Loose Ends for the Exomoon Candidate Host Kepler-1625b
| Autor: | Andrew W. Howard, David M. Kipping, Ruth Angus, Alex Teachey, Christopher J. Burke |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physics
Earth and Planetary Astrophysics (astro-ph.EP) Offset (computer science) 010504 meteorology & atmospheric sciences Stellar rotation Autocorrelation Exomoon FOS: Physical sciences Astronomy and Astrophysics Astrophysics Residual 01 natural sciences symbols.namesake Space and Planetary Science Planet Gaussian noise 0103 physical sciences symbols 010303 astronomy & astrophysics Gaussian process 0105 earth and related environmental sciences Astrophysics - Earth and Planetary Astrophysics |
| DOI: | 10.48550/arxiv.1904.11896 |
| Popis: | The claim of an exomoon candidate in the Kepler-1625b system has generated substantial discussion regarding possible alternative explanations for the purported signal. In this work we examine in detail these possibilities. First, the effect of more flexible trend models is explored and we show that sufficiently flexible models are capable of attenuating the signal, although this is an expected byproduct of invoking such models. We also explore trend models using X and Y centroid positions and show that there is no data-driven impetus to adopt such models over temporal ones. We quantify the probability that the 500 ppm moon-like dip could be caused by a Neptune-sized transiting planet to be < 0.75%. We show that neither autocorrelation, Gaussian processes nor a Lomb-Scargle periodogram are able to recover a stellar rotation period, demonstrating that K1625 is a quiet star with periodic behavior < 200 ppm. Through injection and recovery tests, we find that the star does not exhibit a tendency to introduce false-positive dip-like features above that of pure Gaussian noise. Finally, we address a recent re-analysis by Kreidberg et al (2019) and show that the difference in conclusions is not from differing systematics models but rather the reduction itself. We show that their reduction exhibits i) slightly higher intra-orbit and post-fit residual scatter, ii) $\simeq$ 900 ppm larger flux offset at the visit change, iii) $\simeq$ 2 times larger Y-centroid variations, and iv) $\simeq$ 3.5 times stronger flux-centroid correlation coefficient than the original analysis. These points could be explained by larger systematics in their reduction, potentially impacting their conclusions. 21 pages, 4 tables, 11 figures. Accepted for publication in The Astronomical Journal, January 2020 |
| Databáze: | OpenAIRE |
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