Collaborative Research: Gaseous Halos of Nearby Galaxies as Clues to Galaxy Evolution

兰德博士和沃特博斯博士将从附近几十个边缘螺旋星系的中间平面寻找热电离气体和中性气体。这种弥漫性气体的旋转速度比盘面赤道面上密度更大的冷气体慢；这种滞后仍未被理解，并可能为气体的起源提供线索。研究小组将使用ARC 3.5米望远镜的新型多缝模式，在7个恒星形成旺盛的边缘星系和2个恒星诞生率较低的边缘星系中测量这种气体电离氢的发射线。他们还将完成和分析用国家射电天文台的超大阵列在B和C阵列观测到的四个星系的21厘米中性氢线的地图，并将使用荷兰的韦斯特伯克阵列对另外八个星系进行深入观测。这些“数据立方体”中的速度信息将用于区分偏离平面的气体与翘曲或其他结构，并确定其旋转。目的是利用速度信息来确定离面气体是刚刚落入，还是已经从形成恒星的圆盘中喷射出来。这项研究将成为两篇博士论文的基础。新墨西哥大学和新墨西哥州立大学都是为西班牙裔服务的机构，新墨西哥州立大学的天文学家在公共宣传方面尤为活跃。

Dr Rand and Dr. Walterbos will search for warm ionized and neutral gas away from the mid-plane of a couple of dozen nearby edge-on spiral galaxies. This diffuse gas rotates more slowly than the denser cool gas in the equatorial plane of the disk; this lag is still not understood, and may hold a clue to the origin of the gas. The team will use the new multi-slit mode of the ARC 3.5-m telescope to measure emission lines of ionized hydrogen from this gas in 7 edge-on galaxies that have vigorous star formation and two with lower rates of starbirth. They will also complete and analyze maps in the 21cm line of neutral hydrogen for four galaxies observed in B and C arrays with the National Radio Astronomy Observatory's Very Large Array, and will use the Westerbork array in the Netherlands to make deep observations for a further eight galaxies. The velocity information in these 'data cubes' will be used to distinguish off-plane gas from a warp or other structure, and to determine its rotation. The aim is to use the velocity information to determine whether the off-plane gas is newly falling in, or has been ejected from the star-forming disk. This research would form the basis for two PhD theses. Both the University of New Mexico and New Mexico State University are Hispanic-serving institutions, and the astronomers at New Mexico State University are particularly active in public outreach.