Self-interacting dark matter (SIDM) has gathered growing attention as a solution to the small-scale problems of the collisionless cold dark matter (CDM). We investigate the SIDM using stellar kinematics of the 23 ultra-faint dwarf (UFD) galaxies with the phenomenological SIDM halo model. The UFDs are DM-dominated and have less active star formation history. Therefore, they are the ideal objects to test the SIDM, as their halo profiles are hardly affected by the baryonic processes. We found no UFDs favor nonzero self-interaction and some provide stringent constraints. Our result challenges the simple halo modeling of the SIDM, which urges further investigation of the subhalo dynamical evolution of the SIDM.

• Received 24 August 2020
• Revised 30 October 2020
• Accepted 22 December 2020

DOI:https://doi.org/10.1103/PhysRevD.103.023017