Nearby dwarf spheroidal galaxies are ideal targets in the search for indirect dark matter (DM) signals. In this work, we analyze MUSE spectroscopic observations of a sample of five galaxies, composed of both classical and ultra-faint dwarf spheroidals. The goal is to search for radiative decays of axion-like particles (ALPs) in the mass range of 2.7–5.3 eV. After taking into account the uncertainties associated with the DM spatial distribution in the galaxies, we derive robust bounds on the effective ALP-two-photon coupling. They lie well below the QCD axion band and are significantly more constraining than limits from other probes, in the relevant mass range. We also test the possible presence of a positive signal, concluding that none of the wavelength channels selected for this analysis, i.e., not affected by large background contamination, is exhibiting such evidence.

中文翻译：

---

光学 MUSE-Faint 巡天中矮球状星系 ALP 暗物质的稳健界限

附近的矮球状星系是寻找间接暗物质（DM）信号的理想目标。在这项工作中，我们分析了由经典和超微弱矮球体组成的五个星系样本的 MUSE 光谱观测结果。目标是寻找质量范围为 2.7-5.3 eV 的轴子粒子 (ALP) 的辐射衰变。在考虑到与星系中 DM 空间分布相关的不确定性后，我们得出了有效 ALP-双光子耦合的稳健界限。它们远低于 QCD 轴子带，并且在相关质量范围内比其他探针的限制明显更具约束力。我们还测试了可能存在的正信号，得出的结论是，为该分析选择的波长通道（即不受大背景污染影响的波长通道）都没有表现出这样的证据。