# Inverse Compton emission from millisecond pulsars in the Galactic bulge

## TL;DR

This paper models inverse Compton gamma-ray emissions from millisecond pulsars in the Galactic bulge, comparing different spatial distributions to help identify their contribution to the observed GeV excess.

## Contribution

It introduces a detailed GALPROP-based calculation of IC emissions from MSPs using a triaxial bulge model, highlighting spatial morphology differences for future detection.

## Key findings

- Spectra are similar for different MSP spatial models
- Spatial morphology features can distinguish MSP origins
- High-energy IC emissions can inform MSP distribution models

## Abstract

Analyses of Fermi Gamma-Ray Space Telescope data have revealed a source of excess diffuse gamma rays towards the Galactic center that extends up to roughly $\pm$20 degrees in latitude. The leading theory postulates that this GeV excess is the aggregate emission from a large number of faint millisecond pulsars (MSPs). The electrons and positrons ($e^\pm$) injected by this population could produce detectable inverse-Compton (IC) emissions by up-scattering ambient photons to gamma-ray energies. In this work, we calculate such IC emissions using GALPROP. A triaxial three-dimensional model of the bulge stars obtained from a fit to infrared data is used as a tracer of the putative MSP population. This model is compared against one in which the MSPs are spatially distributed as a Navarro-Frenk-White squared profile. We show that the resulting spectra for both models are indistinguishable, but that their spatial morphologies have salient recognizable features. The IC component above $\sim$TeV energies carries information on the spatial morphology of the injected $e^\pm$. Such differences could potentially be used by future high-energy gamma-ray detectors such as the Cherenkov Telescope Array to provide a viable multiwavelength handle for the MSP origin of the GeV excess.