A Central TDE Candidate Detected through Spectroscopic Continuum Emission Properties in an SDSS Blue Quasar

Abstract In this paper, properties of spectroscopic continuum emissions are considered to detect potential tidal disruption event (TDE) candidates among Sloan Digital Sky Survey (SDSS) quasars. After considering the simple blackbody photosphere model applied to describe quasar continuum emissions with parameters of blackbody temperature T BB and blackbody radius R BB , SDSS quasars and reported optical TDEs occupy distinct regions in the space of T BB and R BB . Then, through the dependence of R BB on T BB for SDSS quasars, 402 outliers in the SDSS Stripe 82 region can be collected. Among the 402 outliers, SDSS J2308 at z = 1.16 is mainly considered, due to its SDSS spectrum observed around the peak brightness of the light curves. With the 7.2 yr long light curves described by the theoretical TDE model, the determined T BB and R BB through its spectroscopic continuum emissions are consistent with the values determined by the TDE model, to support the central TDE. Moreover, considering simulated results on continuum emissions of SDSS quasars around z ∼ 1.16, it can be confirmed at a confidence level higher than 4 σ that the continuum emissions of SDSS J2308 are not related to normal quasars. Furthermore, through the simulated results by the accepted continuous autoregressive process to trace intrinsic active galactic nucleus variability, the confidence level higher than 3 σ can be confirmed that the long-term light curves of SDSS J2308 are related to a central TDE. The jointed probabilities through both spectroscopic and photometric simulations, the confidence level higher than 5 σ can be confirmed to support the central TDE in SDSS J2308.