We're very pleased to have Dr. Wenting WANG （王文婷）from Shanghai Jiaotong University to give an on-line colloquium talk next Monday (Dec. 28th). The title and abstract of the talk are shown below. You can either participate on line via tencent meeting system
or join us at C134. The information of the on-line meeting system will be given after the talk information.
Title: Low-mass satellite galaxies and faint diffuse stellar halos of isolated galaxies
In the standard structure formation paradigm of LambdaCDM, galaxies form at the centers of dark matter halos. Smaller galaxies and their host halos can merge with larger halos, becoming the so-called satellite galaxies and subhalos. Orbiting around the central dominant galaxy of the host halo and undergoing tidal stripping, these satellites and subhalos lose their mass, which form stellar streams and the diffuse stellar halos around the central galaxies.
Low-mass satellite galaxies are one of the most effective tools to distinguish different dark matter models, but previous studies on such low-mass satellites are often focused within our Milky Way and the Local Group. The study of distant low-mass satellites is difficult because they often lack in spectroscopic distance measurements. We have developed a statistical method of counting faint photometric satellites around spectroscopically identified bright isolated central galaxies, and the method has been applied to three different surveys (HSC, DECaLS and SDSS). In this talk, I will introduce the properties of these faint satellites and the connection to their central galaxy properties and the host dark matter halo mass. There are evidences that red and high-concentration galaxies have more satellites and are hosted by more massive dark matter halos. These extra-galactic satellites are compared with our Milky Way satellites, indicating our Milky Way system is statistically atypical.
In the second part of the talk, I will introduce our efforts of investigating the faint diffuse stellar halos for isolated central galaxies, by stacking galaxy images from HSC. After PSF corrections, we found the surface brightness profiles of central galaxies and their stellar halos are close to universal after scaled by the halo virial radius. High-concentration galaxies (mostly red) have more extended stellar halos, redder and shallower color profiles. Satellites of red centrals are also redder. The results can be understood in the stardard cosmological context that red galaxies formed early but stop forming stars at late times, while their host halos, population of satellites and outer stellar halos keep growing through accretion.