Making Sense of the Unexpected in the Gravitational-Wave Sky

Introduction

General Relativity (GR) is more than a century old, but is still our best macroscopic description of gravity. Key GR predictions are black holes (BHs) and gravitational waves (GWs), whose spectacular confirmation led to two recent physics Nobel Prizes.

Future of GW Astronomy

The future of GW astronomy, however, is even brighter, since detectors will observe BHs at cosmic dawn and probe their enigmatic event horizon, where GR clashes with quantum mechanics in the information loss paradox. These experiments will measure signals hundreds of times smaller than today, necessarily discovering anomalies and deviations from current predictions, e.g., due to the astrophysical environment.

Fundamental Insights

On the fundamental side, precision GW astronomy will open countless possibilities for understanding the standard model of particle physics (and its extensions), gravity, and cosmology. By itself, however, precision is not knowledge.

Need for a Groundbreaking Framework

To harness the power of these measurements, a groundbreaking framework is urgently needed to solve the very nonlinear equations of GR and develop waveform models to unprecedented accuracy, and to convert these results into concrete interpretation tools.

GWSky's Objectives

GWSky will leverage the world-leading expertise of its PIs in astrophysics, GW-source modeling, particle physics, and GR, and recent paradigm shifts to build an overarching framework answering a fundamental question:

1. When, inevitably, an anomaly in a GW signal is identified, what is it?
   • A gravitational effect not predicted by GR?
   • The influence of nearby matter?
   • Or merely an imprecise calculation of the expected signal?

Implications of Deviations from GR

Even tiny deviations from GR would shake physics to its core, but to claim a deviation from it, one needs to filter out first the contributions from the astrophysical environment, instrumental artifacts, and systematic modeling uncertainties.

Tools for Precision GW Astronomy

GWSky will provide tools to disentangle these contributions, enabling precision GW astronomy with upcoming observational runs and new facilities on the ground and in space.