Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders
about the fundamental theory of nature at play in the extreme gravity regime, where the …

For ultra compact objects, light rings and fundamental photon orbits (FPOs) play a pivotal
role in the theoretical analysis of strong gravitational lensing effects, and of BH shadows in …

The dawn of the twenty-first century came with very positive prospects for gravity, cosmology,
and astrophysics. Technological progress made it possible for cosmology to enter to its …

In the present Letter, we consider a class of extended scalar-tensor-Gauss-Bonnet (ESTGB)
theories for which the scalar degree of freedom is excited only in the extreme curvature …

Recently there has been a surge of interest in regularizing, a D→ 4 limit of, the Einstein-
Gauss-Bonnet (EGB) gravity, and the resulting regularized 4D EGB gravity has nontrivial …

The LIGO/Virgo detections of binary black hole mergers marked a watershed moment in
astronomy, ushering in the era of precision tests of Kerr dynamics. We review theoretical and …

Scalar fields coupled to the Gauss-Bonnet invariant can undergo a tachyonic instability,
leading to spontaneous scalarization of black holes. Studies of this effect have so far been …

The observation of the inspiral and merger of compact binaries by the LIGO/Virgo
collaboration ushered in a new era in the study of strong-field gravity. We review current and …

The gravitational waves emitted in the ringdown phase of binary black hole coalescence are
a unique probe of strong gravity. At late times in the ringdown, these waves can be …

One of the most promising strategies to test gravity in the strong-field, large curvature regime
is gravitational spectroscopy: the measurement of black hole quasinormal modes from the …