  Observations of the velocity dispersion indicate a severe dark matter (DM)
deficit in the ultra-diffuse galaxy, NGC1052-DF4 (DF4). The ultra-deep images
obtained with the Gemini telescope, which has the deepest imaging data till
now, confirm the presence of tidal tails in DF4, suggesting its tidal
formation. To enhance tidal effects, we consider the self-interaction among DM
particles. Using an N-body simulation in the scenario of self-interacting dark
matter (SIDM), we reproduce a DM-deficient galaxy that is consistent with all
observational data of DF4. Specifically, our simulation result yields an
extremely low DM-to-star mass ratio and a radial surface brightness profile
very similar to that from deep images, showing accurate tidal features. By
performing simulations with similar tidal effects and various cross-sections of
SIDM, we show a significant impact of SIDM on the DM-to-star mass ratio in the
central region of the galaxy. Our work confirms the tidal formation of DF4 in
theory.
