Simulating the interplay between the snowline pebble flux and ongoing planet formation and migration

Abstract

Pebble drift plays a central role in modern planet formation models. In this work we carry out planet formation simulations (including pebble accretion and migration) for a range of disc parameters to investigate (a) the impact of the snowline pebble mass flux on final planet orbits and masses, and (b) the back-reaction of growing and migrating planets on the snowline pebble fluxes in their natal discs. We find a strong correlation between the snowline pebble flux (at the time of protoplanet insertion) and the final planet mass. The correlation is continuous in disks with high turbulence levels ($\alpha=10^{-3}$), but exhibits a step function at lower turbulence ($\alpha=10^{-4}$), with giant planet formation requiring (initial) snowline pebble mass fluxes exceeding $100~\mathrm{M_\oplus Myr^{-1}}$. We find qualitative agreement between pebble mass fluxes inferred for discs aged ${\sim}1~\mathrm{Myr}$ and our planet-containing models, especially for larger disks ($\geq$40 au), high $\alpha$ ($10^{-3}$), and low $v_\mathrm{frag}$ ($3\mathrm{~m~s}^{-1}$). Additionally, giant planets in high turbulence disks are found to perturb the snowline pebble flux only temporarily (for ${\approx}10^{5-6}\mathrm{~yr}$) due to them quickly growing and migrating across the snowline. Our simulations show that currently observed pebble fluxes can indeed be used to constrain planet formation simulations, emphasizing that planet formation via pebble accretion is broadly in agreement with the currently available constraints from disc evolution as provided by JWST.