Performance of near-infrared high-contrast imaging methods with JWST from commissioning

The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3-5 mu m regime based on data taken during the instrument commissioning. Firstly, we introduce custom tools to simulate, reduce, and analyze JWST NIRCam and MIRI coronagraphy data and use these tools to extract companion detection limits from on-sky NIRCam round and bar mask coronagraphy observations. Secondly, we present on-sky JWST NIRISS aperture masking interferometry (AMI) and kernel phase imaging (KPI) observations from which we extract companion detection limits using the publicly available fouriever tool. Scaled to a total integration time of one hour and a target of the brightness of AB Dor (W1 approximate to 4.4 mag, W2 approximate to 3.9 mag), we find that NIRISS AMI and KPI reach contrasts of similar to 7-8 mag at similar to 70 mas and similar to 9 mag at similar to 200 mas. Beyond similar to 250 mas, NIRCam coronagraphy reaches deeper contrasts of similar to 13 mag at similar to 500 mas and similar to 15 mag at similar to 2 arcsec. While the bar mask performs similar to 1 mag better than the round mask at small angular separations less than or similar to 0.75 arcsec, it is the other way around at large angular separations greater than or similar to 1.5 arcsec. Moreover, the round mask gives access to the full 360 deg field-of-view which is beneficial for the search of new companions. We conclude that already during the instrument commissioning, JWST high-contrast imaging in the L- and M-bands performs close to its predicted limits and is a factor of similar to 10 times better at large separations than the best ground-based instruments operating at similar wavelengths despite its > 2 times smaller collecting area.

Automated summary

The James Webb Space Telescope (JWST) will revolutionize high-contrast imaging in the mid-infrared, allowing for direct detection of Saturn-mass planets and characterization of substellar companions. Through simulation and analysis of observational data, researchers have found that JWST performs close to predicted limits in L- and M-bands, surpassing ground-based instruments by a factor of 10 at larger separations.