On the Gamma-Ray Signals from UCMH/mini-spike Accompanying the DAMPE 1.4 TeV E+e− Excess

The tentative 1.4 TeV e+e− excess observed by DAMPE, if not a statistical fluctuation, may be explained by dark matter (DM) annihilation within a nearby subhalo with a distance of <0.3 kpc. The process of DM annihilating to e+e− is accompanied by the production of gamma-ray photons, which could lead to detectable signals of Fermi-LAT. In this work, we focus on the model that the tentative 1.4 TeV signal is from a nearby ultracompact mini halo (UCMH). Due to the small angular extension, the counterpart gamma-ray signal would be hidden among Fermi-LAT unassociated point sources. We examine the point sources in 4FGL systematically by analyzing the Fermi-LAT data, aiming to investigate whether there exist sources with gamma-ray properties consistent with the UCMH model of the 1.4 TeV excess. We find more than 10 sources could be the candidates. Furthermore, we test the possibility that the excess signal is from a DM mini-spike around the nearest BH, but our result does not favour such a scenario.