Wednesday

Type Ia supernovae (SNe Ia) are vital cosmological probes as standardisable candles, due to their brightness and low intrinsic luminosity dispersion. They have been used to reveal the accelerating expansion of the universe, and place constraints on the cosmological parameters. However, there remains a puzzling ∼0.15mag dispersion in their peak magnitudes that is not understood. This has prompted a search for further light curve corrections.
Recent studies have found that the corrected brightness correlates with the stellar mass of the supernova host galaxy. After standardisation, SN Ia in high-mass, passive hosts are brighter than those in lower-mass, star-forming regions. It has been suggested that the stellar mass acts as a proxy for the galactic characteristics and supernova progenitor and could be utilised as an additional light curve correction parameter.
Here, we compare local and global properties of the host galaxies of the Dark Energy Survey 3-year spectroscopically confirmed SNe Ia, with a redshift range of 0.05 z 0.85. We perform photometric measurements of the host and local aperture photometry within a fixed proper distance radius centred around the locations of the supernovae in griz filter bands. Spectral Energy Distribution (SED) fitting is then applied to both the global and local photometry, from which we calculate the host galaxy star formation rate, stellar mass, and rest-frame U-V colour. We compare these quantities against the SN Ia corrected luminosity to find the most effective host galaxy correction to use in cosmological analysis.