Eikonal black hole ringings in generalized energy-momentum squared gravity

Understand

In the scope of black hole spectroscopy, several attempts have been made in the past decades in order to test black holes or gravitational theories via black hole quasinormal modes.

• In the eikonal approximation, the quasinormal modes are generically associated with the photon ring of the black hole.
• This correspondence is valid for most cases in general relativity, but may not be true in other theories of gravity.
• In this paper, we consider the generalized energy-momentum squared gravity in which matter fields are non-minimally coupled to geometry.