A Phenomenological Parameterization for Anomalous Accelerations of Interstellar Objects: Thermodynamic Activity as a Scaling Proxy

The anomalous non-gravitational accelerations of interstellar objects (ISOs) such as Oumu challenge standard outgassing models. We propose a simple phenomenological parameterization linking these accelerations to an observable proxy for thermodynamic activity, derived from molecular production rates. A minimum activity scale, estimated heuristically from fundamental constants, regularizes the model. Calibration using Oumu and Borisov is presented; the model's prediction for ATLAS constitutes a pending observational test.

The central prediction is an inverse correlation between acceleration and activity, corresponding to a slope of \(-1\) in a log-log diagram. Additional qualitative expectations include a possible saturation of acceleration at large heliocentric distances and an upper bound on anomalous accelerations.