A Systematic Search for Detached Tidal Dwarf Galaxies

我们的银河系是宇宙中数十亿个星系之一。 它是一个由恒星组成的扁平圆盘。 银河系正处于与一个类似的盘状星系仙女座星系碰撞的过程中。 星系之间的这种引力相互作用改变了星系的结构。 碰撞过程中的潮汐力产生了长长的恒星流光，延伸到数十万光年的太空中。 这些被称为潮汐尾。 在这些尾巴中的恒星密度类似于在银河系附近观察到的小矮星系。 一些潮汐矮星系可能会从它们的母星系中分离出来，成为独立的矮星系。 另外，潮汐矮星可能会随着时间的推移而分散，它们的恒星遍布星系际空间。 第三种可能性是这些潮汐矮星可能会落回它们的母星系。 从原来的星系中分离出来的潮汐矮星的数量还不清楚。 研究人员试图了解这些星系在相互作用过程中产生的残余物，并测试这些矮星系的观测是否可以用来了解星系形成的历史。 研究者将聘请本科生作为研究助理。 这些学生将接受数据分析，解决问题和科学技术的培训。 将鼓励它们在地方和区域会议上介绍其成果。 这一经验将使学生更好地为科学家、教师或数据分析师的职业生涯做好准备。研究人员将比较邻近相互作用星系附近的潮汐矮星系和孤立盘星系的对照样本。 紫外线、可见光和红外线图像将在这些星系附近寻找可能的潮汐矮星。 这些物体的性质将与其他矮星系的性质进行比较。 研究结果将与潮汐矮星形成和演化的计算机模拟结果进行比较。 潮汐矮星系的最终名单将向公众公布。 这个项目的结果将检验星系形成的理论。 宇宙年轻时，星系间的相互作用更为常见。 潮汐矮星系不容易在更遥远的星系中进行研究。 然而，它们可以很容易地在附近的相互作用星系中进行研究。 研究人员将使用来自红外（IR），紫外（UV）和光学望远镜的档案数据，包括斯隆数字化巡天。 相互作用的星系样本包括46对附近的星系潮汐尾巴。 控制样本是一组39个正常的旋涡星系。 目标星系周围的图像将搜索可能的潮汐矮星系。 紫外/光学/红外数据将与老化恒星群模型进行比较，以确定这些区域恒星的平均年龄和恒星的总质量。 样本中的星系的中位距离仅为44百万秒差距;因此，调查将对星星形成率为每年0.001太阳质量和恒星质量为100，000太阳质量的区域敏感。 相互作用星系周围可能的潮汐矮星的数量将与正常螺旋附近的潮汐矮星进行比较，以确定是否有多余的相互作用星系。

Our home galaxy, the Milky Way, is one of billions of galaxies in the Universe. It is a flattened disk of stars. The Milky Way is on a collision course with a similar disk galaxy, the Andromeda galaxy. Such gravitational interactions between galaxies change the structure of the galaxies. Tidal forces during the collision produce long streamers of stars that extend hundreds of thousands of light years into space. These are called tidal tails. Concentrations of stars in these tails resemble the small dwarf galaxies observed near the Milky Way. Some tidal dwarf galaxies may separate from their parent galaxies to become independent dwarf galaxies. Alternatively, tidal dwarfs may disperse with time with their stars being spread throughout intergalactic space. A third possibility is that these tidal dwarfs may fall back into their parent galaxy. The number of tidal dwarfs that detach from their original galaxies is not yet known. The investigator seeks to understand the remnants of these galaxies created during interactions and test whether observations of these dwarf galaxies be used to understand the history of galaxy formation. The investigator will employ undergraduate students as research assistants. These students will be trained in data analysis, problem solving, and scientific techniques. They will be encouraged to present their results at local and regional conferences. This experience will better prepare the students for careers as scientists, teachers, or data analysts.The investigator will compare the tidal dwarf galaxies near nearby interacting galaxies and a control sample of isolated disk galaxies. Ultraviolet, visible light, and infrared images will be searched for possible tidal dwarfs near these galaxies. The properties of these objects will be compared to those of other dwarf galaxies. The results will be compared to computer simulations of tidal dwarf formation and evolution. The final list of tidal dwarf galaxies will be made available to the public. The results of this project will test theories of galaxy formation. Galaxy interactions were more common when the Universe was younger. Tidal dwarf galaxies cannot be easily studied in more distant galaxies. However, they can be easily studied in nearby interacting galaxies. The investigator will use archival data from the infrared (IR), ultraviolet (UV) and optical telescopes, including the Sloan Digitized Sky Survey. The interacting galaxy sample includes 46 nearby pairs of galaxies with tidal tails. The control sample is a set of 39 normal spiral galaxies. The images around the targeted galaxies will be searched for possible tidal dwarf galaxies. The UV/optical/IR data will be compared to models of aging stellar populations to determine the average age of the stars in these regions and the total mass of the stars. The galaxies in the sample have a median distance of only 44 megaparsecs; thus, the survey will be sensitive to regions with star formation rates of 0.001 solar masses per year and stellar masses of 100,000 solar masses. The numbers of possible tidal dwarfs around the interacting galaxies will be compared with those near the normal spirals to determine whether there is an excess near interacting galaxies.