Uncovering dark matter distributions: from the Milky Way to nearby galaxies
by
Tsung-Dao Lee Institute/N6F-N601 - Meeting Room
Tsung-Dao Lee Institute
Host: Dong Lai
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Abstract:
Dark matter distribution in galaxies is a key to test the ΛCDM and galaxy formation models. We measure the dark-matter distribution for a representative sample of 130 nearby galaxies by combining IFU data from MaNGA and HI spectra from FAST. We find strong evidence that these galaxies exhibit a lower dark-matter fraction in their inner regions than predicted by all the widely accepted cosmological simulations EAGLE, TNG and Simba. Compared to these simulations, there is a dark-matter deficit core, with the core size increasing from about 10 kpc to 50 kpc for galaxies with stellar masses ranging from 5e9 to 3e11 M⊙. These results suggest that important pieces of physics are missing in current Hydrodynamical simulations. In the case of the MW, we find a similar dark-matter deficit core; more interestingly, we have managed to precisely determine the 3D shape of its dark-matter halo. Unexpectedly, the MW dark-matter halo is vertical to the stellar disc and in alignment with the prominent satellite plane. Such striking configuration is rare but not an outlier in the cosmological simulations, they suggests a flip of the Galactic disc caused by minor mergers.
Biography:
My research focuses on galactic structures and dynamics. I have led a research group in Shanghai Astronomical Observatory (中国科学院上海天文台) since 09/2018. Before joining SHAO, I was a postdoc researcher at the Max Planck Institute for Astronomy, Heidelberg, Germany (德国马普天文所) from 2013-2018. I got my Ph.D. degree at the Center for Astrophysics, Tsinghua University (清华大学天体物理中心) in 2013. I obtained my Bachelor's degree from Department of Physics, Tsinghua University, Beijing (清华大学物理系) in 2008.
