Institute of Astronomy

Spiral arms in galaxies and GMC formation

SpeakerTalk DateTalk Series
Clare Dobbs (Exeter)8 November 2018Institute of Astronomy Colloquia


The mechanisms for forming Giant Molecular Clouds (GMCs) in galaxies, and the role of spiral arms on GMC and star formation, are still unclear. I will discuss the different GMC formation mechanisms and present evidence from numerical simulations which suggest that GMCs form through a combination of cloud-cloud collisions and self gravity. From galaxy scale simulations of GMC evolution, I will show that we are able to reproduce the observed characteristics of GMCs. I will then present results from simulations of galaxies with different types of spiral arms. These find little dependence of the properties of the GMCs on the spiral arm type, and only a modest (factor of 2) change in the star formation rate. I will again relate this to observational analysis of the role of spiral arms. Finally I will show simulations designed to model the nearby galaxy M33 which reproduce the observed spiral structure remarkably well. A comparison between the properties of the GMCs in the simulated versus real M33 show very good agreement, but also highlight that different behaviour in the mass spectra can occur purely as a result of the clump-finding algorithm used.