148 citations · 1.2k across the 38 of their papers we have counts for
18 papers · 1 filter
Breaking black-hole uniqueness at supermassive scales
Astrid Eichhorn, Pedro G. S. Fernandes, Aaron Held +1
In general relativity, all vacuum black holes are described by the Kerr solution. Beyond general relativity, there is a prevailing expectation that deviations from the Kerr solutio…
Disentangling photon rings beyond General Relativity with future radio-telescope arrays
Raúl Carballo-Rubio, Héloïse Delaporte, Astrid Eichhorn +1
New physics beyond General Relativity can modify image features of black holes and horizonless spacetimes and increase the separation between photon rings. This motivates us to exp…
Nonlinear Evolution of Quadratic Gravity in 3+1 Dimensions
Aaron Held, Hyun Lim
We present a numerically stable system of (3+1) evolution equations for the nonlinear gravitational dynamics of quadratic-curvature corrections to General Relativity (Quadratic Gra…
Global and Local Stability for Ghosts Coupled to Positive Energy Degrees of Freedom
Cédric Deffayet, Aaron Held, Shinji Mukohyama +1
Negative kinetic energies correspond to ghost degrees of freedom, which are potentially of relevance for cosmology, quantum gravity, and high energy physics. We present a novel wid…
Black holes in asymptotically safe gravity and beyond
Astrid Eichhorn, Aaron Held
Asymptotically safe quantum gravity is an approach to quantum gravity that achieves formulates a standard quantum field theory for the metric. Therefore, even the deep quantum grav…
Instability of spherically-symmetric black holes in Quadratic Gravity
Aaron Held, Jun Zhang
We investigate the linear stability of the two known branches of spherically-symmetric black holes in Quadratic Gravity. We extend previous work on the long-wavelength (Gregory-Laf…
Quantum gravity lights up spinning black holes
Astrid Eichhorn, Aaron Held
Quantum-gravity effects in black holes are generally expected to be unobservable if they set in at transplanckian curvature scales. Here, we challenge this expectation. A near-crit…
Universal signatures of singularity-resolving physics in photon rings of black holes and horizonless objects
Astrid Eichhorn, Aaron Held, Philipp-Vincent Johannsen
Within quantum-gravity approaches and beyond, different mechanisms for singularity resolution in black holes exist. Under a set of assumptions that we spell out in detail, these me…
Scale-invariance at the core of quantum black holes
Johanna N. Borissova, Aaron Held, Niayesh Afshordi
We study spherically-symmetric solutions to a modified Einstein-Hilbert action with Renormalization Group scale-dependent couplings, inspired by Weinberg's Asymptotic Safety scenar…
Parameterizations of black-hole spacetimes beyond circularity
Héloïse Delaporte, Astrid Eichhorn, Aaron Held
We discuss parameterizations of black-hole spacetimes in and beyond General Relativity in view of their symmetry constraints: within the class of axisymmetric, stationary spacetime…
Schwarzschild quasi-normal modes of non-minimally coupled vector fields
Sebastian Garcia-Saenz, Aaron Held, Jun Zhang
We study perturbations of massive and massless vector fields on a Schwarzschild black-hole background, including a non-minimal coupling between the vector field and the curvature.…
Invariant Renormalization-Group improvement
Aaron Held
Renormalization-Group (RG) improvement has been frequently applied to capture the effect of quantum corrections on cosmological and black-hole spacetimes. This work utilizes an alg…
Destabilization of black holes and stars by generalized Proca fields
Sebastian Garcia-Saenz, Aaron Held, Jun Zhang
We demonstrate that black holes and stars in general relativity can be destabilized by perturbations of non-minimally coupled vector fields. Focusing on static and spherically symm…
Nonlinear Dynamics of Quadratic Gravity in Spherical Symmetry
Aaron Held, Hyun Lim
We present the first numerically stable nonlinear evolution for the leading-order gravitational effective field theory (Quadratic Gravity) in the spherically-symmetric sector. The…
From a locality-principle for new physics to image features of regular spinning black holes with disks
Astrid Eichhorn, Aaron Held
Current observations present unprecedented opportunities to probe the true nature of black holes, which must harbor new physics beyond General Relativity to provide singularity-fre…
Image features of spinning regular black holes based on a locality principle
Astrid Eichhorn, Aaron Held
To understand the true nature of black holes, fundamental theoretical developments should be linked all the way to observational features of black holes in their natural astrophysi…
Asymptotic safety casts its shadow
Aaron Held, Roman Gold, Astrid Eichhorn
We set out to bridge the gap between regular black-hole spacetimes and observations of a black-hole shadow by the Event Horizon Telescope. We explore modifications of spinning and…
Viability of quantum-gravity induced ultraviolet completions for matter
Astrid Eichhorn, Aaron Held
We highlight how the existence of an ultraviolet completion for interacting Standard-Model type matter puts constraints on the viable microscopic dynamics of asymptotically safe qu…