Measuring the effects of dust attenuation on the luminosities and morphologies of disk galaxies

测量尘埃衰减对盘状星系的光度和形态的影响

• 批准号: 1514835
• 负责人: Eric Bell
• 金额: $ 30.72万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1514835&HistoricalAwards=false
• 关键词: Measuring; effects; dust; attenuation; luminosities

Precisely how galaxies initially form and how they change throughout their lifetimes are among the least understood problems in astrophysics. Such understanding is necessary to uncover how our Universe evolved and to gain insight into the origin of our own Milky Way Galaxy. Many projects are centered on unraveling these mysteries and depend on interpreting observations. This project focuses on how dust in galaxies affects observations. Dust profoundly affects essentially all of the observable diagnostics of galaxies, such as their brightnesses and colors, structures (disks, bulges), color gradients and stellar mass estimates. Previous work demonstrated that more luminous disk galaxies tend to suffer more dust attenuation than low-luminosity galaxies and that their central parts suffer more dust absorption than their outer parts. Yet, two critical questions remain unanswered: (1) How does global dust attenuation---and attenuation gradients---depend simultaneously on the entire set of relevant parameters (luminosity or stellar mass, star formation rate, density or scale length, and structure)? (2) How in detail are commonly-used measures of galaxy structure affected by dust attenuation as a function of galaxy parameters? This project will study these questions by assembling samples of intrinsically similar galaxies (stellar mass, star formation rate, density, structure).In addition, the principle investigator will lead a collaborative effort to widen the use and assess the impact of effective student-centered pedagogy in University of Michigan introductory undergraduate astronomy classes (e.g., inquiry-based activities, lecture tutorials, think-pair share, diagnostic assessments and learning analytics). This project also involves training of a graduate student, including mentorship and teaching skills; the development of undergraduate research skills in the context of this research project; and involvement in outreach, including in a local elementary school.More technically, because the samples of similar galaxies are viewed from random angles and edge-on galaxies are much more strongly affected by dust attenuation, studying how the optical properties vary with inclination enables a model-independent measurement of relative dust attenuation as a function of galaxy parameters. However, this crucially depends on the ability to assemble samples of truly similar galaxies, and many previous works use at least some selection criteria that are biased by dust attenuation. This results in samples where the high and low inclination members are not truly similar, and this inclination-dependent cross-sample contamination significantly affects conclusions about the dependence of dust attenuation on galaxy parameters. A critical advance of the investigators' work is that they are developing a set of selection criteria that enables the assembly of samples of similar galaxies in a manner that is unaffected by inclination bias. This advance enables the comparison of the observed properties of samples of truly similar galaxies with unprecedented accuracy. Therefore, the goals of this project are two-fold: (1) To use wide-area near-infrared surveys and this novel inclination-independent measures of galaxy structure to select samples of truly intrinsically similar galaxies in a way that is independent of inclination to a degree never before achieved. (2) To use these samples to measure the dependence of dust attenuation on all relevant galaxy parameters in a complete, unbiased, robust and detailed manner to measure for the first time the effects of dust attenuation on SDSS-based measures of galaxy structure and to measure for the first time the radial gradients in dust attenuation as a function of galaxy properties. The investigators will release their catalogues of structural metrics and other measurements to the public.

确切地说，星系是如何最初形成的以及它们在一生中的变化方式，是天体物理学中最知名的问题之一。 这种理解对于发现我们的宇宙如何发展并洞悉我们自己银河系的起源是必要的。 许多项目集中在揭示这些谜团并依赖于解释观察结果。 该项目着重于星系中的灰尘如何影响观察结果。 灰尘深刻影响了所有可观察到的星系诊断，例如它们的亮度和颜色，结构（磁盘，凸起），颜色梯度和出色的质量估计。 先前的工作表明，比低露珠性星系更具发光的磁盘星系往往遭受灰尘衰减更多，并且其中央部分比外部部位遭受的灰尘吸收更多。 然而，两个关键问题仍未得到解决：（1）全球尘埃衰减 - 以及衰减梯度如何同时依赖于整个相关参数（光度或恒星质量，星形形成率，密度或尺度长度和结构）？ （2）如何详细介绍受尘埃衰减影响的星系结构的通常量度？ This project will study these questions by assembling samples of intrinsically similar galaxies (stellar mass, star formation rate, density, structure).In addition, the principle investigator will lead a collaborative effort to widen the use and assess the impact of effective student-centered pedagogy in University of Michigan introductory undergraduate astronomy classes (e.g., inquiry-based activities, lecture tutorials, think-pair share, diagnostic assessments and learning分析）。 该项目还涉及培训研究生，包括指导和教学技能；在该研究项目的背景下发展本科研究技能；从技术上讲，参与外展活动，包括在当地的小学中。因为从随机角度和边缘星系中观察类似星系的样品受到尘埃衰减的影响更大，因此研究光学特性随倾斜度的变化如何使模型与独立的尘埃衰减相对尘埃衰减，将其视为一个函数的函数。 但是，这至关重要的是取决于组装真正相似星系的样品的能力，许多以前的作品至少使用了一些因灰尘衰减而偏见的选择标准。 这导致样品中高和低倾斜构件并不真正相似，而这种依赖倾斜度的跨样本污染显着影响了关于尘埃衰减对星系参数的依赖性的结论。 研究人员工作的一个关键进步是，他们正在开发一套选择标准，该标准可以以不受倾斜偏见影响的方式组装相似星系的样品。 这项进展可以比较具有前所未有的精度，可以比较真正相似星系的样品的样品。 因此，该项目的目标是两个方面：（1）使用广阔的近红外调查以及这种新颖的倾向与星系结构无关的测量方法，以选择真正本质上相似星系的样本，以独立于一定程度的方式，从未实现过。 （2）使用这些样品以完整，公正，稳健和详细的方式测量灰尘衰减对所有相关星系参数的依赖性，以首次测量灰尘衰减对基于SDSS的星系结构测量的影响，并在第一次测量基于SDSS的基于SDSS的测量值，以测量第一次在尘埃衰减中，尘埃梯度是Galaxy Properies的功能。 调查人员将向公众发布其结构指标和其他测量结果的目录。