Ttile: The Kennicutt-Schmidt law 3.0: a new picture for star formation

Speaker：Jingwen Wu

Abstract:

Star formation rate is a fundamental parameter in characterizing star formation process throughout all cosmic times and special scales, both in observations and for theoretical models and simulations. The Kennicutt-Schmidt law (K-S law) is an empirical scaling-relation to connect star formation rate with observable gas content, which has been so widely used in observations and simulations, yet its physical explanation is unclear and it is usually found inaccurate or even incorrect. The Gao-Solomon correlation has improved this situation by using molecular dense gas tracer to measure dense gas only, but still face many difficulties to transfer from line luminosity to gas mass, and remains to be an empirical correlation. Our recent works has revealed that the gravitationally bound gas is the key in determining star formation in the Galaxy, which can be quantitively measured using column-density probability distribution function method. The total bound gas mass determines star formation rate, and once bound, gas will be converted into stars at a consistent efficiency. This result can also naturally explain some classical puzzles in star formation. Now we can construct a bound-gas based new version of K-S law, which not only has a clear physical meaning, but also is practical to estimate star formation rates in observations and simulations.

Introduction： 

Jingwen Wu is a professor in the School of Astronomy and Space Science at UCAS, and a researcher in the ISM group at NAOC. His research focuses on star formation in the Milky Way and nearby galaxies, and high-redshift galaxy evolution. His major contributions include connecting dense gas version of Kennicutt-Schmidt law from extragalactic scales to Galactic scales; revealing that it is gravitationally bound gas instead of total gas or dense gas that determines star formation in the Galaxy. He also used NASA’s WISE mission to discover and nominate a new type of galaxies at an important evolutionary stage, the Hot, Dust obscured galaxies. He is currently leading a multi-wavelength deep survey campaign towards the Andromeda galaxy (M31), using FAST (HI), JCMT (dust), and the upcoming CSST (CI). The reported work is newly funded by the NSFC original exploration program.

Time: 14:00-15:00, 30/December, Tuesday 

Venue: Room 506 (Large seminar room), Department of Astronomy 

You can also access the colloquium via: https://www.koushare.com/space/329883/live