Dark energy Analysis for W and Next-generation Surveys

Type Ia Supernovae (SNe Ia) remain unparalleled probes of astronomical distances and provide crucial constraints when measuring the properties of dark energy. But recent cosmological analyses with SNe Ia have pushed the boundaries of our physical understanding of these standardisable candles. The largest source of cosmological systematic uncertainty for SNe Ia is the impact of astrophysical effects from both extrinsic host galaxy properties (such as dust content) and the intrinsic effects of the SN. Without better understanding how SNe Ia interact with, and are co-dependent on, their host environment, the key cosmology programs of future surveys, such as the legacy survey of space and time (LSST) from the Rubin Observatory, will not reach their goals.My MCSA Fellowship will make use of a new high-quality sample of 3,000 SNe Ia and their hosts taken from the Zwicky Transient Facility (ZTF) and the internationally-recognised expertise of the host, the University of Southampton. I will use this as a basis to better understand SNe Ia for use in cosmology and in astrophysics. I will create a catalogue of the host galaxies with high-quality measurements across the electromagnetic spectrum, providing global and local measurements of galaxy properties to probe how they impact SNe Ia. Then, I will use integral field spectroscopy of local SN hosts to provide hyper-local measurements at the site of the SN Ia explosion, augmenting the statistics of the host galaxy catalogue with in-depth measurements. These two work packages will then be combined to assess the impact of these host galaxy effects on cosmology, determining which galaxy evolution processes drive the observed correlations of SN Ia brightness, and the ideal tracer to use for the high-statistics cosmology analyses of Rubin/LSST. This final work package will also shed light on how SNe Ia may be used as a probabilistic tracer for host galaxy evolution, providing a new and independent tool for use in astronomy.