摘要:
   We report the detection of a 219 $^{+10}_{-28}$ pc-sized dark matter core structure in the center of Milky Way at one sigma level by using the micro-lensing event rate sky map data from OGLE survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way structure, the Mini Dark Matter Structure (MDMS) fraction ($f_{\rm MDMS}=\Omega_{\rm MDMS}/\Omega_{\rm DM}$) and the core size.     We find that this sky map can constrain both $f_{\rm MDMS}$ and the core size simultaneously without strong degeneracy. This discovery not only provides a vital guidance for dark matter particle models, namely self-interacting dark matter (SIDM), the baryonic feedback of Milky Way, but also can potentially provide extra inner density profile to break the degeneracy between the density profile and the Hubble constant derived from strong lensing time delay observations.