Roman CCS White Paper: Balanced Prism Plus Filter Cadence in the High Latitude Time Domain Survey Core Community Survey

TL;DR

The Nancy Grace Roman Space Telescope's Wide Field Imager offers a novel slitless prism spectroscopic capability for high-redshift transient discovery, providing unmatched depth in the near-infrared and influencing survey strategy decisions.

Contribution

This white paper clarifies the unique spectroscopic capabilities of the Roman Space Telescope's prism for high-redshift transient studies and discusses survey optimization considerations.

Findings

RST prism is deeper than ground-based spectrographs in NIR.

Sky location affects survey speed and uniformity.

The prism capability should influence survey cadence planning.

Abstract

The Nancy Grace Roman Space Telescope's (RST) Wide Field Imager (WFI) is equipped with a slitless prism that can be used for spectroscopic discovery and follow-up of explosive transients at high redshift as part of its High Latitude Time Domain Survey. This is new and unique spectroscopic capability, not only for its original purpose for cosmology, but also for other types of explosive transients. This white paper is intended to help make this new capability more clear to the community. The depth of the RST prism compared to ground-based spectrographs is explored, showing that the RST prism will be unrivaled in the observer-frame NIR. The influence of the selected sky locations on the speed and homogeneity of a RST prism survey is also estimated. This unique new capability should be considered when balancing the HLTDS time devoted to cadenced imaging and spectroscopy.