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arXiv · 2603.22100

The full evolution of the type-C QPO in MAXI J1348-630 revealed by Insight-HXMT

X. -L. Wang·Z. Yan·F. -G. Xie·J. -F. Wang·Y. -X. Li·Z. -Y. Liu·R. -Y. Ma
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Abstract

Based on abundant data from Insight-HXMT, we conducted a detailed analysis of type-C quasi-periodic oscillations (QPOs) in the black hole X-ray binary MAXI J1348-630. Type-C QPOs were intensively detected over a broad energy band, with frequencies ranging from 0.24 to 10.3 Hz, and several new evolutionary features were identified. First, although type-C QPOs reappear intermittently, they show a stable characteristic frequency around 7 Hz. This implies a characteristic spatial scale for the QPO emission region, despite large variations in outburst intensity. Second, from the hard state to the hard-intermediate state, type-C QPOs display a harder fractional rms spectrum, with the rms peak shifting toward high energies (>20 keV) and an amplitude exceeding 10 %. This hard rms spectrum favors a high-energy origin for type-C QPOs. The spectral hardening occurs simultaneously with the weakening of the compact jet, suggesting a physical connection between these two processes. Finally, we observed hysteresis in the QPO frequency-flux relation, with the hysteresis loop evolving in opposite directions between the main and mini-outbursts. This offers a new perspective on the physical differences between the two outburst types, which may arise from variations in initial magnetic field conditions.

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X. -L. Wang, Z. Yan, F. -G. Xie, J. -F. Wang, Y. -X. Li, Z. -Y. Liu, R. -Y. Ma. 2026-03-23. The full evolution of the type-C QPO in MAXI J1348-630 revealed by Insight-HXMT. https://doi.org/10.1051/0004-6361/202558220

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