Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion

Type Ia supernovae (SNe Ia) provide valuable cosmological constraints independent from the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAO). While the most recent and largest single sample of SNe Ia from the Dark Energy Survey (DES) number around 1600, the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will discover about 1 million SNe Ia. As we pursue the tightest SN Ia cosmological constraints from LSST, there are new challenges we must overcome in the SN Ia flux measurements and redshift measurements, both of which are crucial for high-precision cosmology. 

In this talk, I will give an overview of how investigating wavelength-dependent atmospheric effects can improve both the flux measurements and the redshift measurements - neither of which have been utilized in SN Ia cosmology until recently. While correcting for such effects in our flux measurements will be important for LSST, wavelength-dependent atmospheric effects can additionally provide a measurement of redshifts from astrometry that are nearly-independent from conventional photometric redshifts. Combining these astrometric redshifts with photometric redshifts will be especially useful for LSST since we will not have enough spectroscopic resources to follow up the vast number of LSST SNe Ia.

Towards the end of the talk, I will also briefly describe what we can achieve with LSST SN Ia observations, especially by combining them with other cosmological probes in a way that has not been done before.