Seminar Speaker

Matthew Hopkins 

Venue

Room G06, Kane Science Building, UCC

Time/Date 

4pm / Monday, 8 Sept, 2025

Title

The Galactic Interstellar Object Population 

Abstract

Sourced from distant planetary systems and forming a huge Galaxy-spanning population, the properties of interstellar objects (ISOs) depend on processes across a range of astrophysical scales. This population plays an active role in Galactic life, potentially seeding planet formation in protoplanetary disks and causing fast radio bursts in collisions with neutron stars. With the imminent Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) set to increase our sample of known ISOs by an order of magnitude, I will present a predicted chemodynamical model of the ISO population derived using the Gaia stellar survey and models of protoplanetary disk chemistry, along with a simulation of ISO discoveries in the LSST. I predict that the Galactic ISO population has a complex velocity distribution which is correlated with both chemical composition and age, and that these features will be retained in the sample discovered by the LSST. Furthermore, the discoverability simulation shows that the LSST will find 5-50 ISOs over 10 years, and constrain the size frequency distribution slope of ISOs with just a few discovered objects. These results mean that the Rubin ISO sample can be used to test models of planetesimal formation, Galactic evolution, and tidal stream formation.