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Improving SN Ia Standardization with a First Systematic Study of Spectral Time Series with Roman
Program ID 19055
Science Category Stellar Physics
Program Type Analysis
Category Medium
Principal Investigator Lauren Aldoroty
PI Institution University of Maryland, Baltimore County/NASA Goddard Space Flight Center
Co-Investigators
  • James DerKacy (Space Telescope Science Institute / STScI)
  • Rebekah Hounsell (University of Maryland, Baltimore County/NASA Goddard Space Flight Center)
  • Maria Acevedo (Duke University)
  • Benjamin Rose (Baylor University)
  • Ann Isaacs (University of Minnesota)
  • Massimo Griggio (Space Telescope Science Institute / STScI)
  • Jillian Paulin (University of Pennsylvania)
  • David Rubin (University of Hawaii)
  • Russell Ryan (Space Telescope Science Institute / STScI)
  • Daniel Scolnic (Duke University)
  • Nao Suzuki (Lawrence Berkeley National Laboratory)
Abstract The most urgent outstanding question in cosmology is about the nature of dark energy—does it evolve with time, or is it constant? Type Ia Supernovae (SNe Ia) are key objects in cosmological analysis; due to their standardizability, they can be used to measure distances to their host galaxies and were used in the discovery of dark energy. In the era of large surveys like the Nancy Grace Roman Space Telescope’s (Roman) High-Latitude Time Domain Survey (HLTDS), the dominant source of error in SN Ia cosmology is due to intrinsic variations between the SNe Ia themselves, as well as their host environments. The proposed work aims to use prism spectra from Roman’s pilot HLTDS, as well as the first six months of the core HLTDS, to holistically study SN physics, their evolution over redshift, and their host environments to paint a comprehensive picture of the effects of SN Ia variation on cosmology with Roman data. The first phase of the proposed analysis is a demographics study in which we will verify correlations found in the literature between SN Ia properties and their host galaxy properties. We will focus on quantities with extensive prior work describing their implications on progenitors and cosmological results, primarily the velocity of the Si II 6355 absorption line and the local specific star formation rate. This portion of the analysis will allow the first statistical separation between dust-induced and physics-induced reddening in a cosmological SN Ia sample, due to Roman’s NIR filters. The second phase will use the recovered correlations to investigate any effect on Hubble residuals, as well as use the spectral twins method to statistically search for varying components in spectra in a higher-dimensional space than in the first phase of the analysis. Upon completion of the proposed work, we will have carried out the required prerequisite studies of SN Ia systematics to maximize the potential of any precision SN Ia cosmology analysis with Roman.