SIMBAD references

Recent advances in photon detectors have provided exceptional sensitivities to dark matter with high angular resolution. Motivated by this, we present a detailed study of photon flux from dark matter decay in dwarf spheroidal galaxies (dSphs) by focusing on the detectors with arcsecond-level field of view and/or angular resolution. We propose to use differential D-factors since such detectors are sensitive to their dark matter distributions. We carefully estimate the differential D-factors of 35 dSphs. By using the differential D-factors, it turns out that the resulting signal flux can have a more than ${ \mathcal O }$(1-10) enhancement compared to conventional estimations. Based on this analysis, we find that the Infrared Camera and Spectrograph (IRCS) installed on the 8.2 m Subaru Telescope can be an excellent dark matter detector for the mass in the eV range, particularly axion-like particles (ALPs). Observing the Draco or Ursa Major II dSphs with the IRCS for ${ \mathcal O }(1)$ night will enable us to place the most stringent bound for the ALP dark matter in the mass range of 1 eV ≲ m_a ≲ 2 eV.