SMA Seminar 03/12/2021

The Triangulum Galaxy (M33), is the third nearest spiral galaxy to us (behind the Milky Way and Andromeda), but is an interesting contrast to those galaxies. With a half-solar metallicity, and a much higher star-formation efficiency, the properties of M33 seem to be significantly different to the other 2 massive spirals in our Local Group, and may offer us more of a look at a 'younger,' or higher redshift galaxy. I'll be talking about the 3 projects that made up my thesis, studying the interplay between the dust, gas, and stars in M33. I will then talk a little about a new project I have been carrying out as part of the PHANGS collaboration. Firstly, I'll present a study of the resolved star-formation law (or Kennicutt-Schmidt law) — how this varies with the resolution it is measured at, and the gas tracer that is used. Secondly, using new SCUBA-2 PI observations of M33, I have created a dust-selected GMC catalogue, studying the gas-to-dust ratios (GDRs) and CO conversion factors in these clouds, as well as hunting for molecular hydrogen that CO may miss. Thirdly, using the data I have brought together over the course of my PhD, I have built a radiative transfer model of M33. This has been to study the sources of dust heating, and the scale at which a local dust-energy balance (i.e. the area at which the emission from dust is from starlight in that same area) is an acceptable assumption. Moving away from M33, I will touch briefly on a project that has just recently been accepted for publication: using the combination of ALMA and MUSE data taken as part of PHANGS, I have calculated the pattern speeds for a number of galaxies. I will show that the pattern speed of a bar correlates with e.g. molecular gas fraction and anti-correlates with the bulge-to-disc ratio. I will also show that using interstellar medium (ISM) tracers to calculate pattern speeds are intrinsically compromised due to their clumpy nature, and produce systematically false pattern speeds