ANGUS sees more faint and small galaxies in the early Universe

The seemingly peaceful night sky can make us forget how wild a place the Cosmos actually is. Supernovae, for instance, are the explosions of massive stars that end their lives violently. They are so energetic that they can affect the fate of their entire host galaxy. They impact on the chemical composition of their environment by expelling heavy elements that had been created inside stars when they were still young and bright. Supernovae hence alter the rate at which new stars form, and sometimes they can suppress star formation and even destroy their host altogether. Worse still, supermassive black holes greater than 1 billion solar masses accrete the surrounding matter in their host galaxy, grow ever larger with time and turn into the most luminous and energetic persistent sources of radiation in the Universe. The fate of the host galaxy changes in their presence.

In a recent work, CAASTRO PhD student Antonios Katsianis and his supervisors Dr Edoardo Tescari and Professor Stuart Wyithe at the University of Melbourne present the second paper of a series which reports on the numerical results of the CAASTRO-supported AustraliaN GADGET-3 early Universe Simulationsproject, or ANGUS for short. The team used a set of cosmological simulations that focused on the early stages of the Universe to study the mass of stars inside galaxies and how these can change due to supernova explosions and supermassive black holes. While they found that there was a good agreement between numerical results and observations, they also note that their simulations produced more faint objects than real observations do.

The authors therefore predict that future deep surveys with advanced instrumentation will find a large population of faint galaxies with low stellar masses. In addition, they demonstrated that observations possibly underestimated the masses of the observed objects due to false methodology. Recent observations of the young Universe obtained from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey support the predictions of the ANGUS project and report results consistent with the models presented here.

Publication details:

Antonios Katsianis, Edoardo Tescari, Stuart Wyithe in MNRAS (2015) “The stellar mass function and star formation rate-stellar mass relation of galaxies at z ~ 4 – 7”