Mapping AGN Accretion Through Echo Mapping and Radiation MHD Simulations

从恒星和行星的形成到最极端的爆炸（如伽马射线暴），了解流向物体的物质是天体物理学中的一个普遍挑战。这个研究项目的pi利用对流入超大质量黑洞（吸积盘）的物质的观测来完善吸积模型。具体来说，我们观察到吸积盘在不同波长的光量随时间的变化。在很长的时间尺度上，他们可以有效地观察物质通过这种变化在吸积盘中向内移动，这反过来告诉我们关于吸积盘的基本信息，比如它有多厚，密度有多高。然后，他们将建立新的吸积盘模型，这将帮助我们准确地了解信号是如何通过吸积盘传播的。随着即将到来的维拉鲁宾望远镜遗产时空调查（LSST）准备观测黑洞周围数千个吸积盘，现在是时候让这些模型和我们的测量工具准备好了。普林斯顿大学的pi也将在培养下一代科学家利用LSST方面处于有利地位。除了与pi合作的学生和博士后之外，他们还为曾经被监禁的学生建立了一个暑期研究项目，与该项目相关的短期暑期项目将为这些学生的STEM职业和未来参与LSST做好准备。活动星系核（AGN）中超大质量黑洞的吸积是宇宙中能量最高的现象之一，而AGN的反馈可能在星系演化中起着核心作用。然而，尽管经过多年的研究，我们对吸积的机制仍然有一些基本的开放性问题。虽然我们不能直接在空间上分辨吸积盘，但回波映射——用波长跟踪可变性信号——可以告诉我们吸积盘的温度分布、大小比例，甚至宽高比。最后一个特性可以通过追踪在吸积盘中远距离产生的变异性信号来探测，这些变异性信号在粘性时间内随着气流向内移动，即所谓的“负”滞后，从红色波长移动到蓝色波长。该奖项的pi已经在一个经过充分研究的AGN中发现了这样的负滞后，该项目的重点是通过以下方式发现更多这样的负滞后：(a)档案搜索；(b)三维辐射磁流体动力学模拟，这将使我们深入了解响应函数，或信号向内移动时的延迟分布；(c)根据(b)创建模拟光曲线，以优化延迟恢复和下一代调查的节奏，如维拉鲁宾天文台的空间和时间遗产调查。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding material flowing onto objects is a universal challenge in astrophysics, from the formation of stars and planets to the most extreme explosions like Gamma Ray Bursts. The PIs of this research program use observations of the material flowing onto supermassive black holes (accretion disks) to refine models of accretion. Specifically, we observe changes in the amount of light from accretion disks over time at different wavelengths. Over long timescales, they can effectively watch material moving inward in the accretion disk through this variability, which in turn tells us basic things about the disk, like how thick it is, and how dense. They will then build new models of accretion disks that will help us understand exactly how the signals propagate through the accretion disk. With the upcoming Vera Rubin Telescope Legacy Survey of Space and Time (LSST) poised to observe thousands of accretion disks around black holes, now is the time to get these models and our measurement tools ready. The PIs at Princeton will also be in a strong position to train the next generation of scientists to utilize LSST. In addition to the students and postdocs that the PIs collaborate with, they have built a summer research program for formerly incarcerated students, and short summer projects associated with this project will position these students for STEM careers and future involvement in LSST. Accretion onto supermassive black holes in active galactic nuclei (AGN) is one of the most energetic phenomena in the Universe, and AGN feedback likely plays a central role in galaxy evolution. Yet, despite years of study, we still have basic open questions about the mechanisms of accretion. While we cannot directly spatially resolve accretion disks, echo mapping -- tracing variability signals with wavelength -- can tell us about the temperature profile, size scale, and even aspect ratio of the disk. This last property can be probed by tracing variability signals that originate at large distance in the accretion disk and then move inwards with the flow on a viscous time, the so-called "negative" lags that move from red to blue wavelengths. The PIs of this award have detected such a negative lag in one well-studied AGN, and this project is focused on finding more such negative lags through: (a) archival searches; (b) 3D radiation magnetohydrodynamic simulations that will give us insight into the response function, or the delay distribution of the signal as it moves inward; (c) the creation of mock light curves, informed by (b), to optimize lag recovery and the cadence of next-generation surveys like the Vera Rubin Observatory Legacy Survey of Space and Time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.