The History of the Solar System's Debris Disc: Observable Properties of the Kuiper Belt

TL;DR

This paper models the observable infrared properties of the Kuiper belt throughout Solar System history, linking debris disc evolution to the Late Heavy Bombardment and assessing detectability of such events in other star systems.

Contribution

It introduces a method to convert n-body simulation results into observable IR signatures, incorporating realistic grain properties and size distributions, and compares these with observed debris discs.

Findings

The Solar System was among the brightest debris discs before the LHB.

A significant IR emission increase occurs during the LHB, fading within 30 Myr at 24 μm.

Debilitation events like the LHB are rare, occurring in less than 12% of Sun-like stars.

Abstract

The Nice model of Gomes et al. (2005) suggests that the migration of the giant planets caused a planetesimal clearing event which led to the Late Heavy Bombardment (LHB) at 880 Myr. Here we investigate the IR emission from the Kuiper belt during the history of the Solar System as described by the Nice model. We describe a method for easily converting the results of n-body planetesimal simulations into observational properties (assuming black-body grains and a single size distribution) and further modify this method to improve its realism (using realistic grain properties and a three-phase size distribution). We compare our results with observed debris discs and evaluate the plausibility of detecting an LHB-like process in extrasolar systems. Recent surveys have shown that 4% of stars exhibit 24 um excess and 16% exhibit 70 um excess. We show that the Solar System would have been amongst the brightest of these systems before the LHB at both 24 and 70 um. We find a significant increase in 24 um emission during the LHB, which rapidly drops off and becomes undetectable within 30 Myr, whereas the 70 um emission remains detectable until 360 Myr after the LHB. Comparison with the statistics of debris disc evolution shows that such depletion events must be rare occurring around less than 12% of Sun-like stars and with this level of incidence we would expect approximately 1 of the 413 Sun-like, field stars so far detected to have a 24 um excess to be currently going through an LHB. We also find that collisional processes are important in the Solar System before the LHB and that parameters for weak Kuiper belt objects are inconsistent with the Nice model interpretation of the LHB.