标题： 活跃且强劲：eRO-QPE2在3.5年间的稳定X射线准周期性爆发 显示英文标题

标题： Alive and Strongly Kicking: Stable X-ray Quasi-Periodic Eruptions from eRO-QPE2 over 3.5 Years

摘要： 准周期性爆发（QPE）是从星系核反复发出的软X射线爆发。它们的物理起源目前仍在争论之中，模型通常涉及围绕大质量黑洞或盘不稳定性运行的天体。本文介绍了我们对QPE源eRO-QPE2在3.5年期间的时间和光谱演化进行的研究和分析。我们发现eRO-QPE2：1）在整个3.5年的爆发峰值亮度、爆发温度、宁静状态温度和宁静状态亮度上表现出显著的稳定性；2）平均爆发重复时间为2.35小时，在3.5年内有（$\sim$2$\sigma$）的边缘证据表明减少了$0.1$小时；3）在2020年8月的复发时间出现了长短期变化，但这一模式在随后的所有观测中均未出现。其峰值爆发亮度和宁静状态的稳定性明显不同于之前追踪的三个QPE（GSN069、eRO-QPE1、eRO-QPE3），这些系统在相同的时间范围内显示出爆发和宁静状态流量的下降。由于eRO-QPE2的平均复发时间为2.4小时，而GSN-069为9小时，eRO-QPE1为16小时，eRO-QPE3为20小时，因此其稳定性更加显著，即在这3.5年的观测中，该系统的循环次数是其他系统的4到8倍。我们讨论了这些观测结果在一些提出的极端质量比旋进（EMRI）模型中的意义。 显示英文摘要

摘要： Quasi-periodic eruptions (QPEs) are recurring bursts of soft X-rays from the nuclei of galaxies. Their physical origin is currently a subject of debate, with models typically invoking an orbiter around a massive black hole or disk instabilities. Here we present and analyze the temporal and spectral evolution of the QPE source eRO-QPE2 over 3.5 years. We find that eRO-QPE2 1) is remarkably stable over the entire 3.5-year temporal baseline in its eruption peak luminosity, eruption temperature, quiescent temperature, and quiescent luminosity, 2) has a stable mean eruption recurrence time of 2.35 hours, with marginal ($\sim$2$\sigma$) evidence for a $0.1$ hour reduction over the 3.5 yr period, and 3) has a long-short variation in its recurrence time in August 2020, but this pattern is absent from all subsequent observations. The stability of its peak eruption luminosity and that of the quiescent state are notably dissimilar from three previously tracked QPEs (GSN069, eRO-QPE1, eRO-QPE3), which show declines in eruption and quiescent flux over comparable temporal baselines. This stability is even more pronounced in eRO-QPE2 due to its 2.4 hour average recurrence time compared to GSN-069's 9 hour, eRO-QPE1's 16 hour, and eRO-QPE3's 20 hour recurrence times, i.e., this system has undergone 4-8 times more cycles than these other systems over the 3.5 years of observations. We discuss the implications of these observations within the context of some proposed extreme mass ratio inspiral (EMRI) models.