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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 consider two formation scenarios for such abnormal galaxies. The first one is that dark matter deficient galaxies might be a remnant of violent galaxy interactions. As the 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 the key observations, such as the extremely low dark matter mass, 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. Another scenario to be considered is that dark matter deficient galaxies might have been originated from a collision of two gas-rich dwarf galaxies. Based on the theoretical modeling of the orbital evolution of globular clusters in dark matter deficient galaxies and their susceptibility against the tidal force of the host galaxy, we find that the scenario has difficulties in explaining the extended distribution and number of globular clusters in the dark matter deficient galaxies.
Go Ogiya is a tenure-track faculty member at Zhejiang University since 2022. Before coming to China, he received his Ph.D. from the University of Tsukuba in Japan and held postdoc positions at the Max Planck Institute for Extraterrestrial Physics in Germany, Observatoire de la Côte d'Azur in France, and the University of Waterloo in Canada. His research interest spans a wide range of astrophysics, from the smallest dark matter halos to the largest galaxy clusters, and of numerical computation, including developing high-performance simulation codes and machine learning.
Place: N630
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