Circumstellar dust: A nexus of performance, calibration, and science potential in the Roman coronagraph technology demonstration
Schuyler Wolff / University of Arizona, PI
Planetary system architectures include rocky planets, gas giant planets, and dusty debris. All three components will appear in high contrast images from NASA’s future Habitable Worlds Observatory (HWO). Along with its key flight demonstration of coronagraphy with precision wavefront control, the Roman Coronagraph (RC) will advance our understanding of how well HWO will be able to study these three elements of exoplanetary systems. The instrument should not only produce the first direct detection of a giant planet in reflected starlight, but can also provide unprecedented views of the spatial structure and scattering properties of circumstellar dust. The strong potential of RC polarimetry allows disk modeling degeneracies to be broken, allowing for the extraction of information on the size, composition and porosity of the scattering particles. We suggest that the Roman Coronagraph Team work to fully define the instrument’s science potential for exozodi and debris disk studies.
Our proposed involvement in the RC Team focuses on two areas. The first focus area is to use the needs of exozodi and debris disk imaging to motivate investigations of instrument performance and calibration for extended sources. 1.) By fully exercising the built-in polarimetry mode of RC in Band 1 and Band 4, we will learn how well its instrumental polarization can be modeled, the limits to polarization sensitivity including the efficacy of polarimetric differential imaging at very high contrast levels, and the accuracy of its polarimetric calibration. From such work the RC team can gain confidence that polarized light can be a science tool for RC and eventually HWO, and not an optical design issue that curtails high contrast performance. 2.) By investigating the limits to LOWFS operation, our intended studies will map out the parameter space of dark hole contrast versus target star brightness - defining the full extent of what RC and eventually HWO can achieve in the way of disk and exozodi detections in the solar neighborhood. 3.) Building from the PI’s ongoing involvement in JWST coronagraphy, we will provide a customized pipeline module for analyzing tech demo data of extended disk sources.
Informed by the results of the above, our second focus area is to develop options for two potential community projects that would figure into a decision on RC utilization beyond the tech demo phase. 4.) By leading the RC team and broader community in the definition and preparation of a ready-to-execute exozodi survey program, we will enable a timely NASA HQ decision on whether the benefits of an exozodi survey would justify the required resources, reducing the risk to the primary Roman Science mission and (should the survey go ahead) to HWO mission lifetime requirements. 5.) By building a database of disk models for the known debris disks accessible to RC, we can gain confidence that tech demo observations of extended sources will achieve their goals while simultaneously laying the groundwork for a possible future survey of inner warm debris disks with RC.
The success of future facilities like the Roman Coronagraph will require scientists with both a working knowledge of the technical challenges of high contrast imaging and an understanding of the fundamental research questions. We believe that our expertise in instrument commissioning and calibration, in disk science and disk modeling, and in data pipeline development will serve the community and the Roman Coronagraph Team.