Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750

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Main Authors: Liu, Zhu, Ryu, Taeho, Goodwin, A. J., Rau, A., Homan, D., Krumpe, M., Merloni, A., Grotova, I., Anderson, G. E., Malyali, A., Miller-Jones, J. C. A.
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Published: 2024
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author Liu, Zhu
Ryu, Taeho
Goodwin, A. J.
Rau, A.
Homan, D.
Krumpe, M.
Merloni, A.
Grotova, I.
Anderson, G. E.
Malyali, A.
Miller-Jones, J. C. A.
author_facet Liu, Zhu
Ryu, Taeho
Goodwin, A. J.
Rau, A.
Homan, D.
Krumpe, M.
Merloni, A.
Grotova, I.
Anderson, G. E.
Malyali, A.
Miller-Jones, J. C. A.
contents In this letter, we present the results from further 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, making it one of the most promising repeating partial tidal disruption event (pTDE) candidates. More importantly, we also found rapid changes in the recurrence time $T_\text{recur}$ of the X-ray flares by modelling the long-term X-ray light curve of J0456-20. $T_\text{recur}$ 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 $T_\text{recur}$ evidenced from the latest three cycles. Our hydrodynamic simulations suggest that, in the repeating pTDE scenario, such rapid evolution of $T_\text{recur}$ could be reproduced if the original star is a $1~\mathrm{M}_\odot$ main-sequence star near the terminal age and loses nearly 80-90% of its mass during the initial encounter with a supermassive black hole (SMBH) of mass around $10^5~\mathrm{M}_\odot$. The inferred mass loss of 0.8-0.9 $\mathrm{M}_\odot$ is higher than the estimated value of around 0.13 $\mathrm{M}_\odot$ from observation, which could be explained if the radiation efficiency is low (i.e. $\ll0.1$). Our results indicate that repeating pTDEs could be effective tools to explore the dynamics around supermassive black holes beyond our own Galaxy.
format Preprint
id arxiv_https___arxiv_org_abs_2401_14091
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750
Liu, Zhu
Ryu, Taeho
Goodwin, A. J.
Rau, A.
Homan, D.
Krumpe, M.
Merloni, A.
Grotova, I.
Anderson, G. E.
Malyali, A.
Miller-Jones, J. C. A.
High Energy Astrophysical Phenomena
In this letter, we present the results from further 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, making it one of the most promising repeating partial tidal disruption event (pTDE) candidates. More importantly, we also found rapid changes in the recurrence time $T_\text{recur}$ of the X-ray flares by modelling the long-term X-ray light curve of J0456-20. $T_\text{recur}$ 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 $T_\text{recur}$ evidenced from the latest three cycles. Our hydrodynamic simulations suggest that, in the repeating pTDE scenario, such rapid evolution of $T_\text{recur}$ could be reproduced if the original star is a $1~\mathrm{M}_\odot$ main-sequence star near the terminal age and loses nearly 80-90% of its mass during the initial encounter with a supermassive black hole (SMBH) of mass around $10^5~\mathrm{M}_\odot$. The inferred mass loss of 0.8-0.9 $\mathrm{M}_\odot$ is higher than the estimated value of around 0.13 $\mathrm{M}_\odot$ from observation, which could be explained if the radiation efficiency is low (i.e. $\ll0.1$). Our results indicate that repeating pTDEs could be effective tools to explore the dynamics around supermassive black holes beyond our own Galaxy.
title Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2401.14091