# Limits on Dark Matter annihilation cross sections to gamma-ray lines with subhalo distribution in N-body simulation and Fermi LAT data

## TL;DR

This study combines N-body simulation data of dark matter subhalos with Fermi LAT gamma-ray observations to set new constraints on dark matter annihilation cross sections to gamma-ray lines, emphasizing the role of low-mass subhalos.

## Contribution

It is the first work to integrate numerical subhalo simulations with Fermi LAT data to constrain dark matter annihilation cross sections to gamma-ray lines.

## Key findings

- Low-mass subhalos significantly contribute to total J-factors.
- Constraints from subhalo populations are weaker but complementary to Galactic center observations.
- The combined approach provides new bounds on dark matter annihilation cross sections.

## Abstract

In this work, we simulate a set of realizations of local volume dark matter subhalo population based on the distributions and relations derived from Via Lactea II N-body simulation. We calculate the J-factors of these subhalos, and find that the low mass subhalos contribute a lot to the total J-factors. Combining with 91 months of the Fermi LAT observation, we constrain on the cross section of dark matter annihilating directly to two gamma rays. This is the first work combining numerical simulation results and Fermi LAT observations to constrain dark matter cross section to gamma-ray line with subhalo population. Though the constraints derived from subhalo population are weaker than those from Fermi LAT observation of the Galactic center, they are supports of and complementary to these other results.