#PizzaSeminar
Title: "Improving the Hubble Diagram on Both Axes"
Speaker: Erik Peterson (Duke University)
Various cosmological parameters such as H0 and S8 measured using Type Ia Supernovae (SNe Ia) have been shown to be in tension with measurements from the early universe. We can improve cosmological parameter measurements and reduce scatter on the Hubble Diagram by focusing on both magnitude scatter by leveraging the near-infrared (NIR) and redshift scatter by leveraging galaxy groups. With the DEHVILS sample, one of the largest uniform NIR samples of SN Ia light curves (LCs), we measure and analyze the reduction in Hubble residual scatter as compared to the optical. Using the low redshift sample from Pantheon+ combined with a new sample from the AAT spectrograph, we obtain and average the redshifts of galaxy groups to correct for peculiar velocities and improve scatter on the Hubble Diagram. With the impending arrival of the Roman Space Telescope, which will observe in the NIR and need a well understood low-redshift anchor SN sample, we encourage further analysis on NIR SN Ia LCs and an increased effort to define more galaxy groups.