WASP-4 transit timing variation from a comprehensive set of 129 transits

• Published in: arXiv.org 2020-04
• Main Authors: Baluev, R V, Sokov, E N, Hoyer, S, Huitson, C, José A R S da Silva, Evans, P, Sokova, I A, Knight, C R, V Sh Shaidulin
• Format: Article
• Language: English
• Subjects: Decay rate; Extrasolar planets; Gas giant planets; Light curve; Nonlinear analysis; Q factors; Transit
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2004.09109

We homogeneously reanalyse \(124\) transit light curves for the WASP-4 b hot Jupiter. This set involved new observations secured in 2019 and nearly all observations mentioned in the literature, including high-accuracy GEMINI/GMOS transmission spectroscopy of 2011-2014 and TESS observations of 2018. The analysis confirmed a nonlinear TTV trend with \(P/|\dot P|\sim (17-30)\) Myr (1-sigma range), implying only half of the initial decay rate estimation. The trend significance is at least \(3.4\)-sigma in the agressively conservative treatment. Possible radial acceleration due to unseen companions is not revealed in Doppler data covering seven years 2007-2014, and radial acceleration of \(-15\) m s\(^{-1}\)yr\(^{-1}\) reported in a recent preprint by another team is not confirmed. If present, it is a very nonlinear RV variation. Assuming that the entire TTV is tidal in nature, the tidal quality factor \(Q_\star'\sim (4.5-8.5)\cdot 10^4\) does not reveal a convincing disagreement with available theory predictions.