404 citations · 705 across the 23 of their papers we have counts for
22 papers · 1 filter
Magnetized dynamical black holes
Jibril Ben Achour, Adolfo Cisterna, Amaro Díaz +1
We construct a novel exact solution of the Einstein-scalar-Maxwell equations describing a dynamical black hole immersed in an external, time-dependent electromagnetic field. Motiva…
Dynamical axisymmetric compact objects in General Relativity
Jibril Ben Achour, Adolfo Cisterna, Mokhtar Hassaine
The search for exact solutions describing asymptotically FLRW compact objects in General Relativity remains a challenging problem. Progress has largely been limited to the spherica…
Displacement versus velocity memory effects from a gravitational plane wave
Jibril Ben Achour, Jean-Philippe Uzan
This article demonstrates that additionally to the well-known velocity memory effect, a vacuum gravitational plane wave can also induce a displacement memory on a couple of test pa…
Quadratic perturbations of the Schwarzschild black hole: The algebraically special sector
Jibril Ben Achour, Hugo Roussille
We investigate quadratic algebraically special perturbations (ASPs) of the Schwarzschild black hole. Their dynamics are derived from the expansion up to second order in perturbatio…
Nonlinear gravitational waves in Horndeski gravity: Scalar pulse and memories
Jibril Ben Achour, Mohammad Ali Gorji, Hugo Roussille
We present and analyze a new non-perturbative radiative solution of Horndeski gravity. This exact solution is constructed by a disformal mapping of a seed solution of the shift-sym…
Disformal gravitational waves
Jibril Ben Achour, Mohammad Ali Gorji, Hugo Roussille
Contrary to conformal transformations, disformal transformations can change the principal null directions of a spacetime geometry. Thus, depending on the frame a gravitational wave…
Schrödinger symmetry of Schwarzschild-(A)dS black hole mechanics
Jibril Ben Achour, Etera R. Livine, Daniele Oriti
We show that the dynamics of Schwarzschild-(A)dS black holes admits a symmetry under the 2d Schrödinger group, whatever the sign or value of the cosmological constant. This is achi…
Schrödinger Symmetry in Gravitational Mini-Superspaces
Jibril Ben Achour, Etera R. Livine, Daniele Oriti +1
We prove that the simplest gravitational symmetry reduced models describing cosmology and black holes mechanics are invariant under the Schrödinger group. We consider the flat FRW…
Hidden symmetry of the static response of black holes: Applications to Love numbers
Jibril Ben Achour, Etera R. Livine, Shinji Mukohyama +1
We show that any static linear perturbations around Schwarzschild black holes enjoy a set of conserved charges which forms a centrally extended Schrödinger algebra sh(1) = sl$(2,\m…
Symmetries and conformal bridge in Schwarzschild-(A)dS black hole mechanics
Jibril Ben Achour, Etera R. Livine
We show that the Schwarzschild-(A)dS black hole mechanics possesses a hidden symmetry under the three-dimensional Poincaré group. This symmetry shows up after having gauge-fixed th…
Disformal map and Petrov classification in modified gravity
Jibril Ben Achour, Antonio De Felice, Mohammad Ali Gorji +2
Disformal transformation provides a map relating different scalar-tensor and vector-tensor theories and gives access to a powerful solution-generating method in modified gravity. I…
Proper time reparametrization in cosmology: Mobius symmetry and Kodama charges
Jibril Ben Achour
It has been noticed that for a large class of cosmological models, the gauge fixing of the time-reparametrization invariance does not completely fix the clock. Instead, the system…
Cosmology as a CFT
Jibril Ben Achour, Etera R. Livine
We show that the simplest FLRW cosmological system consisting in the homogeneous and isotropic massless Einstein-Scalar system enjoys a hidden conformal symmetry under the 1D confo…
Non-singular black holes and the Limiting Curvature Mechanism: A Hamiltonian perspective
Jibril Ben Achour, Frederic Lamy, Hongguang Liu +1
We revisit the non-singular black hole solution in (extended) mimetic gravity with a limiting curvature from a Hamiltonian point of view. We introduce a parameterization of the pha…
Covariance in self dual inhomogeneous models of effective quantum geometry: Spherical symmetry and Gowdy systems
Jibril Ben Achour, Suddhasattwa Brahma
When applying the techniques of Loop Quantum Gravity (LQG) to symmetry-reduced gravitational systems, one first regularizes the scalar constraint using holonomy corrections, prior…
The Thiemann Complexifier and the CVH algebra for Classical and Quantum FLRW Cosmology
Jibril Ben Achour, Etera R. Livine
In the context of Loop Quantum Gravity (LQG), we study the fate of Thiemann complexifier in homogeneous and isotropic FRW cosmology. The complexifier is the dilatation operator act…
A new look at scalar perturbations in loop quantum cosmology: (un)deformed algebra approach using self dual variables
Jibril Ben Achour, Suddhasattwa Brahma, Julien Grain +1
Scalar cosmological perturbations in loop quantum cosmology (LQC) is revisited in a covariant manner, using self dual Ashtekar variables. For real-valued Ashtekar-Barbero variables…
Spherically symmetric sector of self dual Ashtekar gravity coupled to matter: Anomaly-free algebra of constraints with holonomy corrections
Jibril Ben Achour, Suddhasattwa Brahma, Antonino Marciano
Using self dual Ashtekar variables, we investigate (at the effective level) the spherically symmetry reduced model of loop quantum gravity, both in vacuum and when coupled to a sca…
Towards self dual Loop Quantum Gravity
Jibril Ben Achour
In this PhD thesis, we introduced a new strategy to investigate the kinematical and physical predictions of self dual Loop Quantum Gravity (LQG) and by-passed the old problem of im…
Analytic continuation of real Loop Quantum Gravity : Lessons from black hole thermodynamics
Jibril Ben Achour, Karim Noui
This contribution is devoted to summarize the recent results obtained in the construction of an "analytic continuation" of Loop Quantum Gravity (LQG). By this, we mean that we cons…
Loop Quantum Cosmology with Complex Ashtekar Variables
Jibril Ben Achour, Julien Grain, Karim Noui
We construct and study Loop Quantum Cosmology (LQC) when the Barbero-Immirzi parameter takes the complex value . We refer to this new quantum cosmology as complex Loop Qua…
Conformally invariant wave equation for a symmetric second rank tensor ("spin-2") in d-dimensional curved background
J. Ben Achour, E. Huguet, J. Renaud
We build the general conformally invariant linear wave operator for a free, symmetric, second-rank tensor field in a d-dimensional () metric manifold, and explicit th…