标题： 耀变体 AO 0235+164 长时间多波段光学光变曲线的变化性研究 显示英文标题

标题： Study of variability in long-term multiwavelength optical lightcurves of blazar AO 0235+164

摘要： 我们展示了对耀变体AO 0235+164在多波段（$U\!BV\!RI$）光学数据的长期和日内变异性研究，这些数据由各种望远镜收集了$\sim$44年（1975–2019）。 发现该耀变体在所有波段多年来表现出显著的变化，在其低态和活跃态之间大约有六个星等的变化。 不同波段的变化高度相关且没有时间延迟。 我们没有观察到颜色随时间变化有显著趋势，但观测到了$B-I$颜色指数与$R$亮度之间的“越亮越蓝”趋势。 光学$BV\!R$波段的光谱能量分布总是呈现凸形。 在1999年至2019年期间，由CASLEO和CAHA望远镜在$R$和$V$波段的22个夜晚的准同时观测中，频繁发现了显著的日变变异性。 我们还通过分析AO 0235+164光谱中的宽Mg II发射线，估算了$7.9\times10^7 M_{\odot}$的中心超大质量黑洞的质量。 我们简要探讨了导致观测到的变化的可能物理场景。 显示英文摘要

摘要： We present a long-term and intraday variability study on optical multiwaveband ($U\!BV\!RI$) data from the blazar AO 0235+164 collected by various telescopes for $\sim$44 years (1975--2019). The blazar was found to be significantly variable over the years in all wavebands with a variation of about six magnitudes between its low and active states. The variations in the different wavebands are highly correlated without any time lag. We did not observe any significant trend in color variation with time, but we observed a bluer-when-brighter trend between the $B-I$ color index and the $R$-magnitude. Optical $BV\!R$-band spectral energy distributions always show a convex shape. Significant intraday variability was frequently seen in the quasi-simultaneous observations of AO\,0235+164 made on 22 nights in $R$ and $V$-bands by the CASLEO and CAHA telescopes during 1999--2019. We also estimated the central supermassive black-hole mass of $7.9\times10^7 M_{\odot}$ by analyzing the broad Mg II emission line in AO 0235+164's spectrum. We briefly explore the probable physical scenarios responsible for the observed variability.