A Systematic Search for Detached Tidal Dwarf Galaxies

我们的银河系是宇宙中数十亿个星系中的一个。它是一个扁平的星盘。银河系正在与一个类似的盘状星系--仙女座星系相撞。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量产生了延伸数十万光年进入太空的长长的恒星流光。这些被称为潮汐尾巴。这些尾巴中恒星的密度类似于银河系附近观察到的小矮星系。一些潮汐矮星系可能会从其母星系中分离出来，成为独立的矮星系。或者，潮汐矮星可能会随着时间的推移而消散，它们的恒星散布在星际空间中。第三种可能性是，这些潮汐矮星可能会落回它们的母星系。目前尚不清楚脱离其原始星系的潮汐矮星的数量。研究人员试图了解在相互作用过程中产生的这些星系的残留物，并测试对这些矮小星系的观测是否可以用来了解星系形成的历史。调查员将雇用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方面的培训。将鼓励他们在地方和区域会议上介绍他们的成果。这一经历将更好地为学生将来成为科学家、教师或数据分析员做好准备。研究人员将比较附近相互作用的星系附近的潮汐矮星系和孤立的盘状星系的对照样本。紫外线、可见光和红外图像将在这些星系附近搜索可能的潮汐矮星。这些天体的性质将与其他矮小星系的性质进行比较。结果将与潮汐矮星形成和演化的计算机模拟进行比较。潮汐矮星系的最终名单将向公众公布。该项目的结果将检验星系形成的理论。星系间的相互作用在宇宙较年轻的时候更为常见。潮汐矮星系很难在更遥远的星系中被研究。然而，它们可以很容易地在附近相互作用的星系中进行研究。研究人员将使用红外线(IR)、紫外线(UV)和光学望远镜的档案数据，包括斯隆数字化天空调查。相互作用的星系样本包括46对附近的带有潮汐尾巴的星系。对照样本是一组39个正常的螺旋星系。目标星系周围的图像将被搜索，以寻找可能的潮汐矮星系。UV/光学/IR数据将与老化恒星群的模型进行比较，以确定这些地区恒星的平均年龄和恒星的总质量。样本中星系的中位数距离只有44兆秒；因此，调查将对恒星形成率为每年0.001个太阳质量和恒星质量为100,000个太阳质量的区域很敏感。相互作用星系周围可能的潮汐矮星数量将与正常螺旋线附近的潮汐矮星数量进行比较，以确定相互作用星系附近是否存在过剩。

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.