333 citations · 821 across the 19 of their papers we have counts for
20 papers
Jet launching from the Kerr black hole magnetosphere: An electrogeodesic approach
Jibril Ben Achour, Ileyk El Mellah, Eric Gourgoulhon
The launch of relativistic jets of plasma on astrophysical to cosmological scales is observed in a variety of astrophysical sources, from active galactic nuclei to X-ray binaries.…
Symmetries of cosmological perturbations: The residual low-multipole ambiguity
Jibril Ben Achour, Etera Livine, Vincent Vennin
In cosmology, long-wavelength modes are related to large-gauge transformations (LGT), i.e. changes of coordinates that modify the physical geometry of the cosmological patch. These…
A Circular Disformal Kerr Black Hole
Jibril Ben Achour, Adolfo Cisterna, Hugo Roussille
The Kerr solution is the cornerstone of General Relativity (GR) for modelling astrophysical rotating black holes and for testing GR through gravitational-wave observations and blac…
Algebraically special perturbations of the Kerr black hole: a metric formulation
Jibril Ben Achour, Clara Montagnon, Hugo Roussille
Perturbations of the Kerr black hole are notoriously difficult to describe in the metric formalism and are usually studied in terms of perturbations of the Weyl scalars. In this wo…
Quantum Gravity, Hydrodynamics and Emergent Cosmology: A Collection of Perspectives
Jibril Ben Achour, Dario Benedetti, Martin Bojowald +17
This collection of perspective pieces captures recent advancements and reflections from a dynamic research community dedicated to bridging quantum gravity, hydrodynamics, and emerg…
DHOST theories as disformal gravity: From black holes to radiative spacetimes
Jibril Ben Achour
This manuscript reviews the construction of exact solutions describing both (rotating) black holes and non-linear radiative spacetimes in the context of degenerate higher order sca…
The Cosmological Spinor
Jibril Ben Achour, Etera R. Livine
We build upon previous investigation of the one-dimensional conformal symmetry of the Friedman-Lema\^ itre-Robertson-Walker (FLRW) cosmology of a free scalar field and make it expl…
Towards consistent black-to-white hole bounces from matter collapse
Jibril Ben Achour, Suddhasattwa Brahma, Shinji Mukohyama +1
This article presents a new model-independent constraint for bouncing black hole geometries. Using the thin shell formalism, this constraint sets a bound on the minimal allowed rad…
Bouncing compact objects. Part II: Effective theory of a pulsating Planck star
Jibril Ben Achour, Jean-Philippe Uzan
This article presents an effective quantum extension of the seminal Oppenheimer-Snyder (OS) collapse in which the singularity resolution is modeled using the effective dynamics of…
Bouncing compact objects I: Quantum extension of the Oppenheimer-Snyder collapse
Jibril Ben Achour, Suddhasattwa Brahma, Jean-Philippe Uzan
This article proposes a generalization of the Oppenheimer-Snyder model which describes a bouncing compact object. The corrections responsible for the bounce are parameterized in a…
Hairy black holes in DHOST theories: Exploring disformal transformation as a solution-generating method
Jibril Ben Achour, Hongguang Liu, Shinji Mukohyama
Solutions-generating methods based on field redefinitions, such as conformal mapping, play an important role in investigating exact solutions in modified gravity. In this work, we…
Protected Symmetry in Quantum Cosmology
Jibril Ben Achour, Etera R. Livine
The polymer quantization of cosmological backgrounds provides an alternative path to the original Wheeler-de Witt (WdW) quantum cosmology, based on a different representation the c…
Hairy Schwarzschild-(A)dS black hole solutions in DHOST theories beyond shift symmetry
Jibril Ben Achour, Hongguang Liu
We derive the general conditions for a large family of shift symmetry breaking degenerate higher order scalar-tensor (DHOST) theories to admit stealth black hole solutions. Such bl…
Polymer Quantum Cosmology: Lifting quantization ambiguities using a conformal symmetry
Jibril Ben Achour, Etera R. Livine
In this letter, we stress that the simplest cosmological model consisting in a massless scalar field minimally coupled to homogeneous and isotropic gravity has an in-built $\SL(2,\…
Polymer Schwarzschild black hole: An effective metric
Jibril Ben Achour, Frédéric Lamy, Hongguang Liu +1
We consider the modified Einstein equations obtained in the framework of effective spherically symmetric polymer models inspired by Loop Quantum Gravity. When one takes into accoun…
New Hamiltonians for loop quantum cosmology with arbitrary spin representations
Jibril Ben Achour, Suddhasattwa Brahma, Marc Geiller
In loop quantum cosmology, one has to make a choice of SU(2) irreducible representation in which to compute holonomies and regularize the curvature of the connection. The systemati…
Analytic continuation of the rotating black hole state counting
Jibril Ben Achour, Karim Noui, Alejandro Perez
In loop quantum gravity, a spherical black hole can be described in terms of a Chern-Simons theory on a punctured 2-sphere. The sphere represents the horizon. The punctures are the…
Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations
Jibril Ben Achour, David Langlois, Karim Noui
We consider all degenerate scalar-tensor theories that depend quadratically on second order derivatives of a scalar field, which we have identified in a previous work. These theori…
Black holes as gases of punctures with a chemical potential: Bose-Einstein condensation and logarithmic corrections to the entropy
Olivier Asin, Jibril Ben Achour, Marc Geiller +2
We study the thermodynamical properties of black holes when described as gases of indistinguishable punctures with a chemical potential. In this picture, which arises from loop qua…
Testing the role of the Barbero-Immirzi parameter and the choice of connection in Loop Quantum Gravity
Jibril Ben Achour, Marc Geiller, Karim Noui +1
We study the role of the Barbero-Immirzi parameter and the choice of connection in the construction of (a symmetry-reduced version of) loop quantum gravity. We start with the f…