Shanghai Astronomical Observatory Astrophysics Colloquium

Title：Weighing Galaxies with Stars: A Dynamical View from MaNGA-DYNPOP

Speaker：Prof.Ran Li (Beijing Normal University)

Time：3:00 pm Apr. 16th (Thursday)

Tencent Meeting：46822606747 password: 6360

Location: Lecture Hall, 3rd floor

Abstract：How do stars move within galaxies, and how can these motions reveal the distribution of both luminous and dark matter? Stellar dynamics provides one of the most direct and powerful tools to map the internal mass structure of galaxies. In this talk, I will present the MaNGA-DYNPOP project, which is based on the most comprehensive integral-field spectroscopic survey of nearby galaxies, SDSS-IV MaNGA. Using a sample of nearly ten thousand galaxies, we perform a systematic joint analysis of stellar dynamics and spatially resolved stellar populations. By combining Jeans Anisotropic Modelling (JAM) with spatially resolved stellar population synthesis, we reconstruct not only the distribution of stellar mass, but also the detailed total mass distribution, including dark matter. I will highlight several key results from this project: the emergence of scaling relations linking stellar population properties and dynamical structures, and how these relations evolve across galaxy types; precise measurements of the total mass density profiles in the inner regions of galaxies; the separation of stellar and dark matter components; and observational evidence for systematic variations of the stellar initial mass function (IMF) with galaxy properties. In addition, I will discuss how combining dynamical analyses with gravitational lensing enables us to extend these measurements to larger scales, probing the mass distribution in galaxy groups and clusters.

CV：Ran Li received his Ph.D. from Peking University in 2011. From 2011 to 2024 he worked at the National Astronomical Observatories, Chinese Academy of Sciences, serving as a postdoctoral researcher, associate researcher, and then researcher. Since 2024 he has been a Professor at the School of Physics and Astronomy, Beijing Normal University. His research interests include gravitational lensing, galaxy dynamics, and galaxy formation. Li has been involved in the Chinese Space Station Telescope (CSST) science program since 2010 and currently serves as the Responsible Scientist for Science Data at the Joint Center of Science for CSST. Beyond research, he writes for the public on science and is the author of Roaming the Universe.