Gas-to-dust mass ratio map in a Milky-Way-like galaxy from a hydrodynamic simulation.

Gas-to-dust mass ratio map in the Small Magellanic Cloud from Herschel observations.

Tracing ISM physics with evolved dust

Supervisor: Dr Svitlana Zhukovska

Dust grains are tiny solid particles that are present in the interstellar space of any galaxy. They absorb stellar radiation and re-emit it in the infrared wavelength, completely changing the appearance of galaxies. Thermal emission from grains is a commonly used tracer of interstellar gas mass and its evolution, in particular, formation of new stars in galaxies near and far. Such studies assume that interstellar grains are constant and the same as in the local Milky Way. There is however a growing number of observations indicating that dust properties differ not only from one galaxy to another, but also within one galaxy as a function of local physical conditions.

The key question of this project is how the evolutionary changes of dust grains affect the observable characteristics of galactic evolution. With recent numerical hydrodynamic galactic simulations providing an insight into a three-dimensional distribution of evolved dust, it is now possible to investigate theoretically how well grains trace the ISM physics and how this can be improved. To address these questions, the project will employ radiative transfer calculations and generate the spectral energy distribution and dust emission maps for the simulated galactic dust distributions. The synthetic spectra will be compared with observations from ground-based telescopes and recent space missions (Spitzer, Herschel, Planck) and used to make predictions for the James Webb Space Telescope mission (launch in 2021). Another direction of the project is to study extinction of stellar light by interstellar dust. Three-dimensional maps of the interstellar galactic extinction for evolved dust distributions from simulations can be used to link the observed variations of the extinction detected by recent surveys to the grain evolution in the interstellar medium.

Skills: The project will involve work with numerical simulations and radiative transfer codes, so having experience with programming is beneficial. It will also offer the opportunity to collaborate with observers, including international collaborations, and with lab astrophysics.

For more details on this project please contact Dr Svitlana Zhukovska.