Spatial extension of dark subhalos as seen by Fermi -LAT and the implications for WIMP constraints

• Main Authors: (Fermi -LAT Collaboration) (Author), Aguirre-Santaella, A. (Author), Coronado-Blázquez, J. (Author), Pérez-Romero, J. (Author), Sánchez-Conde, M.A (Author)
• Format: Article
• Language: English
• Published: American Physical Society 2022
• Online Access: View Fulltext in Publisher

 Spatial extension has been hailed as a "smoking gun"in the gamma-ray search of dark galactic subhalos, which would appear as unidentified sources for gamma-ray telescopes. In this work, we study the sensitivity of the Fermi-LAT to extended subhalos using simulated data based on a realistic sky model. We simulate spatial templates for a set of representative subhalos, whose parameters were derived from our previous work with N-body cosmological simulation data. We find that detecting an extended subhalo and finding an unequivocal signal of angular extension requires, respectively, a flux 2 to 10 times larger than in the case of a pointlike source. By studying a large grid of models, where parameters such as the WIMP mass, annihilation channel, or subhalo model are varied significantly, we obtain the response of the LAT as a function of the product of annihilation cross-section times the J factor. Indeed, we show that spatial extension can be used as an additional "filter"to reject subhalos candidates among the pool of unidentified LAT sources, as well as a smoking gun for positive identification. For instance, typical angular extensions of a few tenths of a degree are expected for the considered scenarios. Finally, we also study the impact of the obtained LAT sensitivity to such extended subhalos on the achievable dark matter constraints, which are a few times less constraining than comparable point-source limits. © 2022 American Physical Society.