Tidal Migration Timescales for Exomoons Raised by Planetary Tides

This paper computes a quantitative budget for one aspect of exomoon physics: the subject stated in the title, evaluated from stated assumptions with every number produced by the deposited calculation. Headline results are tau_10Rp_Q1e5_Gyr = 372.81; dadt_10Rp_m_per_yr = 1.88e-03; tau_5Rp_Q1e5_Gyr = 4.119; tau_30Rp_Q1e5_Gyr = 470737.1. A moon orbiting faster than its planet rotates is raised by the tidal bulge it lifts on the planet, and the torque transfers angular momentum from the planetary spin to the orbit. The satellite migrates outward, as the Moon does around the Earth, at a rate set by the planet's Love number, its tidal quality factor, and a steep fifth-power dependence on the ratio of planetary radius to orbital dista The results are compared with published Solar System values and with the constraints attached to reported exomoon candidates where those apply, and the conditions under which the computed budget would change are stated explicitly. Computed from stated assumptions, not measured.