Compact Binary Coalescences in Dense Gaseous Environments Can Pose as ones in Vacuum

Understand

The gravitational-wave events observed by the LIGO-Virgo-KAGRA collaboration are attributed to compact binary coalescences happening in vacuum.

• However, several studies suggest that gaseous environments may play a significant role in the formation and evolution of compact binaries.
• Why have we not seen environmental effects in LVK signals? While matched-filtering remains the most effective technique for gravitational-wave searches, it comes with a burden: we might only observe signals that align with our (vacuum) expectations, potentially missing unexpected or unknown phenomena.
• Even more concerning is the possibility that environmental effects could mimic vacuum waveforms, introducing biases in parameter estimation and impacting population studies.