Kavli Affiliate: Bruce Macintosh
| First 5 Authors: Shubh Agrawal, Jean-Baptiste Ruffio, Quinn M. Konopacky, Bruce Macintosh, Dimitri Mawet
| Summary:
While radial velocity surveys have demonstrated that the population of gas
giants peaks around $3~text{au}$, the most recent high-contrast imaging
surveys have only been sensitive to planets beyond $sim~10~text{au}$.
Sensitivity at small angular separations from stars is currently limited by the
variability of the point spread function. We demonstrate how
moderate-resolution integral field spectrographs can detect planets at smaller
separations ($lesssim~0.3$ arcseconds) by detecting the distinct spectral
signature of planets compared to the host star. Using OSIRIS ($R$ $approx$
4000) at the W. M. Keck Observatory, we present the results of a planet search
via this methodology around 20 young targets in the Ophiuchus and Taurus
star-forming regions. We show that OSIRIS can outperform high-contrast
coronagraphic instruments equipped with extreme adaptive optics and
non-redundant masking in the $0.05-0.3$ arcsecond regime. As a proof of
concept, we present the $34sigma$ detection of a high-contrast M dwarf
companion at $approx0.1$" with a flux ratio of $approx0.92%$ around the
field F2 star HD 148352. We developed an open-source Python package, breads,
for the analysis of moderate-resolution integral field spectroscopy data in
which the planet and the host star signal are jointly modeled. The diffracted
starlight continuum is forward-modeled using a spline model, which removes the
need for prior high-pass filtering or continuum normalization. The code allows
for analytic marginalization of linear hyperparameters, simplifying posterior
sampling of other parameters (e.g., radial velocity, effective temperature).
This technique could prove very powerful when applied to integral field
spectrographs like NIRSpec on the JWST and other upcoming first-light
instruments on the future Extremely Large Telescopes.
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