Using galactic bar dynamics to probe the nature of dark matter

The nature of dark matter - the elusive substance making up 85\% of the mass of the Universe and one of the pillars of the standard Lambda Cold Dark Matter, cosmological model - remains a major unsolved mystery of modern physics. While its fundamental properties are as of yet unknown, its existence and properties can be inferred through its gravitational influence on normal (baryonic) matter.

Dark matter interacts gravitationally with stars in spiral galaxies in two intriguing ways: i) it stabilises stellar discs against the formation of elongated, rotating structures, called galactic 'bars' (e.g. Ostriker \& Peebles 1973) and, ii) when bars do form, dark matter inflicts a drag force on them, i.e. 'dynamical friction', causing them to slow down (e.g.

Tremaine \& Weinberg, 1984b). As these processes are mediated via resonant interactions between the bar and dark matter particles, the fraction of galaxies hosting bars, and the bar rotation speed itself, will be highly dependent on the existence and properties of dark matter.

This PhD project will focus on using state-of-the-art models to shed light on the nature of dark matter via its effects on the stellar and gaseous dynamics of spiral galaxies, such as our own Milky Way. This is particularly timely as we are currently living in a golden era of galactic dynamics, thanks to exquisite data of the Milky Way and nearby galaxies from Gaia and ground-based spectroscopic surveys.

We will develop and use state-of-the-art cosmological simulations in $\Lambda$CDM and alternative dark matter scenarios, as well as gas-dynamical models to answer questions such as: -What are the signatures of the resonant interaction between dark matter and bars? -How do these signatures depend on the nature of dark matter?

-What is the effect of different dark matter scenarios on the dynamical friction exerted on galactic bars? -How much dark matter is there in spiral galaxies (both low- and high-mass) in the local Universe?

The student will have the opportunity to develop and work with cosmological simulations and/or gas-dynamical models, and compare these models to current and upcoming observational data.