标题： QPE 或 QPO？ -- 低质量星系核中的准周期活动 显示英文标题

标题： QPE or QPO? -- Quasiperiodic Activity in Low-Mass Galaxy Nuclei

摘要： 低质量星系中心的拟周期性爆发（QPEs）可能是由于白矮星从一个非常偏心的轨道上的中心超大质量黑洞吸积物质而产生的。 在引力辐射损失的作用下，轨道分离和偏心率会减小。 我注意到，在低于临界偏心率$e_{\rm crit} \simeq 0.97$时，近日点通过时吸积盘的粘滞时间尺度可能比轨道周期$P$长，因此周期性的爆发行为不再可能发生。 这些QPE后继系统（QPEDs）很可能会产生准周期振荡（QPOs），而不是爆发，并且在轨道周期内表现出更平滑的变化，具有$\sim1$的占空比。 我将2XMM J123103.2+110648 ($P \simeq 3.9$~小时) 和（较不确定地）RE J1034+396 ($P \simeq 1$~小时) 确认为这类系统的候选者，并发现它们推导出的偏心率$e < e_{\rm crit}$一致。 由于引力辐射损失较小，缺乏爆发以及较低的吸积亮度可能会使QPED系统更难被发现。 最终，它们必须演化到粘滞时间远长于轨道周期，要么保持稳定，要么可能有不频繁但规模较大的爆发。 后者将是低恒星质量X射线双星产生的软X射线暂现源的大质量对应物。 显示英文摘要

摘要： Quasiperiodic eruptions (QPEs) from low-mass galaxy centres may result from accretion from a white dwarf in a very eccentric orbit about the central massive black hole. Evolution under gravitational radiation losses reduces the separation and eccentricity. I note that below a critical eccentricity $e_{\rm crit} \simeq 0.97$, the accretion disc's viscous timescale at pericentre passage is probably longer than the orbital period $P$, and periodic eruptive behaviour is no longer possible. These QPE descendant systems (QPEDs) are then likely to produce quasiperiodic oscillations (QPOs) rather than eruptions, varying more smoothly over the orbital cycle, with duty cycles $\sim1$. I identify 2XMM J123103.2+110648 ($P \simeq 3.9$~hr) and (more tentatively) RE J1034+396 ($P \simeq 1$~hr) as candidate systems of this type, and find agreement with their deduced eccentricities $e < e_{\rm crit}$. The absence of eruptions and the lower accretion luminosities resulting from the smaller gravitational radiation losses may make QPED systems harder to discover. Ultimately they must evolve to have viscous times much longer than the orbital period, and either remain steady, or possibly have infrequent but large outbursts. The latter systems would be massive analogues of the soft X-ray transients produced by low stellar-mass X-ray binaries.