Impact crater counts on the Saturnian satellites are a key element for estimating their surface ages and placing constraints on their impactor population. The Cassini mission radar observations allowed crater counts to be made on the surface of Titan, revealing an unexpected scarcity of impact craters that show high levels of degradation. Following previous studies on impact cratering rates on the Saturnian satellites, we modeled the cratering process on Titan to constrain its surface chronology and to assess the role of centaur objects as its main impactors. A theoretical model previously developed was used to calculate the crater production on Titan, considering the centaur objects as the main impactors and including two different slopes for the size-frequency distribution (SFD) of the smaller members of their source population. A simple model for the atmospheric shielding effects is considered within the cratering process and our results are then compared with other synthetic crater distributions and updated observational crater counts. This comparison is then used to compute Titan's crater retention age for each crater diameter. The cumulative crater distribution produced by the SFD with a differential index of $s_2 = 3.5$ is found to consistently predict large craters (D > 50 km) on the surface of Titan, while it overestimates the number of smaller craters. As both the modeled and observed distributions flatten for craters with $D \lesssim 25 $ km due to atmospheric shielding, the difference between them can be considered as a proxy for the scale to which erosion processes have acted on the surface of Titan throughout the Solar System age. Our results for the surface chronology of Titan indicate that craters with D > 50 km can prevail over the Solar System age, whereas smaller craters may be completely obliterated due to erosion processes acting globally.
A youthful Titan implied by improved impact simulations
Massachusetts Institute of Technology（麻省理工学院）；Purdue University（普渡大学）；The Planetary Science Institute（行星科学研究所）；The University of Western Ontario（韦仕敦大学）
Geneva Observatory, University of Geneva（日内瓦天文台，日内瓦大学）；Earth Life Science Institute, Tokyo Institute of Technology（地球生命研究所，东京工业大学）；Centre for Planetary Habitability, Department of Geosciences, University of Oslo（行星宜居性中心，地质科学系，奥斯陆大学）；Southwest Research Institute（西南研究所）；Konkoly Observatory, HUN-REN CSFK, MTA Centre of Excellence（孔科利天文台，匈牙利研究与创新网络科学院天体物理研究中心，MTA卓越中心）
