Detecting and analyzing exoplanets at lower separations using high resolution integral field spectroscopy

Detecting exoplanets through direct imaging at lower angular separations, where more planets are expected to be, is limited by the variability of the stellar point spread function. Integral field spectrographs like OSIRIS at the Keck Observatory can leverage high spectral resolution to search for new planets at smaller separations (<0.3”) by detecting their distinct spectral signature compared to the diffracted starlight. We present an open-source data analysis pipeline called the Broad Repository for Exoplanet Analysis, Detection, and Spectroscopy (breads), which can use high spectral resolution data from existing and in-development instruments.

We used this code to search for planets around 10 targets in the Ophiuchus and Taurus star-forming regions and present our preliminary results here. We use this pathfinder survey with Keck/OSIRIS to demonstrate this technique and compare the final sensitivities to other classical imaging techniques. Our work will be applicable to future integral field spectrographs like NIRSpec on the James Webb Space Telescope and other first light instruments on the future Extremely Large Telescope, which are poised to become the next generation of exoplanet detection facilities.

Our code is based on a forward-modeling framework, which is statistically more accurate than classical cross-correlation techniques. breads includes a built-in optimization and analytical marginalization of linear parameters in the forward model, therefore limiting the number of parameters to be explored by the posterior sampling method. We allow users to select forward models, parameters to detect and analyze, and fitting methods like Markov Chain Monte Carlo sampling, grid optimization, and gradient descent. breads provides a flexible framework to retrieve radial velocity, spin, and atmospheric parameters of high-contrast companions.