Modeling light echoes from hot dust and the broad line region in Active Galactic Nuclei

我们现在知道，宇宙中的大多数星系的中心都有一个超大质量的黑洞。当星际气体落向黑洞时，释放出大量的能量，在星系的中心形成了一个极其明亮的光源。这些源被称为活动星系核，可以远远超过整个银河系的恒星数量。由于星系间距离遥远，即使用目前的望远镜获得最好的图像，也很难分辨出活跃的星系核。然而，通过测量“光回声”，天文学家可以探测黑洞周围的环境。在这个项目中，PI将开发一个计算机程序来模拟这些光回声。通过将计算机生成的回声图与几次观测获得的数据进行比较，PI将能够绘制大量活动星系核中的气体和尘埃结构图。RIT校园将为当地高中生举办一系列天文和物理日活动，其中将包括专门为解决女学生的兴趣和关切而设计的讲座和活动。在活动星系核的光谱中观察到的宽广的发射线提供了各种物理性质的关键诊断，包括黑洞的质量。内部区域(“中央引擎”)被一个尘埃分子气体环所包围。这种结构遮蔽了我们的观察，严重阻碍了对黑洞成长阶段的研究。由于活动星系核距离遥远，很难用目前的望远镜直接成像来研究它们。但是，也可以使用另一种方法，称为混响映射。宽阔的发射线和嵌入环中的尘埃发出的红外辐射会对中央发动机光度的变化做出反应，但会因光行进时间而延迟。这就产生了包含发射气体和尘埃的空间分布、速度场和其他性质的信息的“光回声”。在这个项目中，PI将开发一个计算机代码，以产生宽广发射线的光回波和环状尘埃的红外发射的详细模型。PI将使用该代码对当前和近期几次观测混响地图调查的数据进行建模。通过对这些数据集进行建模，PI旨在绘制活动星系核大样本中的气体和尘埃结构图。这将有助于描述超大质量黑洞种群在宇宙时间内的演化。项目完成后，计算机代码和相关产品，如计算的回声图，将提供给科学界。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

We now know that most galaxies in the universe host a supermassive black hole at their centers. As interstellar gas falls in towards the black hole, a huge amount of energy is released, creating an extremely bright light source at the center of the galaxy. These sources, called Active Galactic Nuclei, can far outshine the galaxy’s entire population of stars. Because inter-galactic distances are vast, Active Galactic Nuclei are difficult to resolve even using the best images obtained with current telescopes. However, by measuring “light echoes” astronomers can probe the environment around the black hole. In this project, the PI will develop a computer program to model these light echoes. By comparing computer generated “echo maps” with data obtained from several observational surveys, the PI will be able to map the gas and dust structures in large numbers of Active Galactic Nuclei. A series of Astronomy and Physics Days for local high school students will be hosted at the RIT campus, which will include talks and activities specifically designed to address the interests and concerns of female students. The broad emission lines observed in the spectra of Active Galactic Nuclei provide key diagnostics of various physical properties, including the mass of the black hole. The inner region (the “central engine”) is surrounded by a torus of dusty molecular gas. This structure obscures our observations and severely hinders studies of the black hole growth phase. Due to their distances, Active Galactic Nuclei are difficult to study by direct imaging with current telescopes. However, an alternative method, known as reverberation mapping, can be used. The broad emission lines and the infrared emission from dust embedded in the torus respond to variations in the central engine’s luminosity with a delay due to light travel times. This produces a “light echo” that contains information on the spatial distribution, velocity field and other properties of the emitting gas and dust. In this project, the PI will develop a computer code to produce detailed models of the light echoes of both the broad emission lines and the infrared emission from the torus dust. The PI will use the code to model data from several current and near future observational reverberation mapping surveys. By modeling these data sets, the PI aims to map the gas and dust structures in large samples of Active Galactic Nuclei. This will help characterize the evolution of the supermassive black hole population over cosmic time. Upon completion of the project, the computer code and related products, such as the computed echo maps, will be made available to the scientific community.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.