Origin and evolution of two-component debris discs and an application to the q$^1$ Eridani system

TL;DR

This paper investigates the origin of two-component debris discs, proposing a scenario where giant planets carve gaps in planetesimal discs, leading to stable inner and outer belts, and applies this model to the q$^1$ Eridani system.

Contribution

It introduces a detailed collisional evolution model for two-component debris discs formed by planetary carving, aligning with observational data of q$^1$ Eridani.

Findings

Inner disc can retain more material at older ages than previously thought.

The scenario matches thermal emission and scattered light observations of q$^1$ Eridani.

Supports a Solar System-like architecture with outer Kuiper belt, inner asteroid belt, and intermediate planets.

Abstract

Many debris discs reveal a two-component structure, with an outer Kuiper-belt analogue and a warm inner component whose origin is still a matter of debate. One possibility is that warm emission stems from an "asteroid belt" closer in to the star. We consider a scenario in which a set of giant planets is formed in an initially extended planetesimal disc. These planets carve a broad gap around their orbits, splitting up the disc into the outer and the inner belts. After the gas dispersal, both belts undergo collisional evolution in a steady-state regime. This scenario is explored with detailed collisional simulations involving realistic physics to describe a long-term collisional depletion of the two-component disc. We find that the inner disc may be able to retain larger amounts of material at older ages than thought before on the basis of simplified analytic models. We show that the proposed scenario is consistent with a suite of thermal emission and scattered light observational data for a bright two-temperature debris disc around a nearby solar-type star q$^1$ Eridani. This implies a Solar System-like architecture of the system, with an outer massive "Kuiper belt", an inner "asteroid belt", and a few Neptune- to Jupiter-mass planets in between.