发表机构
University of Tsukuba; Hirosaki University; Kanazawa University Senior High School（筑波大学; 弘前大学; 金泽大学附属高中）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过耦合一维吸积盘与二维线驱动风模拟，发现辐射压不稳定性引起的光度振荡导致UFOs间歇性出现，解释了活动星系核中UFOs探测与光度变化的关系。
AI 中文摘要
我们研究了超大质量黑洞周围吸积盘中辐射压不稳定性诱导的线驱动盘风的时间变异性。这是首次将吸积盘的一维流体动力学模拟与线驱动风的二维辐射流体动力学模拟自洽耦合，并分析其随时间演化的研究。我们的结果表明，由辐射压不稳定性引起的周期性光度振荡导致质量外流率和气体覆盖因子发生相应变化，这些气体预计可被观测为超快外流（UFOs），其延迟与风基座附近的黏滞时标相当。预期观测到UFOs的视角也随时间变化。因此，我们的结果意味着，取决于视角，即使在高光度状态下也可能探测不到UFOs，而在较低光度下也可能探测到它们。这些发现与观测一致，即UFOs并非总是在高光度下被探测到，有时甚至在较低光度下也能被探测到。对于黑洞质量为$10^{7.4}M_\odot$、在约100个史瓦西半径处的质量吸积率为$1.3L_{\rm Edd}/c^2$、黏滞参数为$\alpha=0.1$、黏滞处方参数为$\mu=0.45$的情况，质量外流率相对于光度变化显示出约2--5年的延迟，因此覆盖因子从高光度阶段到下降阶段最终达到约$30\\%$的最大值。我们的结果表明，在光度变化的活动星系核中间歇性探测到UFOs可以用辐射压不稳定性驱动的线驱动盘风的变异性来解释。
英文摘要
We investigated the temporal variability of line-driven disk winds induced by radiation pressure instability in accretion disks surrounding supermassive black holes. This is the first study to self-consistently couple one-dimensional hydrodynamic simulations of accretion disks with two-dimensional radiation hydrodynamic simulations of line-driven winds and to analyze their time-dependent evolution. Our results show that periodic luminosity oscillations caused by radiation pressure instability lead to corresponding changes in both the mass outflow rate and the covering factor of gas expected to be observed as ultra-fast outflows (UFOs), with a delay comparable to the viscous timescale around the wind base. The viewing angles from which UFOs are expected to be observed also change with time. Our results therefore imply that, depending on the viewing angle, UFOs may not be detected even during high-luminosity states, whereas they may be detected even at lower luminosities. These findings are consistent with observations showing that UFOs are not always detected at high luminosities and can sometimes be detected even at lower luminosities. For a black hole mass of $10^{7.4}M_\odot$, a mass accretion rate of $1.3L_{\rm Edd}/c^2$ at a radius of about 100 Schwarzschild radii, a viscosity parameter of $α=0.1$, and a viscosity prescription parameter of $μ=0.45$, the mass outflow rate shows a delay of approximately 2--5 yr relative to the luminosity variation, and the covering factor consequently reaches a maximum of $\sim 30\%$ from the high-luminosity phase through the declining phase. Our results suggest that the intermittent detection of UFOs in luminosity-variable AGNs can be explained by radiation pressure instability driven variability of the line-driven disk winds.
Comments11 pages, 7 figures, 2 tables, accepted for publication in PASJ
