# Black holes beyond General Relativity: shadows, stability, and nonlinear evolution

### APA

Held, A. (2021). Black holes beyond General Relativity: shadows, stability, and nonlinear evolution. Perimeter Institute. https://pirsa.org/21120021

### MLA

Held, Aaron. Black holes beyond General Relativity: shadows, stability, and nonlinear evolution. Perimeter Institute, Dec. 09, 2021, https://pirsa.org/21120021

### BibTex

@misc{ pirsa_PIRSA:21120021, doi = {10.48660/21120021}, url = {https://pirsa.org/21120021}, author = {Held, Aaron}, keywords = {Strong Gravity}, language = {en}, title = {Black holes beyond General Relativity: shadows, stability, and nonlinear evolution}, publisher = {Perimeter Institute}, year = {2021}, month = {dec}, note = {PIRSA:21120021 see, \url{https://pirsa.org}} }

Aaron Held Friedrich Schiller University Jena

## Abstract

Guided by the principles of effective field theory (EFT), I will discuss three avenues to constrain physics beyond General Relativity with black-hole observations.

1) Shadows: Without specifying any particular gravitational dynamics, I will discuss image features of black-hole shadows in general parameterizations and their relation to fundamental-physics principles like (i) regularity (no remaining curvature singularity), (ii) simplicity (a single new-physics scale), and (iii) locality (a new-physics scale set by local curvature).

2) Stability: Specifying the linearized dynamics around black-hole spacetimes determines the onset of potential instabilities and connects to the ringdown phase of gravitational waves. I will delineate how said instabilities can constrain the EFT of gravity, theories of low-scale dark energy, as well as ultralight dark matter.

3) Nonlinear evolution: The larger the probed curvature scale, the tighter the constraints on new gravitational physics. Making full use of experimental data, thus relies on predictions in the nonlinear regime of binary mergers. I will present recent progress towards achieving stable numerical evolution for the EFT of gravity up to quadratic order in curvature.

Zoom Link: https://pitp.zoom.us/j/98276687334?pwd=UnM2dElacWNtempQUHJMNVlaNHgyUT09