2025/06/25 by Yupeng Yang, Q.Z. Li, Yang, Yupeng +5
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2506.20391
openalex publication_date 2025/06/25 · openalex created_date 2025/10/09 · openalex updated_date 2026/07/28
The lightest Kaluza-Klein (KK) dark matter particles and primordial black holes (PBHs) emerge as plausible candidates for dark matter. In scenarios where dark matter is a mix of KK particles and PBHs, PBHs can attract surrounding KK dark matter particles post-formation, leading to the creation of ultracompact dark matter halos (UCMHs). The distribution of KK dark matter particles within UCMHs tends to be steeper than in classical dark matter halo structures, such as the Navarro-Frenk-White model. Consequently, the annihilation rate of KK dark matter particles in UCMHs is significant. The high-energy photons resulting from the annihilation of KK particles in UCMHs contribute to the extragalactic gamma-ray background (EGB). Leveraging data from the \mathttFermi-LAT experiment, we have derived, for the first time, upper limits on the cosmological abundance of PBHs in the context of KK dark matter annihilation. For a KK dark matter mass range of 500≤ m\rm B(1)≤ 1500 GeV, which aligns with the observed present abundance of dark matter, the conservative limits on the fraction of dark matter in PBHs, for massive PBHs with M\rm PBH\gtrsim 10-11M\odot, are f\rm PBH \lesssim 2× 10-5.