High-contrast integral field spectropolarimetry of planet-forming disks with SCExAO/CHARIS

TL;DR

This paper presents a new high-contrast NIR spectropolarimetric imaging technique using SCExAO/CHARIS for studying planet-forming disks, enabling detailed characterization of disk structures and potential protoplanets at small angular separations.

Contribution

Introduction of a novel high-contrast integral field spectropolarimetry mode with SCExAO/CHARIS for detailed analysis of planet-forming disks in the near-infrared.

Findings

Preliminary results on two young planet-forming disks.

Enhanced ability to confirm protoplanets and analyze disk structures.

Improved characterization of dust grain populations.

Abstract

We describe a new high-contrast imaging capability well suited for studying planet-forming disks: near-infrared (NIR) high-contrast spectropolarimetric imaging with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system coupled with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) integral field spectrograph (IFS). The advent of extreme adaptive optics (AO) systems, like SCExAO, has enabled recovery of planet-mass companions at the expected locations of gas-giant formation in young disks alongside disk structures (such as gaps or spirals) that may indicate protoplanet formation. In combination with SCExAO, the CHARIS IFS in polarimetry mode allows characterization of these systems at wavelengths spanning the NIR J, H, and K bands ($1.1-2.4$ $\mu m$, $R\sim20$) and at angular separations as small as 0.04". By comparing the resulting images with forward-modeled scattered light or 3D radiative-transfer models, the likely origins of any observed features can be assessed. Utilization of swift optimization algorithms, such as differential evolution (DE), to identify model parameters that best reproduce the observations allows plausible disk geometries to be explored efficiently. The recent addition of CHARIS's unique integral field spectropolarimetry mode has further facilitated the study of planet-forming disks -- aiding in the confirmation of candidate protoplanets, the diagnosis of disk structures, and the characterization of dust grain populations. We summarize preliminary results for two young planet-forming disk systems based on observations with the novel integral field spectropolarimetry mode for SCExAO/CHARIS.