Detectability of exomoons with transit technique from space-based telescopes

Abstract

There are numerous searches for exomoons, moons of exoplanets. The Transit Timing Variation (TTV) and Transit Duration Variation (TDV) techniques are two of the most effective methods for detecting exomoons. Due to the exomoon component, the TTV and TDV signals have distinctive characteristics based on the moon phase when the moon transits within the planetary disc during primary exomoon transit and secondary exomoon transit. This study uses TTV and TDV techniques to search for exomoon signals in exoplanetary systems. We intend to study the TTV and TDV signals of the star-planet-moon models by applying photometric precision of the TESS telescope and comparing the results of fitting TTV and TDV with and without cutting the extraordinary features. Cutting the unusual features in TTV and TDV signals will produce more accurate signals finding for an exomoon than the fitting without cutting the distinct features. The moon period and moon semi-major axis are crucial properties. Small values of the moon period and moon semi-major axis will give results that are closer to actual values if TTV and TDV are fitted with cutting the unique characteristics rather than the fitting without cutting in contrast to the large values of the moon period and the moon's semi-major axis. IMPLICATION OF THESIS: There are several initiatives to find an exomoon. Exomoons have not yet been confirmed. It may be possible to detect an exomoon by analyzing Transit Timing Variation (TTV) and Transit Duration Variation (TDV). The TTV and TDV signals of an exoplanetary system with a moon have peculiar characteristics due to the exomoon's existence. This results in the shape of TTV and TDV signals deviating from theory. The theory explains that the TTV and TDV signals of an exoplanetary system with an exomoon present a sine function characteristic. Previous work suggests that TTV and TDV signals have unique features. The TTV and TDV vary with moon phase evolution in sine function, but two smaller amplitudes are presented over the whole range of moon phases when in moon transits within the planetary disc during primary and secondary exomoon transits. Fitting the TTV and TDV with distinctive features is nonsensical. As expected, the results of this study indicate that removing the peculiar characteristics before fitting the TTV and TDV will result in a close approximation of the theoretical value. We compared the results of fitting TTV and TDV with and without the anomalous features to ensure that removing them would yield a better outcome. The result obtained by deleting the uncommon features is closer to the value from the models of an exoplanetary system with an exomoon that we generated than the result obtained by not removing the strange features. Therefore, we conclude that by eliminating the anomalous features beforehand to fit the TTV and TDV will increase the possibility of detecting an exomoon.