RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 07 September 2017, 11:00-12:00; Duffield Lecture Theatre

Simon Mutch

"The Epoch of Reionization and DRAGONS"

During the Epoch of Reionization the first sources of energetic photons (stars and quasars) ionized the inter-galactic medium, forever altering the conditions for future star formation and galaxy growth. Observing the 21cm emission from neutral hydrogen during this period (which is redshifted to radio wavelengths here on Earth) and its evolution is a key science driver behind the Murchison Wide-field Array (MWA) and the SKA. Future IR observations of high redshift galaxies with JWST and the Wide Field IR Survey Telescope (WFIRST) will further expand our knowledge about the sources driving reionization. In order to fully leverage the combined results of these radio and IR observations, we need to be able to simultaneously model high-redshift galaxy formation and large scale cosmic reionization. However, this is a difficult task. In this talk I will give a brief overview of some of the associated challenges before moving on to discuss semi-analytics as a useful and powerful compliment to other simulation methods. I will then introduce the Dark-ages Reionization And Galaxy Observables from Numerical Simulations (DRAGONS) programme, and specifically Meraxes, the first semi-analytic galaxy formation model to include a temporally and spatially coupled treatment of galaxy growth and reionization. Finally, I’ll demonstrate the success of this model in reproducing a number of key observables across a broad range of redshifts, as well as it’s utility for investigating a number of important topics such as the ionizing photon budget, 21cm power-spectra, galaxy sizes and the relative importance of AGN for reionization.