Compact binary inspiral: Nature is perfectly happy with a circle

Understand

It is standard lore that gravitational radiation reaction circularizes the orbits of inspiralling binary systems.

• But in recent papers, Loutrel et al.
• have argued that at late times in such inspirals, one measure of eccentricity actually increases, and that this could have observable consequences.
• We show that this variable, the magnitude of the Runge-Lenz vector ($e_{\rm RL}$), is not an appropriate measure of orbital eccentricity, when the eccentricity is smaller than the leading non-Keplerian perturbation of the orbit.