Planet-induced gas and dust substructure feedbacks on disc thermal structure

ABSTRACT Protoplanets can interact with their natal discs and generate gas and dust substructures such as gaps and rings. However, how these planet-induced substructures affect the disc temperature, and how that in turn influences the substructures, remains unclear. We aim to study disc substructures and the thermal structure self-consistently and explore their impact on volatile distribution. To this end, we perform iterative multifluid hydrodynamical and radiative transfer simulations of planet–disc interactions. We find that the temperature in a structured disc deviates significantly from that of a smooth disc due to giant planet formation. In particular, mid-plane temperatures in gaps can increase by tens of Kelvin, leading to volatile sublimation as well as radial shifts and multiplication of ice lines. Comparing our multidust models with previous gas-only models, we find that the former produces slightly shallower gaps and temperatures about 10 K (${\sim} 25 {{\, \rm per\, cent}}$) higher. Furthermore, the temperature at dust rings formed by pressure bumps can drop by several Kelvin, creating volatile freeze-out regions. Nevertheless, the overall mid-plane ice distribution is not strongly sensitive to whether dust is included. We also investigate the effect of varying disc viscosity. Increasing $\alpha$ viscosity from $10^{-4}$ to $10^{-2}$ leads to a roughly 10 K (${\sim} 25 {{\, \rm per\, cent}}$) warmer mid-plane due to enhanced vertical dust mixing. However, higher viscosity suppresses gap opening and reduces the temperature enhancement within gaps. As a result, ice line locations do not follow a simple trend with viscosity. Finally, we propose an observational strategy using the Atacama Large Millimeter/submillimeter Array to test our predicted temperature changes within disc gaps.