Black hole mass and optical radiation mechanism of the tidal disruption event AT 2023clx

We present the optical light curves of the tidal disruption event (TDE) AT 2023clx in the declining phase, observed with Mephisto. Combining our light curve with the ASAS-SN and ATLAS data in the rising phase, and fitting the composite multi-band light curves with MOSFiT, we estimate black hole mass of AT 2023clx is between ${10}^{5.67}$–${10}^{5.82}{M}_{\odot }$. This event may be caused by either a full disruption of a $0.1M_{\odot }$ star, or a partial disruption of a $0.99M_{\odot }$ star, depending on the data adopted for the rising phase. Based on those fit results and the non-detection of soft X-ray photons in the first 90 days, we propose that the observed optical radiation is powered by stream-stream collision. We speculate that the soft X-ray photons may gradually emerge in 100–600 days after the optical peak, when the debris is fully circularized into a compact accretion disk.