of vector Horndeski black holes
Che-Yu Chen, Antonio De Felice, Shinji Tsujikawa
Horndeski's vector-tensor (HVT) gravity is described by a Lagrangian in which the field strength of a vector field interacts with a dou…
Angular and radial stabilities of spontaneously scalarized black holes in the presence of scalar-Gauss-Bonnet couplings
Masato Minamitsuji, Shinji Mukohyama, Shinji Tsujikawa
We study the linear stability of spontaneously scalarized black holes (BHs) induced by a scalar field coupled to a Gauss-Bonnet (GB) invariant . For the scalar-GB…
Gravitational-wave constraints on scalar-tensor gravity from a neutron star and black-hole binary GW200115
Hiroki Takeda, Shinji Tsujikawa, Atsushi Nishizawa
In nonminimally coupled theories where a scalar field is coupled to the Ricci scalar, neutron stars (NSs) can have scalar charges through an interaction with matter mediated by gra…
Conditions for the cosmological viability of the most general scalar-tensor theories and their applications to extended Galileon dark energy models
Antonio De Felice, Shinji Tsujikawa
In the Horndeski's most general scalar-tensor theories with second-order field equations, we derive the conditions for the avoidance of ghosts and Laplacian instabilities associate…
Are Kaluza-Klein modes enhanced by parametric resonance?
S. Tsujikawa
We study parametric amplification of Kaluza-Klein (KK) modes in a higher -dimensional generalized Kaluza-Klein theory, which was originally considered by Mukohyama in the narrow…