论文标题
阿尔玛（Alma
ALMA Resolves Giant Molecular Clouds in a Tidal Dwarf Galaxy
论文作者
论文摘要
潮汐矮星系（TDGS）是在星系相互作用期间形成的气体和恒星的重力凝结。在这里，我们介绍了J1023+1952的多种配置ALMA观察，在相互作用的系统ARP 94中的TDG，我们在0.64“ 〜45pc分辨率下，我们解决了巨大的分子云（GMC），从而降低了巨大的分子云（GMC）。〜45pc分辨率〜45pc分辨率。我们发现了较高的距离分子的范围，这可能是分子的较高范围（〜80％），〜80-90％，〜80-90％，〜80-90％，〜80-90％，〜80-90-90-90-90-90-90-90-90-90-90％0％，〜80-90％，〜80-90-90-90-9。我们检测到111个GMC，其质谱与银河系和附近的其他星系相似（斜率为-1.76 +/- 0.13）分散较高，使得尺寸宽度和病毒关系显得超线性，偏离了典型的分子气体比率。在〜50pc到〜200pc之间在此TDG中，ISM与大尺度上的其他类型的星系完全不同，但是GMC的特性似乎相当相似，指出小尺度上恒星形成过程的近乎通用性。
Tidal dwarf galaxies (TDGs) are gravitationally bound condensations of gas and stars formed during galaxy interactions. Here we present multi-configuration ALMA observations of J1023+1952, a TDG in the interacting system Arp 94, where we resolve CO(2-1) emission down to giant molecular clouds (GMCs) at 0.64" ~ 45pc resolution. We find a remarkably high fraction of extended molecular emission (~80-90%), which is filtered out by the interferometer and likely traces diffuse gas. We detect 111 GMCs that give a similar mass spectrum as those in the Milky Way and other nearby galaxies (a truncated power law with slope of -1.76+/-0.13). We also study Larson's laws over the available dynamic range of GMC properties (~2 dex in mass and ~1 dex in size): GMCs follow the size-mass relation of the Milky Way, but their velocity dispersion is higher such that the size-linewidth and virial relations appear super-linear, deviating from the canonical values. The global molecular-to-atomic gas ratio is very high (~1) while the CO(2-1)/CO(1-0) ratio is quite low (~0.5), and both quantities vary from north to south. Star formation is predominantly taking place in the south of the TDG, where we observe projected offsets between GMCs and young stellar clusters ranging from ~50pc to ~200pc; the largest offsets correspond to the oldest knots, as seen in other galaxies. In the quiescent north, we find more molecular clouds and a higher molecular-to-atomic gas ratio (~1.5); atomic and diffuse molecular gas also have a higher velocity dispersion there. Overall, the organisation of the molecular ISM in this TDG is quite different from other types of galaxies on large scales, but the properties of GMCs seem fairly similar, pointing to near universality of the star-formation process on small scales.
