Speaker
Description
Recent observations revealed that the dark matter mass contained in two ultra diffuse galaxies in the vicinity of an elliptical galaxy, NGC 1052, is several hundred times lower than the predictions by the theoretical models of galaxy formation and evolution. The dynamics of the galaxies is described by only the gravity of stars. As such dark matter deficient galaxies can be a challenge for the current understanding of galaxy formation and evolution, they have attracted attention from astrophysicists and have been investigated intensively. In this talk, we first consider a formation scenario that dark matter deficient galaxies might be a remnant of violent galaxy interactions. As dark matter is less tightly bound than stars, the gravity of NGC1052 preferentially strips the dark matter mass from a satellite galaxy, transforming a normal satellite galaxy into a dark matter deficient galaxy. Numerical simulations of the interaction between NGC1052 and a possible progenitor of dark matter deficient galaxies reproduce well key observations, such as the mass profile, the effective radius, and the distribution of globular clusters. Therefore, dark matter deficient galaxies can be a remnant of a violent mass-loss event and be explained within the standard framework of cosmic structure formation. We will also consider another scenario that dark matter deficient galaxies might have been originated from a collision of two gas-rich dwarf galaxies, and find that it has difficulties in explaining the extended distribution and number of globular clusters in the galaxies.
