(Published in ApJL 917 (2021) L15)

Dark Matter Deficient Galaxies And Their Member Star Clusters Form Simultaneously


We report a suite of galaxy collision simulations using the adaptive mesh refinement code Enzo with 1.25 pc resolution, which demonstrates that high-velocity galaxy collisions induce the formation of DMDGs and their star clusters (SCs) simultaneously. With numerical resolution significantly better than our previous study (80 pc in Shin et al. 2020), we resolve the dynamical structure of the produced DMDGs and the detailed formation history of their SCs which are possible progenitors of the DMDG’s member GCs. In particular, we show that a galaxy collision with a high relative velocity of ~ 300 km/s, invoking severe shock compression, spawns multiple massive SCs () within 150 Myr after the collision. At the end of our ~ 800 Myr fiducial run, the resulting DMDG of hosts 10 luminous (), gravitational bound SCs with a line-of-sight velocity dispersion 11.2 km/s. Our study suggests that DMDGs and their luminous member SCs could form simultaneously in high-velocity galaxy collisions while being in line with the key observed properties of NGC1052-DF2 and NGC1052-DF4.

We present movies of galaxy collision simulations with different configurations can result in DMDGs with comparable stellar mass of . For details of each run, please refer to Table 1 and Section 2 in our paper (Arxiv link). Movies listed below show seperation of baryons from dark matter and rapid star formation during galaxy collsion. We find that the physical properties of the produced DMDGs depend on the amount of gas participates in the supersonic collision, the strength of stellar feedback, initial gas metallicity, and the velocity shear in the colliding gas.

Movie of Fiducial run

Movies of simulation runs with different configurations (Table 1 and Figure 1 in the paper)
  1. Fiducial run
  2. FB3 run
  3. FB7 run
  4. FB10 run
  5. Low-metal run
  6. Retrograde run
  7. Tilt-1 run
  8. Tilt-1-FB10 run
  9. Tilt-2 run
  10. Tilt-2-FB10 run
Star clsuter zoomed-in movie (Figure 3 in the paper)

Fiducial run