理论物理与天体物理研究所系列讲座之190:The global star formation laws in galaxies

题目:The global star formation laws in galaxies
 
时间:6月5日下午2:30
 
地点:物机大楼573
 
报告人:中科院紫金山天文台高煜研究员,国家杰出青年
 
摘要: The global star formation law --- the relation between gas and star
formation rate (SFR)—is studied in a large sample of 181 local galaxies
with infrared (IR) luminosities spanning almost five orders of magnitude.
The surface density of dense molecular gas (as traced by HCN) has
the tightest correlation with that of SFR (ΣSFR), and is linear. The ΣSFR
is a steeper function of total gas Σgas (molecular gas with atomic gas)
than that of molecular gas ΣH2. Because the massive dense cores in giant
molecular clouds/complexes are the sites of the active star formation. We
further show that the SFR and a variety of dense gas tracers (HCN, CS, their
high-J, high-J CO) are all linearly correlated for both the Galactic dense
cores in our Milky Way and star-forming galaxies near and far. This has
immediate implications on the modes of star formation in galaxies and
suggests that dense cores are the basic units in contributing to the star
formation and the SFR might depend linearly upon the mass of dense molecular
gas (the dense gas star formation law). These ground-based observations of
last decade and recent Herschel results highlight what ALMA can deliver on
the studies of star formation law at all redshifts and all scales.