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 µm 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 ≈ 4.4 mag, W2 ≈ 3.9 mag), we find that NIRISS AMI and KPI reach contrasts of ∼ 7-8 mag at ∼ 70 mas and ∼ 9 mag at ∼ 200 mas. Beyond ∼ 250 mas, NIRCam coronagraphy reaches deeper contrasts of ∼ 13 mag at ∼ 500 mas and ∼ 15 mag at ∼ 2 arcsec. While the bar mask performs ∼ 1 mag better than the round mask at small angular separations ≲ 0.75 arcsec, it is the other way around at large angular separations ≳ 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 ∼ 10 times better at large separations than the best ground-based instruments operating at similar wavelengths despite its \u3e 2 times smaller collecting area

Improved Orbital Constraints and Hα\alpha Photometric Monitoring of the Directly Imaged Protoplanet Analog HD 142527 B

Companions embedded in the cavities of transitional circumstellar disks have been observed to exhibit excess luminosity at H$\alpha$, an indication that they are actively accreting. We report 5 years (2013-2018) of monitoring of the position and H$\alpha$ excess luminosity of the embedded, accreting low-mass stellar companion HD 142527 B from the MagAO/VisAO instrument. We use pyklip, a python implementation of the Karhounen-Loeve Image Processing algorithm, to detect the companion. Using pyklip forward modeling, we constrain the relative astrometry to $1-2 \mathrm{mas}$ precision and achieve sufficient photometric precision ($\pm0.2 \mathrm{mag}, 3\%$ error) to detect changes in the H$\alpha$ contrast of the companion over time. In order to accurately determine the relative astrometry of the companion, we conduct an astrometric calibration of the MagAO/VisAO camera against 20 years of Keck/NIRC2 images of the Trapezium cluster. We demonstrate agreement of our VisAO astrometry with other published positions for HD 142527 B, and use orbitize! to generate a posterior distribution of orbits fit to the relative astrometry of HD 142527 B. Our data suggest that the companion is close to periastron passage, on an orbit significantly misinclined with respect to both the wide circumbinary disk and the recently observed inner disk encircling HD 142527 A. We translate observed H-alpha contrasts for HD 142527 B into mass accretion rate estimates on the order of $4-9\times10^{-10} \mathrm{M_\odot}\mathrm{yr}^{-1}$. Photometric variation in the H-alpha excess of the companion suggests that the accretion rate onto the companion is variable. This work represents a significant step towards observing accretion-driven variability onto protoplanets, such as PDS 70 b\&c.Comment: Accepted to the Astronomical Journal. 32 pages, 16 figures, 8 tables, 4 appendice

The Giant Accreting Protoplanet Survey (GAPlanetS) -- Results from a Six Year Campaign to Image Accreting Protoplanets

Accreting protoplanets represent a window into planet formation processes. We report H{\alpha} differential imaging results from the deepest and most comprehensive accreting protoplanet survey to date, acquired with the Magellan Adaptive Optics (MagAO) system's VisAO camera. The fourteen transitional disks targeted are ideal candidates for protoplanet discovery due to their wide, heavily depleted central cavities, wealth of non-axisymmetric circumstellar disk features evocative of ongoing planet formation, and ongoing stellar accretion. To address the twin challenges of morphological complexity in the target systems and PSF instability, we develop novel approaches for frame selection and optimization of the Karhounen-Loeve Image Processing algorithm pyKLIP. We detect one new candidate protoplanet, CS Cha "c", at a separation of 75mas and a {\Delta}mag of 5.1 and robustly recover the HD142527 B and HD100453 B low mass stellar companions across multiple epochs. Though we cannot rule out a substantial scattered light contribution to its emission, we also recover LkCa 15 b. Its presence inside of the cleared disk cavity and consistency with a forward-modeled point source suggest that it remains a viable protoplanet candidate. The protoplanet PDS 70 c was marginally recovered under our conservative general methodology. However, through targeted optimization in H{\alpha} imagery, we tentatively recover PDS 70 c in three epochs and PDS 70 b in one epoch. Of the many other previously-reported companions and companion candidates around objects in the sample, we do not recover any additional robust candidates. However, lack of recovery at moderate H{\alpha} contrast does not rule out the presence of protoplanets at these locations, and we report limiting H{\alpha} contrasts in such cases.Comment: Accepted for publication in A

Detection of Carbon Monoxide in the Atmosphere of WASP-39b Applying Standard Cross-Correlation Techniques to JWST NIRSpec G395H Data

Carbon monoxide was recently reported in the atmosphere of the hot Jupiter WASP-39b using the NIRSpec PRISM transit observation of this planet, collected as part of the JWST Transiting Exoplanet Community Early Release Science (JTEC ERS) Program. This detection, however, could not be confidently confirmed in the initial analysis of the higher resolution observations with NIRSpec G395H disperser. Here we confirm the detection of CO in the atmosphere of WASP-39b using the NIRSpec G395H data and cross-correlation techniques. We do this by searching for the CO signal in the unbinned transmission spectrum of the planet between 4.6 and 5.0 $\mu$m, where the contribution of CO is expected to be higher than that of other anticipated molecules in the planet's atmosphere. Our search results in a detection of CO with a cross-correlation function (CCF) significance of $6.6 \sigma$ when using a template with only ${\rm ^{12}C^{16}O}$ lines. The CCF significance of the CO signal increases to $7.5 \sigma$ when including in the template lines from additional CO isotopologues, with the largest contribution being from ${\rm ^{13}C^{16}O}$. Our results highlight how cross-correlation techniques can be a powerful tool for unveiling the chemical composition of exoplanetary atmospheres from medium-resolution transmission spectra, including the detection of isotopologues.Comment: Accepted for publication in The Astrophysical Journal Letter

The Giant Accreting Protoplanet Survey (GAPlanetS): Optimization Techniques for Robust Detections of Protoplanets

High-contrast imaging has afforded astronomers the opportunity to study light directly emitted by adolescent (tens of megayears) and “proto” (<10 Myr) planets still undergoing formation. Direct detection of these planets is enabled by empirical point-spread function (PSF) modeling and removal algorithms. The computational intensity of such algorithms, as well as their multiplicity of tunable input parameters, has led to the prevalence of ad hoc optimization approaches to high-contrast imaging results. In this work, we present a new, systematic approach to optimization vetted using data of the high-contrast stellar companion HD 142527 B from the Magellan Adaptive Optics Giant Accreting Protoplanet Survey (GAPlanetS). More specifically, we present a grid search technique designed to explore three influential parameters of the PSF subtraction algorithm pyKLIP : annuli, movement, and KL modes. We consider multiple metrics for postprocessed image quality in order to optimally recover at H α (656 nm) synthetic planets injected into contemporaneous continuum (643 nm) images. These metrics include peak (single-pixel) signal-to-noise ratio (S/N), average (multipixel average) S/N, 5 σ contrast, and false-positive fraction. We apply continuum-optimized KLIP reduction parameters to six H α direct detections of the low-mass stellar companion HD 142527 B and recover the companion at a range of separations. Relative to a single-informed, nonoptimized set of KLIP parameters applied to all data sets uniformly, our multimetric grid search optimization led to improvements in companion S/N of up to 1.2 σ , with an average improvement of 0.6 σ . Since many direct imaging detections lie close to the canonical 5 σ threshold, even such modest improvements may result in higher yields in future imaging surveys

High Tide or Rip-Tide? GJ 486b JWST Transits with NIRSpec G395H - Supplementary Material, v2

Supplementary material for 'High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations' by Moran &amp; Stevenson et al., ApJL (2023). This repository contains four categories of data products: White light curves — White light curves produced for Visit 1 and 2, for detectors NRS1 and NRS2 via the open-source codes Eureka! and Tiberius Transmission spectra — Reduced transmission spectra from three data reduction codes (Eureka!, FIREFLy, and Tiberius) for both G395H visits. Stellar spectra and models — Flux calibrated observed stellar spectra of GJ 486 from each G395H visit, along with best-fit PHOENIX stellar models. Atmospheric models — Atmospheric forward models used to interpret the data, produced from the open source PICASO and CHIMERA codes. For any additional data requests or questions, please contact: [email protected] or [email protected]

High Tide or Rip-Tide? GJ 486b JWST Transits with NIRSpec G395H - Supplementary Material, v3

Supplementary material for 'High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations' by Moran &amp; Stevenson et al., ApJL (2023). This repository contains four categories of data products: White light curves — White light curves produced for Visit 1 and 2, for detectors NRS1 and NRS2 via the FIREFLy pipeline and the open-source codes Eureka! and Tiberius Transmission spectra — Reduced transmission spectra from three data reduction codes (Eureka!, FIREFLy, and Tiberius) for both G395H visits. Stellar spectra and models — Flux calibrated observed stellar spectra of GJ 486 from each G395H visit, along with best-fit PHOENIX stellar models. Atmospheric models — Atmospheric forward models used to interpret the data, produced from the open source PICASO and CHIMERA codes. For any additional data requests or questions, please contact: [email protected] or [email protected]

High Tide or Rip-Tide? GJ 486b JWST Transits with NIRSpec G395H - Supplementary Material, v1

Supplementary material for 'High Tide or Riptide on the Cosmic Shoreline? A Water-rich Atmosphere or Stellar Contamination for the Warm Super-Earth GJ 486b from JWST Observations' by Moran &amp; Stevenson et al., ApJL (2023). This repository contains four categories of data products: White light curves — White light curves produced for Visit 1 and 2, for detectors NRS1 and NRS2 via the open-source code Eureka! Transmission spectra — Reduced transmission spectra from three data reduction codes (Eureka!, FIREFLy, and Tiberius) for both G395H visits. Stellar spectra and models — Flux calibrated observed stellar spectra of GJ 486 from each G395H visit, along with best-fit PHOENIX stellar models. Atmospheric models — Atmospheric forward models used to interpret the data, produced from the open source PICASO and CHIMERA codes. For any additional data requests or questions, please contact: [email protected] or [email protected]

Detection of Carbon Monoxide in the Atmosphere of WASP-39b Applying Standard Cross-correlation Techniques to JWST NIRSpec G395H Data

Carbon monoxide was recently reported in the atmosphere of the hot Jupiter WASP-39b using the NIRSpec PRISM transit observation of this planet, collected as part of the JWST Transiting Exoplanet Community Early Release Science Program. This detection, however, could not be confidently confirmed in the initial analysis of the higher-resolution observations with NIRSpec G395H disperser. Here we confirm the detection of CO in the atmosphere of WASP-39b using the NIRSpec G395H data and cross-correlation techniques. We do this by searching for the CO signal in the unbinned transmission spectrum of the planet between 4.6 and 5.0 μ m, where the contribution of CO is expected to be higher than that of other anticipated molecules in the planet’s atmosphere. Our search results in a detection of CO with a cross-correlation function (CCF) significance of 6.6 σ when using a template with only ^12 C ^16 O lines. The CCF significance of the CO signal increases to 7.5 σ when including in the template lines from additional CO isotopologues, with the largest contribution being from ^13 C ^16 O. Our results highlight how cross-correlation techniques can be a powerful tool for unveiling the chemical composition of exoplanetary atmospheres from medium-resolution transmission spectra, including the detection of isotopologues