# Probing the Fermi-LAT GeV excess with gravitational waves

## TL;DR

This paper explores the potential gravitational wave signals from millisecond pulsars in the Galactic bulge as an explanation for the gamma-ray excess, assessing detectability with current and future GW detectors.

## Contribution

It provides the first estimates of gravitational wave signals associated with the Galactic Center excess and evaluates the sensitivity of GW detectors to these signals.

## Key findings

- Current GW detectors could detect signals if pulsar ellipticity is around 10^{-7}.
- Future detectors could reach sensitivities for ellipticity as low as 10^{-8}.
- Detection would provide crucial evidence for the MSP origin of the gamma-ray excess.

## Abstract

If the gamma-ray excess towards the inner Galaxy (GCE) detected in Fermi-LAT data is due to millisecond pulsars (MSPs), one expects an associated gravitational wave (GW) signal, whose intensity exceeds the disk MSP population emission by an order of magnitude. We compute the expected GW counterpart of the bulge MSP population based on fits of the GCE, and estimate the sensitivity reach of current and future terrestrial GW detectors. The bounds on the average population ellipticity $\varepsilon$ are competitive with the existing ones derived by LIGO/Virgo towards known MSPs. With a 10-year data taking in current LIGO/Virgo configuration, one would detect a signal at the level $\varepsilon\simeq 10^{-7}$, while $\varepsilon\simeq 10^{-8}$ would be attainable with a similar data taking period with a third generation GW detector. This sensitivity should be sufficient for crucial diagnostics on the GCE interpretation in terms of MSPs.