Probing the Fermi-LAT GeV Excess with Gravitational Waves

Area of Science:

• Astrophysics
• Cosmology
• Particle Physics

Background:

• The Fermi-LAT satellite has detected an excess of gamma-rays from the inner Milky Way (Galactic Center Excess - GCE).
• Millisecond pulsars (MSPs) are a leading candidate source for the GCE, but this hypothesis requires confirmation.

Purpose of the Study:

• To investigate the potential gravitational wave (GW) signal associated with the Galactic Center Excess (GCE) if it originates from millisecond pulsars (MSPs).
• To estimate the sensitivity of current and future gravitational wave detectors to this predicted signal.

Main Methods:

• Modeling the expected GW emission from a population of bulge MSPs, informed by fits to the Fermi-LAT GCE data.
• Calculating the projected sensitivity reach of terrestrial GW detectors (LIGO/Virgo and third-generation detectors) for GW signals from MSP populations.

Main Results:

• The GW signal from bulge MSPs is predicted to be an order of magnitude stronger than that from disk MSPs.
• Achievable sensitivity with 10 years of LIGO/Virgo data could constrain the average population ellipticity to ϵ ≃ 10^{-7}.
• Future third-generation GW detectors could reach sensitivities of ϵ ≃ 10^{-8}.

Conclusions:

• The predicted GW signal provides a powerful tool to test the MSP interpretation of the GCE.
• Gravitational wave astronomy offers a complementary observational window to gamma-ray astronomy for investigating high-energy astrophysical phenomena.