Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750
In this letter, we present the results from subsequent X-ray and UV observations of the nuclear transient eRASSt J045650.3-203750 (hereafter, J0456-20). We detected five repeating X-ray and UV flares from J0456-20, marking it as one of the most promising repeating partial tidal disruption event (pTD...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
| Published: |
2024
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| Online Access: | http://purl.org/au-research/grants/arc/DP200102471 http://hdl.handle.net/20.500.11937/96139 |
| Summary: | In this letter, we present the results from subsequent X-ray and UV observations of the nuclear transient eRASSt J045650.3-203750 (hereafter, J0456-20). We detected five repeating X-ray and UV flares from J0456-20, marking it as one of the most promising repeating partial tidal disruption event (pTDE) candidates. More importantly, we also found rapid changes in the recurrence time, Trecur, of the X-ray flares by modelling the long-term X-ray light curve of J0456-20. We found that Trecur first decreased rapidly from about 300 days to around 230 days. It continued to decrease to around 190 days with an indication of a constant Trecur, as evidenced by the latest three cycles. Our hydrodynamic simulations suggest that, in the repeating pTDE scenario, such a rapid evolution of Trecur could be reproduced if the original star is a 1 M⊙ main sequence star near the terminal age, losing nearly 80- 90% of its mass during the initial encounter with a supermassive black hole (SMBH) of a mass around 105 M⊙. The inferred mass loss of 0.8- 0.9 M⊙ is higher than the estimated value of around 0.13 M⊙ drawn from observations, which could be explained if the radiation efficiency is low (i.e. ≪0.1). Our results indicate that repeating pTDEs could be effective tools for exploring the dynamics around SMBHs beyond our own Galaxy. |
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