Quasars Probing Quasars

类星体 探测类星体

• 批准号: 1412981
• 负责人: Jason Prochaska
• 金额: $ 39.14万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-15 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1412981&HistoricalAwards=false
• 关键词: Quasars; Probing

In the fifty years since the discovery of quasars, a picture of these enigmatic objects has emerged wherein quasars are supermassive black holes residing at the centers of large galaxies. The black hole may have a mass of millions to billions times that of the sun. As this picture implies, the quasar phenomenon is one and the same as that of the objects referred to as "active galactic nuclei." All are characterized by enormous luminosity such that the quasar frequently outshines the light from all of the billions of stars in its host galaxy. Their extreme luminosity makes it possible to observe quasars located at billions of light-years from earth. Due to the finite speed of light, this means that astronomers can literally observe quasars at an earlier epoch in the universe, the age of the formation of galaxies. This project will specifically study pairs of quasars. Quasar pairs are relatively rare and are not physically associated with one another. Instead, they are a superposition of two quasars at different distances that appear close together on the sky. As the light from the more distant quasar passes by the nearer one, any gas in the halo of the galaxy hosting the latter quasar, the so-called "circumgalactic medium," imprints a signature on the spectrum of the more distant quasar, allowing the study of the characteristics of that gas and giving clues as to the mechanism of the formation of the host galaxy. This team of researchers has assembled a sample of such pairs and will use them to study the circumgalactic gas as well as the gas between galaxies. The project will also support internship programs at a minority-serving college and public outreach.This project is an extension of the well-established Quasars Probing Quasars project into several new scientific directions and support astronomical outreach into the Hispanic community of Salinas Valley. Specific scientific emphasis will be concentrated on the circumgalactic medium of massive galaxies, AGN physics, and the intergalactic medium at redshift of about 2. The project will utilize data from essentially every large-aperture, optical/near-IR telescope and will leverage state-of-the-art cosmological simulations to interpret results and test theories of galaxy formation, quasar feedback, cosmic re-ionization, and supermassive black hole evolution. The core of the project will be the use of pairs of quasars to probe the intergalactic and circumgalactic media at high redshift as well as to provide evidence for the resolution of fundamental questions in quasar physics. Typical quasar pairs are not physically associated with one another but the light from the background quasar is imprinted by material associated from the nearer, lower redshift member of the pair. This allows determination of the size of structure in any absorbing gas along with its density, mass, etc. Three distinct but coupled programs will be supported: (1) to test theories of galaxy formation by elucidating the properties of the circumgalactic medium around galaxies hosting quasars and sub-millimeter galaxies; (2) to estimate timescales for the active galaxy phenomenon using the transverse proximity effect; and (3) make the first measurements of the small scale structure of the intergalactic medium at redshifts around 2. This is an ambitious program for which the PI and his collaborators have the necessary physical resources (telescope time, etc.) and intellectual prowess.

自从发现类星体以来的五十年来，出现了这些神秘物体的图片，其中类星体是居住在大星系中心的超级质量黑洞。黑洞可能有数百万到十亿次的太阳。正如这张图所暗示的那样，类星体现象与称为“活跃银河核”的对象相同。所有这些都以巨大的光度为特征，使得准经常超过其宿主星系中所有数十亿颗恒星的光。他们的极端亮度使观察地球数十亿光年的类星体成为可能。 由于光的有限速度，这意味着天文学家可以从字面上观察到宇宙中早期时期的类星体，即星系形成的时代。 该项目将专门研究类星体。 类星体对相对较少，并且在物理上彼此之间不相关。取而代之的是，它们是两个类星体的叠加，在天空上靠近的不同距离。 随着较远的类星体的光通过近较距离的光线，在星系的光环中，托有后者的Quasar的任何气体，即所谓的“圆形培养基”，在较远的类星体的范围内贴上了签名，从而使该气体的特征和线索允许将主机的机构赋予主机的机构。 这个研究人员团队组装了这样的对样本，并将使用它们来研究海洋气体以及星系之间的气体。 该项目还将支持少数派服务学院和公共宣传的实习计划。该项目是将良好的类星体探测类星体项目伸展到几个新的科学方向的延伸，并支持天文学宣传到萨利纳斯山谷的西班牙裔社区。 具体的科学重点将集中在大约2的大规模星系，AGN物理学和层次介质的圆形介质上超大黑洞的演变。 该项目的核心将是使用成对的类星体在高红移处探测绘制的媒介和近代培养基，并为解决类星体物理学基本问题的解决提供了证据。 典型的类星体对没有物理上的相互关联，但是背景的光子是由靠近的，较低的红移构件相关的材料印刷的。 这允许在任何吸收气体的密度，质量等中确定结构的大小。将支持三个不同但耦合的程序：（1）通过阐明围绕星系围绕托管的星系和次级星系的星系培养基的特性来测试星系形成的理论； （2）使用横向接近效应来估算活动星系现象的时间尺度； （3）对红移大约2的层间介质的小规模结构进行了首次测量。这是一个雄心勃勃的计划，PI和他的合作者为此具有必要的物理资源（望远镜时间等）和知识上的实力。