The extragalactic background light is comprised of the cumulative radiation from all galaxies across the history of the universe. The angular power spectrum of the anisotropies of such a background at near-infrared (IR) frequencies lacks of a complete understanding and shows a robust excess which cannot be easily explained with known sources. Dark matter in the form of axion-like particles (ALPs) with a mass around the electronvolt will decay into two photons with wavelengths in the near-IR band, possibly contributing to the background intensity. We compute the near-IR background angular power spectrum including emissions from galaxies, as well as the contributions from the intra-halo light and ALP decay, and compare it to measurements from the Hubble Space Telescope and Spitzer. We find that the preferred values for the ALP mass and ALP-photon coupling to explain the excess are in tension with star cooling data and observations of dwarf spheroidal galaxies.

河外背景光由宇宙历史上所有星系的累积辐射组成。这种背景在近红外 (IR) 频率下的各向异性的角功率谱缺乏完整的理解，并显示出强大的过剩，这无法用已知来源轻松解释。质量在电子伏附近的类轴子粒子 (ALP) 形式的暗物质将衰变为两个波长在近红外波段的光子，这可能会影响背景强度。我们计算了近红外背景角功率谱，包括来自星系的发射，以及来自晕内光和 ALP 衰变的贡献，并将其与哈勃太空望远镜和斯皮策的测量结果进行比较。