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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2506.09603 |
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| _version_ | 1866909646029062144 |
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| author | Cao, Z. Jonker, P. G. Wen, S. Stone, N. C. Zabludoff, A. I. |
| author_facet | Cao, Z. Jonker, P. G. Wen, S. Stone, N. C. Zabludoff, A. I. |
| contents | We fit the evolving X-ray spectra of the variable and fading source 2XMM J123103.2+110648 (J1231), which is an intermediate-mass black hole (IMBH) candidate. Recent X-ray timing studies have proposed that J1231's quasi-periodic oscillation (QPO) observed at the peak of its X-ray lightcurve is a variant of the quasi-periodic eruptions (QPEs) observed in other sources. Here, we fit X-ray spectra from XMM-Newton, Swift, and Chandra using a slim disc model for the black hole's accretion disc, obtaining a best-fit black hole mass of ($6\pm3)\times10^{4}$ $M_\odot$ and spin of $>0.6$ at 2$σ$ confidence. This mass is consistent with past estimates, supporting the IMBH interpretation, and the spin measurement is new. Yet the nature of J1231 remains uncertain: its long-term variability (decade-long continuum evolution) could signal a tidal disruption event or active galactic nuclear variability. We find that the spectral evolution within the first three years after the source's detection can be well explained by either a varying disc accretion rate $\dot m$ or a varying disc inclination $θ$. Meanwhile, we find that during the short-term variability (the QPO with a ~3.8hr period), each oscillation does not show the "hard-rise-soft-decay" typical of QPEs. We fit the average spectrum at the QPO lightcurve maxima and the average spectrum at its minima, finding that the spectral difference is well explained by $\dot m$ decreasing from peaks to valleys if $θ<30^{\circ}$ and constant between all data epochs. This result suggests that the short-term QPO behaviour might also be driven by a varying disc $\dot m$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_09603 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The intermediate-mass black hole 2XMM J123103.2+110648: a varying disc accretion rate during possible X-ray quasi-periodic eruptions? Cao, Z. Jonker, P. G. Wen, S. Stone, N. C. Zabludoff, A. I. High Energy Astrophysical Phenomena We fit the evolving X-ray spectra of the variable and fading source 2XMM J123103.2+110648 (J1231), which is an intermediate-mass black hole (IMBH) candidate. Recent X-ray timing studies have proposed that J1231's quasi-periodic oscillation (QPO) observed at the peak of its X-ray lightcurve is a variant of the quasi-periodic eruptions (QPEs) observed in other sources. Here, we fit X-ray spectra from XMM-Newton, Swift, and Chandra using a slim disc model for the black hole's accretion disc, obtaining a best-fit black hole mass of ($6\pm3)\times10^{4}$ $M_\odot$ and spin of $>0.6$ at 2$σ$ confidence. This mass is consistent with past estimates, supporting the IMBH interpretation, and the spin measurement is new. Yet the nature of J1231 remains uncertain: its long-term variability (decade-long continuum evolution) could signal a tidal disruption event or active galactic nuclear variability. We find that the spectral evolution within the first three years after the source's detection can be well explained by either a varying disc accretion rate $\dot m$ or a varying disc inclination $θ$. Meanwhile, we find that during the short-term variability (the QPO with a ~3.8hr period), each oscillation does not show the "hard-rise-soft-decay" typical of QPEs. We fit the average spectrum at the QPO lightcurve maxima and the average spectrum at its minima, finding that the spectral difference is well explained by $\dot m$ decreasing from peaks to valleys if $θ<30^{\circ}$ and constant between all data epochs. This result suggests that the short-term QPO behaviour might also be driven by a varying disc $\dot m$. |
| title | The intermediate-mass black hole 2XMM J123103.2+110648: a varying disc accretion rate during possible X-ray quasi-periodic eruptions? |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2506.09603 |