我们展示了潮汐瓦解事件（TDE）候选体和准周期性爆发（QPE）源GSN 069的Hubble Space Telescope (HST)和XMM-Newton数据分析。利用HST分辨率的紫外（UV）和光学图像，我们表明GSN 069的辐射由叠加在弥散恒星成分上的点源组成。后者在内部0.5"×0.5"区域的UV辐射中占≤5%，而前者的光度无法归因于恒星。分析2014/2018年的HST UV光谱，我们表明在主导阶上，内禀光谱形状为νL_ν∝ν^(4/3)，且在历元之间存在约10%的远UV流量变化。同时期的X射线和UV光谱可以在薄盘框架内进行自洽建模。在观测历元，该盘的外半径（R_out）为O(10^3 R_g)，在四年内表现出冷却和膨胀。通过数值光线追踪引入相对论效应，我们将盘倾角（i）限制在30°≲i≲65°，并确定了能描述观测的自旋-倾角参数空间的狭窄区域。这些发现证实GSN 069拥有一个在TDE后形成的致密、粘性膨胀吸积盘。对QPE模型的启示是：（i）没有已发表的盘不稳定性模型能解释该盘在2014年的稳定性（无QPE）及其在2018年的不稳定性（存在QPE）；（ii）尽管2018年的盘大小允许轨道器/盘相互作用产生QPE，但在2014年盘已经足够延伸，却不存在QPE。这些发现对现有QPE模型构成了挑战。
英文摘要：
We present an analysis of Hubble Space Telescope (HST) and XMM-Newton data of the tidal disruption event (TDE) candidate and quasi-periodic eruption (QPE) source GSN 069. Using ultraviolet (UV) and optical images at HST resolution, we show that GSN 069's emission consists of a point source superimposed on a diffuse stellar component. The latter accounts for $\leq 5\%$ of the UV emission in the inner 0.5"$\times$0.5" region, while the luminosity of the former cannot be attributed to stars. Analyzing the 2014/2018 \hst UV spectra, we show that to leading order the intrinsic spectral shape is $ν\,L_ν\proptoν^{4/3}$, with $\sim10\%$ far UV flux variability between epochs. The contemporaneous X-ray and UV spectra can be modeled self-consistently in a thin disk framework. At observed epochs, the disk had an outer radius ($R_{\rm out}$) of $\mathcal{O}(10^3R_{\rm g})$, showing both cooling and expansion over four years. Incorporating relativistic effects via numerical ray tracing, we constrain the disk inclination angle ($i$) to be $30^\circ\,\lesssim\,i\,\lesssim\,65^\circ$ and identify a narrow region of spin-inclination parameter space that describes the observations. These findings confirm that GSN 069 hosts a compact, viscously expanding accretion disk likely formed after a TDE. Implications for QPE models are: (i) No published disk instability model can explain the disk's stability in 2014 (no QPEs) and its instability in 2018 (QPEs present); (ii) While the disk size in 2018 allows for orbiter/disk interactions to produce QPEs, in 2014 the disk was already sufficiently extended, yet no QPEs were present. These findings pose challenges to existing QPE models.
No evidence for a supermassive black hole binary in GSN 069
Tsung-Dao Lee Institute, Shanghai Jiao-Tong University（上海交大李政道研究所）；School of Physics & Astronomy, Shanghai Jiao-Tong University（上海交通大学物理与天文学院）；Institute for Astronomy, School of Physics, Zhejiang University（浙江大学物理学院天体物理研究所）；Center for Cosmology and Computational Astrophysics, Institute for Advanced Study in Physics, Zhejiang University（浙江大学物理学高等研究院宇宙学与计算天体物理中心）；Department of Astronomy, University of Science and Technology of China（中国科学技术大学天文系）
Massachusetts Institute of Technology（麻省理工学院）；Institute for Advanced Study（高等研究院）；Princeton University（普林斯顿大学）；Harvard University（哈佛大学）；New York University（纽约大学）
QPEs from Warped Disk Collisions with EMRIs: Brightness-Recurrence Diagram and Gravitational-Wave Follow-up
Wuhan University（武汉大学）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家航空航天技术研究委员会-国家航空技术研究所）；University of Science and Technology of China（中国科学技术大学）；Tsung-Dao Lee Institute, Shanghai Jiao-Tong University（上海交大李政道研究所）；Shanghai Jiao-Tong University（上海交通大学）
