Inefficient Circularization, Delayed Stream-Disk Interaction and Reprocessing: A Five-Stage Model for the Intermediate-Mass Black Hole Tidal Disruption Event EP240222a
Authors
Wenkai Li, Ning Jiang, Tinggui Wang, Rongfeng Shen, Erlin Qiao, Lixin Dai, Di Luo, Dongyue Li, Chichuan Jin, Jiazheng Zhu
Categories
Abstract
EP240222a is the first intermediate-mass black hole (IMBH) tidal disruption event (TDE) captured in real-time with multi-wavelength observations and spectroscopic confirmation. However, its light curves deviate substantially from previous theoretical expectations. Motivated by these unique features, we have developed a novel model that successfully reproduces its peculiar evolution. Our model delineates five stages: (1) Initial Stage of inefficient circularization; (2) Slow-Rising Stage with a faint X-ray precursor disk fed by successive self-crossings; (3) Fast-Rising Stage, where delayed stream-disk interaction at momentum flux matching drives a sharp luminosity rise; (4) Plateau Stage with super-Eddington accretion, outflow, reprocessing, and a clear polar line-of-sight; and (5) Decline Stage of sub-Eddington accretion and ongoing reprocessing. Our fit indicates the disruption of a $M_* \approx 0.4~M_\odot$ main-sequence (MS) star with a penetration factor $β\approx 1.0$. Our model, which incorporates key TDE processes, establishes EP240222a-like light curves as typical IMBH-TDE signatures. The distinctive identifier is a slow rise in X-rays and a corresponding slow rise/quasi-plateau in the UV/optical, followed by a brighter, super-Eddington plateau in both bands, though other forms exist, such as the rapid rise from white dwarf (WD) disruptions over minutes to days.
Inefficient Circularization, Delayed Stream-Disk Interaction and Reprocessing: A Five-Stage Model for the Intermediate-Mass Black Hole Tidal Disruption Event EP240222a
Categories
Abstract
EP240222a is the first intermediate-mass black hole (IMBH) tidal disruption event (TDE) captured in real-time with multi-wavelength observations and spectroscopic confirmation. However, its light curves deviate substantially from previous theoretical expectations. Motivated by these unique features, we have developed a novel model that successfully reproduces its peculiar evolution. Our model delineates five stages: (1) Initial Stage of inefficient circularization; (2) Slow-Rising Stage with a faint X-ray precursor disk fed by successive self-crossings; (3) Fast-Rising Stage, where delayed stream-disk interaction at momentum flux matching drives a sharp luminosity rise; (4) Plateau Stage with super-Eddington accretion, outflow, reprocessing, and a clear polar line-of-sight; and (5) Decline Stage of sub-Eddington accretion and ongoing reprocessing. Our fit indicates the disruption of a $M_* \approx 0.4~M_\odot$ main-sequence (MS) star with a penetration factor $β\approx 1.0$. Our model, which incorporates key TDE processes, establishes EP240222a-like light curves as typical IMBH-TDE signatures. The distinctive identifier is a slow rise in X-rays and a corresponding slow rise/quasi-plateau in the UV/optical, followed by a brighter, super-Eddington plateau in both bands, though other forms exist, such as the rapid rise from white dwarf (WD) disruptions over minutes to days.
Authors
Wenkai Li, Ning Jiang, Tinggui Wang et al. (+7 more)
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