Simulations of polarimetric observations of debris disks through the Roman Coronagraph Instrument

TL;DR

This paper presents a simulation framework for polarimetric observations of debris disks using the Roman Coronagraph Instrument, including modeling of instrumental effects, noise, and data processing to estimate polarization.

Contribution

It introduces a comprehensive mathematical model and simulation pipeline for polarized debris disk imaging with the Roman CGI, accounting for instrumental and observational uncertainties.

Findings

Achieved a polarization fraction measurement of 0.4±0.0251 after post-processing.

Demonstrated the impact of instrumental polarization and noise on polarization measurements.

Provided a validated simulation approach for future debris disk observations with Roman.

Abstract

The Roman coronagraph instrument will demonstrate high-contrast imaging technology, enabling the imaging of faint debris disks, the discovery of inner dust belts, and planets. Polarization studies of debris disks provide information on dust grains' size, shape, and distribution. The Roman coronagraph uses a polarization module comprising two Wollaston prism assemblies to produce four orthogonally polarized images ($I_{0}$, $I_{90}$, $I_{45}$, and $I_{135}$), each measuring 3.2 arcsecs in diameter and separated by 7.5 arcsecs in the sky. The expected RMS error in the linear polarization fraction measurement is 1.66\% per resolution element of 3 by 3 pixels. We present a mathematical model to simulate the polarized intensity images through the Roman CGI, including the instrumental polarization and other uncertainties. We use disk modeling software, MCFOST, to model $q$, $u$, and polarization intensity of the debris disk, Epsilon-Eridani. The polarization intensities are convolved with the coronagraph throughput incorporating the PSF morphology. We include model uncertainties, detector noise, speckle noise, and jitter. The final polarization fraction of 0.4$\pm$0.0251 is obtained after the post-processing.