  Ultra-light bosons such as axions or axion-like particles (ALPs), are
promising candidates to solve the dark matter problem. A unique way to detect
such ALPs is to search for the periodic oscillation feature of the position
angles of linearly polarized photons emitted from the regions where ALP dark
matter forms a solitonic core. In this work, we use the high-resolution
polarimetric measurements of the radiation near the super-massive black hole
(SMBH) in the center of the Milky Way, i.e., Sagittarius A$^\star$ (Sgr
A$^\star$), by a sub-array of the Event Horizon Telescope to search for the
ultra-light ALPs. We derive upper limits on the ALP-photon coupling of $\sim
10^{-12}{\rm GeV^{-1}}$ for ALP masses of $m\sim (10^{-19}-10^{-18})$eV. Our
results are stronger than that derived from the observations of SN1987A and a
population of supernovae in the mass window of ($10^{-19}-10^{-17}$)eV.
Improved polarimetric measurements with the full Event Horizon Telescope can
further strengthen the constraints.
