http://arxiv.org/abs/2203.13290
The exomoon candidate Kepler-1708 b-i was recently reported using two transits of Kepler data. Supported by a 1% false-positive probability, the candidate is promising but requires follow-up observations to confirm/reject its validity. In this short paper, we calculate the detectability of the exomoon candidate’s transit in the next window (March 2023) using the WFC3 instrument aboard the Hubble Space Telescope (HST). Using realistic noise estimates, accounting for the visit-long trends, and propagating the model posteriors derived using the Kepler data, we perform 50 injection-recovery trials with Bayesian model selection. Defining a detection criterion that the moon transit must be detected to a Bayes factor exceeding 10 using HST alone, only 18 of the injections were recovered, yielding a true-positive probability (TPP) of $(36\pm7)$%. Despite HST’s superior aperture to Kepler, both instrumental systematics and the compactness of the candidate exomoon’s orbit typically obfuscate a strong detection. Although the noise properties of the James Webb Space Telescope (JWST) have not yet been characterized in flight, we estimate the signal would be easily recovered using NIRSpec operating in its Bright Object Time Series mode.
B. Cassese and D. Kipping
Mon, 28 Mar 22
39/50
Comments: 5 pages, 2 figures, submitted to MNRAS
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