Metallicity Madness: Corrections for Roman SN Ia Cosmology from the Rest Frame U Band
| Program ID | 19094 |
|---|---|
| Science Category | Stellar Physics |
| Program Type | Analysis |
| Category | Small |
| Principal Investigator | Cameron Pfeffer |
| PI Institution | University of Hawaii Institute for Astronomy |
| Co-Investigators |
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| Abstract | The Nancy Grace Roman Space Telescope is poised to provide an unprecedented sample of Type Ia Supernovae (SNe Ia) beyond z = 1 with its High Latitude Time Domain Survey (HLTDS). Measurements of these standardizable candles are key to understanding dark energy, but precision cosmology can only be extracted from SNe Ia if their systematics are adequately constrained. Progenitor metallicity is the foremost factor that causes the luminosity of a SN Ia to differ from the value inferred by its light curve width. This pivotal factor varies with redshift, but this trend has not yet been adequately characterized due to a lack of data. Furthermore, some SNe Ia explode shortly after the formation of their systems, while others are delayed by up to 8Gyrs. As a result, there is an uncharacterized distribution of metallicities for a given redshift. Fortunately, Roman will provide the measurements required to measure the metallicity of these SN Ia progenitors in the form of rest-frame U band photometry. In the rising light curve of a SN Ia, the U band probes the unburnt outer layers of the ejecta where the only metals present are those that were present in the progenitor. With the predicted 5,000 SNe Ia to be discovered in the Roman HLTDS Wide Tier, the progenitor metallicity of a large sample of SNe ranging from z = 0.2 to z =1.5 can be determined for the first time. This proposal seeks to provide enhanced precision for Roman cosmology by discerning the effect of varying progenitor metallicities and delay times as a function of redshift. |