Reverberation Evidence for Stream Collision and Delayed Disk Formation in Tidal Disruption Events

作者：Hengxiao Guo, Jingbo 静泊 Sun 孙, Shuang‐Liang Li, Yan-Fei Jiang, Tinggui Wang, De-Fu Bu, Ning Jiang, Yanan Wang, Yuhan Yao, Rong-Feng Shen, Minfeng Gu, Mouyuan Sun · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/ada274 · 被引用次数：9 · 研究领域：Seismic Waves and Analysis、Astrophysics and Cosmic Phenomena、Radio Astronomy Observations and Technology

Abstract When a star passes through the tidal disruption radius of a massive black hole (BH), it can be torn apart by the tidal force of the BH, known as the tidal disruption event (TDE). Since the observed UV/optical luminosity significantly exceeds the predictions of the compact disk model in classical TDE theory, two competing models, stream collision and envelope reprocessing, have been proposed to address this discrepancy. To distinguish between these models, we investigated the continuum reverberation behaviors for ~30 TDEs with high-quality multiband light curves. We found that over half of them exhibit a positive lag by a few days in UV/optical bands, indicating that their inferred sizes are significantly larger than the envelope sizes in reprocessing. Moreover, X-ray emissions are not only significantly delayed relative to the primary UV/optical peak but also lag behind the rebrightening bump by up to several tens of days, completely different from the X-ray illumination reprocessing. Additionally, the anticorrelated UV−optical continuum in ASASSN-15lh further disfavors the reprocessing scenario. In contrast, the model of stream collisions, combined with delayed accretion disk formation, can provide a unified explanation for the diverse TDE observations, e.g., the optical/X-ray population and the frequently observed rebrightening bump. This model describes a unification scheme wherein the UV/optical emission originates from stream collisions during the early stage of...