The role of galaxy-galaxy interactions in Galaxy evolution

邻近的宇宙中有星系相互作用的惊人例子。这一过程在引力作用下破坏了一个或两个星系，并可能导致合并。与此同时，这些近距离接触既可以触发新一代恒星的形成，也可以（后来）熄灭这些星系中恒星的形成。近年来，对相互作用星系的研究大大提高了我们对这些过程的理解，尽管还有很多东西需要学习。一个关键的挑战是将这些相互作用星系的观测与更典型的（孤立的）星系联系起来，这些星系可能经历了相对较近的相互作用，深刻地改变了它们的进化史。拟议的研究计划将以我们最近在这一领域的贡献为基础，并将采用我们为此目的收集的一套非凡的数据和环境分类。我们已经使用这个数据库来识别大量紧密成对和紧密群体的星系，它们提供了理想但独特的环境，可以在其中检测正在进行的、最近的和即将发生的相互作用。我们将通过测量成对星系和紧致星系群的广泛属性，通过将这些属性与定义良好的控制样本中的星系进行比较，通过将近对与宽对联系起来，以及将紧致星系群与周围的星系联系起来，来实现我们的科学目标。有了诸如尺寸-光度关系、质量-金属丰度关系、颜色-颜色图和恒星形成历史等指标，我们将大大提高我们对星系演化中相互作用的理解。我们现有的星系对和致密群样本在星系数量、测量指数的质量和广度、复杂控制样本的使用以及直接将相互作用的星系与那些目前没有相互作用的星系联系起来的能力方面都是无与伦比的。此外，我们有足够的专业知识在未来的许多年里利用这些资源，并继续让博士后、研究生和本科生参与这项令人兴奋的合作努力。

The nearby universe contains striking examples of galaxies which are interacting with one another. This process gravitationally disrupts one or both galaxies, and may result in a merger. At the same time, these close encounters can both trigger the formation of new generations of stars and (later) quench star formation in these galaxies. The study of interacting galaxies has greatly improved our understanding of these processes in recent years, though much remains to be learned. A crucial challenge is to relate the observations of these interacting galaxies to more typical (isolated) galaxies, which may nevertheless have undergone relatively recent interactions that have profoundly altered their evolutionary histories. The proposed research program will build on our recent contributions in this field, and will employ an extraordinary set of data and environmental classifications that we have assembled for this purpose. We have used this database to identify large numbers of galaxies in close pairs and compact groups, which provide ideal but distinct environments within which to detect ongoing, recent and imminent interactions. We will address our science goals by measuring a wide range of properties for galaxies in pairs and compact groups, by comparing these properties to galaxies in well defined control samples, by relating close pairs to wide pairs, and by relating compact group galaxies to those in their surroundings. With metrics such as the size-luminosity relation, the mass-metallicity relation, the colour-colour diagram, and star formation histories, we are poised to greatly improve our understanding of the role of interactions in galaxy evolution. Our existing samples of galaxy pairs and compact groups are unparalleled in terms of the number of galaxies, the quality and breadth of indices measured, the use of sophisticated control samples, and the ability to directly relate interacting galaxies to those which are not currently undergoing interactions. Moreover, we have the expertise in place to exploit these resources for many years to come, and to continue to involve postdocs, graduate students, and undergraduate students in this exciting collaborative endeavour.