Frequency contamination from new fundamental fields in black hole ringdowns

TL;DR

This paper explores how new fundamental fields can contaminate black hole ringdown signals, highlighting limitations of current models and proposing a comprehensive approach to include these effects in gravitational wave analysis.

Contribution

It introduces a general framework for modeling black hole ringdowns with additional fields, extending beyond traditional quasinormal mode analysis in General Relativity.

Findings

Classified deviations in QNM frequencies due to new fields.

Constructed a general ansatz for metric perturbations with extra fields.

Discussed implications for theory-agnostic tests of GR using gravitational waves.

Abstract

We revisit the modelling of black hole ringdown beyond General Relativity (GR), emphasizing the limitations of approaches that rely solely on shifted quasinormal mode (QNM) frequencies. Starting from modified Teukolsky equations in such scenarios, we classify the distinct types of deviations that can arise -- those shifting QNM frequencies, and those introducing additional frequencies associated with extra fields. We then construct the most general ansatz for metric perturbations in this context and discuss its implications for QNM modelling and theory-agnostic tests of GR using gravitational wave data.