Stitching the Tapestry of Cosmic Time via Galaxy Redshift Surveys

We share our Universe with around 100 billion galaxies, which have over almost 14 billion years grown to become an incredibly diverse population. They have been shaped by the rise and fall of cosmic star formation, encounters in galaxy groups and clusters, and the incredibly powerful black holes at their hearts. State-of-the-art cosmological simulations have not yet been able to fully describe the diversity of galaxies, a symptom of our current gaps in knowledge. I work with galaxy redshift surveys, which not only map out galaxies in the cosmic web in three-dimensional space, but also in time. By studying these galaxies across the electromagnetic spectrum through carefully crafted techniques, I learn how astrophysical phenomena have shaped the galaxies that lurk in our night sky.

2022 UWA Rising Stars, 1 Nov 2022

What we know about our Universe of galaxies is based on a recipe of energy, matter and time, with a whole heap of assumptions mixed in. Sabine Bellstedt has solved an unexpected problem by fixing one of these assumptions, changing what we know about galaxies and when they formed their stars.

TEDxKingsParkSalon, 1 Sep 2021

Cosmic evolution of star formation and metallicity using ProSpect

SED-fitting techniques, which use multi-wavelength photometry from galaxies in the low-z Universe to infer their star formation histories (SFHs), are becoming an increasingly popular tool to generate the cosmic SFH, an essential ingredient in understanding the build-up of galaxies. Up until now, however, these techniques have not implemented an evolution in the metallicity of individual galaxies. In this talk, I will present results using a new SED-fitting code ProSpect, considering an evolving metallicity, to derive star formation histories of ~7,000 z<0.06 galaxies from the GAMA survey. By implementing a physically-motivated metallicity evolution for individual galaxies, we recover not only the observed cosmic SFH, but we can also extract the cosmic evolution in metallicity. I will show that this implementation has provided a marked improvement when compared with the results of other SED-fitting techniques, and that we are able to recover a realistic evolution of gas-phase metallicity within our sample. As I will show in this talk, this enables us to predict the evolution of the mass-metallicity relation to high-z, and to low stellar masses. Finally, I will also show the resulting cosmic metal mass density derived by this work, and how it relates to observational measurements.

ASTRO3D ECR Astronomers in Australia Seminar Series, 20 May 2021