A Complete Census of the Quasar Population in the Large Survey Era

天体物理学中的一个长期问题是了解星系在其一生中是如何形成和发展的。这样的理解对于揭示我们的宇宙是如何进化的以及洞察我们银河系的起源是必要的。了解星系形成和演化的一个重要方面是研究大质量星系中心的超大质量黑洞(BHS)。这些BHS在相对较短的阶段以类星体的形式发光，当时BHS通过吸积积累了大部分质量。在过去的半个世纪里，人们付出了相当大的努力来通过光学波长的测量来捕捉这些吸积喷发。总体而言，这些调查仅限于最明亮的光源，或深部区域内的少数；然而，由于新的和即将进行的调查，类星体观测在深度和广度上都经历了指数级的飞跃。斯隆数字天空探测III(SDSS-III/BOSS)的重子振荡光谱探测最终数据发布将包括大约160,000个红移约为2-3的类星体，其后续设备SDSS-IV/EBSS将获得红移约为1-2的超过60万个类星体的光谱。研究人员将用他们自己的高红移计划来补充这些宇宙学调查中的类星体样本，以形成光学调查中微弱类星体演化的完整图景。研究人员将把科学项目整合到位于图森的西语裔服务机构皮马社区学院的分级外展项目中。外展计划包括(1)在东校区的公开讲座，这是亚利桑那大学的计划没有达到的地区；(2)向PIMA的天文学101学生讲课，将活动星系核的概述整合到常规课程中；以及(3)通过教授类星体光谱学基础知识和包括EBOSS计划的学生对类星体光谱进行目视检查，让少数PIMA学生参与研究计划本身。更多的技术上，在稀疏数据(LSST的重要先驱)的制度下探索这种方法，该团队将利用大型天气观测望远镜(LSST)对SDSS成像数据的缩减，通过可变性选择来识别z=4附近红移的大约400个类星体。最后，该团队将使用深度CFHT成像，在z=5附近红移时到达微弱类星体(I_AB=24)。这些数据将在较大的红移范围内探测到低于断裂光度的几个量级，并将到达几乎所有可归类为类星体的宇宙演化超过5 Gyr的天体，包括恒星形成和类星体活动达到顶峰的关键时期。利用大规模的光谱测量以及用大型望远镜进行的单独观测，该团队将完成对类星体光度函数的微弱末端的普查，以红移z=5左右，并获得高z星团的新测量结果，从而为类星体寿命和反馈物理模型提供强有力的约束。这些测量也将对He II再电离时期的类星体电离背景提供强有力的约束。最后，该项目的一个关键方面是开发所需的工具，以适应类星体调查将由系统学而不是统计学主导的时代。该团队将通过建立受现有观测约束的类星体属性模型来实现这一点，但这些模型为未来的调查提供了有用的预测。这些模型将用于指导光谱工作的目标选择，从光度学数据识别类星体，并训练光度学红移估计；此外，它们将提供对类星体的内在属性的洞察，如连续体和尘埃消光。

A longstanding problem in astrophysics is to understand how galaxies form and develop throughout their lifetimes. Such understanding is necessary to uncover how our Universe evolved and to gain insight into the origin of our own Milky Way Galaxy. One important aspect of understanding galaxy formation and evolution is to study supermassive black holes (BHs) at the centers of massive galaxies. These BHs light up as quasars during the relatively brief phases when the BHs accumulate most of their mass through accretion. Over the past half-century, considerable effort has been devoted to capturing these accretion spurts through surveys at optical wavelengths. In general, these surveys have been limited to the most luminous sources, or small numbers within deep fields; however, quasar observations are undergoing an exponential leap in depth and breadth enabled by new and upcoming surveys. The Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III (SDSS-III/BOSS) final data release will include about 160,000 quasars at redshifts around 2--3, and its successor, the SDSS-IV/eBOSS, will obtain spectra of over 600,000 quasars at redshifts around 1--2. The investigators will complement the quasar samples from these cosmology surveys with their own high redshift programs to form a complete picture of the evolution of faint quasars from optical surveys. The investigators will integrate the science program into a tiered outreach program at Pima Community College, a Hispanic-Serving Institution located in Tucson. The outreach program includes (1) public lectures at the East Campus, a region not reached by The University of Arizona programs, (2) lectures to Astronomy 101 students at Pima integrating an overview of Active Galactic Nuclei into the regular curriculum, and (3) engagement of a small number of Pima students in the research program itself by teaching the basics of quasar spectroscopy and including the students in the eBOSS program to visually inspect quasar spectra.More technically, exploring this method in the regime of sparse data (an important precursor for LSST), the team will utilize Large Synoptic Survey Telescope (LSST) reductions of SDSS imaging data to identify about 400 quasars at redshifts around z = 4 through variability selection. Finally, the team will use deep CFHT imaging to reach faint quasars (i_AB = 24) at redshift around z = 5. Together, these data will probe several magnitudes below the break luminosity over a wide redshift range and will reach nearly all objects classifiable as quasars over 5 Gyr of cosmic evolution, including the crucial epoch when both star formation and quasar activity peak.Leveraging massive spectroscopic surveys as well as separate observations with large telescopes, the team will complete the census of the faint end of the quasar luminosity function to redshift around z = 5 and obtain new measurements of high-z clustering, thereby providing strong constraints for models of quasar lifetimes and feedback physics. These measurements will also provide strong constraints on the quasar ionizing background during the epoch of He II reionization. Finally, a key aspect of the project is to develop tools needed for an era when quasar surveys will be dominated by systematics rather than by statistics. The team will accomplish this by building models for quasar properties constrained by existing observations but which provide useful projections for future surveys. These models will be used to guide target selection for spectroscopic efforts, identify quasars from photometric data, and train photometric redshift estimation; furthermore, they will provide insight into intrinsic quasar properties, such as continuum and dust extinction.