Nature Abhors a Circle

TL;DR

This paper reveals that in binary inspirals, the orbital eccentricity can grow secularly after initially decreasing, challenging previous assumptions and impacting gravitational wave detection strategies.

Contribution

It demonstrates that small osculating eccentricity can increase secularly due to radiation reaction forces, a novel insight into binary inspiral dynamics.

Findings

Eccentricity growth occurs after initial decrease in inspirals.

The behavior impacts gravitational wave signal modeling.

Physical interpretation of eccentricity growth is provided.

Abstract

The loss of orbital energy and angular momentum to gravitational waves produced in a binary inspiral forces the orbital eccentricity to adiabatically evolve and oscillate. For comparable-mass binaries, the osculating eccentricity is thought to decrease monotonically in the inspiral. Contrary to this, we here show that, once the osculating eccentricity is small enough, radiation reaction forces it to grow secularly before the binary reaches the last stable orbit. We explore this behavior, its physical interpretation and consequences, and its potential impact on future gravitational wave observations.