Probing the millisecond pulsar origin of the $\gamma$-ray excess in the Galactic centre with LISA

Abstract

The gigaelectronvolt $\gamma$-ray excess observed towards the Galactic centre remains unexplained. While dark matter annihilation has long been considered a leading explanation, an alternative scenario involving a large population of millisecond pulsars remains viable. Testing this hypothesis with electromagnetic observations is difficult, as pulsar searches in the bulge are strongly affected by interstellar scattering, high sky temperature, and source confusion. We investigate whether gravitational-wave observations with the Laser Interferometer Space Antenna (LISA) could provide an independent probe of the millisecond pulsar binary population in the Galactic bulge in the future. We constructed synthetic populations of detached millisecond pulsar-white dwarf binaries under two illustrative formation scenarios: an accreted scenario, in which systems are deposited by disrupted globular clusters, and an in situ scenario, in which binaries form through isolated binary evolution. In both cases, only $10^{-5}$-$10^{-4}$ of the underlying bulge population is detectable by LISA. Still, even a few detections would imply tens to hundreds of thousands of unseen systems. Accreted binaries are expected to have lower chirp masses ($\sim$0.4 M${}_{\odot }$), while in situ binaries produce more massive companions ($\sim$0.9 M${}_{\odot }$), though part of this contrast reflects our modelling assumptions. LISA will measure binary frequencies with high precision, but chirp masses can only be determined for the most massive or highest-frequency systems. Thus, identifying millisecond-pulsar binaries among the far more numerous double white dwarfs will be challenging, as their gravitational-wave signals alone are indistinguishable. However, coordinated follow-up with the Square Kilometre Array of LISA-selected targets could directly test the millisecond-pulsar explanation of the $\gamma$-ray excess.

References in corpus (44)

• Background model systematics for the Fermi GeV excess
• Post-common-envelope binaries from SDSS. IX: Constraining the common-envelope efficiency
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• The observed velocity distribution of young pulsars
• GeV excess in the Milky Way: The Role of Diffuse Galactic gamma ray Emission template
• The formation of low-mass helium white dwarfs orbiting pulsars: Evolution of low-mass X-ray binaries below the bifurcation period
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: comparison with the SDSS DR7 observed sample
• Mass transfer in white dwarf-neutron star binaries
• The Globular Cluster Migratory Origin of Nuclear Star Clusters
• Discovery of two pulsars towards the Galactic Centre
• The observed velocity distribution of young pulsars II: analysis of complete PSR$\pi$
• Detecting Double Neutron Stars with LISA
• Narrowband searches for continuous and long-duration transient gravitational waves from known pulsars in the LIGO-Virgo third observing run
• Nitrogen enrichment and clustered star formation at the dawn of the Galaxy
• Can Astrophysical Gamma Ray Sources Mimic Dark Matter Annihilation in Galactic Satellites?
• Formation of millisecond pulsars with helium white dwarfs, ultra-compact X-ray binaries and gravitational wave sources
• Modelling the formation of double white dwarfs
• Monte Carlo simulations of post-common-envelope white dwarf + main sequence binaries: The effects of including recombination energy
• The Gamma-Ray Pulsar Population of Globular Clusters: Implications for the GeV Excess
• Gravitational wave sources in our Galactic backyard: Predictions for BHBH, BHNS and NSNS binaries detectable with LISA
• Identifying LISA verification binaries among the Galactic population of double white dwarfs
• Millisecond Pulsars from Accretion Induced Collapse as the Origin of the Galactic Centre Gamma-ray Excess Signal
• Combined analysis of neutron star natal kicks using proper motions and parallax measurements for radio pulsars and Be X-ray binaries
• Deep Einstein@Home all-sky search for continuous gravitational waves in LIGO O3 public data
• Ultra-compact X-ray binaries with He star companions
• Novel modelling of ultra-compact X-ray binary evolution - stable mass transfer from white dwarfs to neutron stars
• Black widow evolution: magnetic braking by an ablated wind
• UltraCompCAT: a comprehensive Catalogue of Ultra-Compact and Short Orbital Period X-ray Binaries
• Continuous gravitational waves from Galactic neutron stars: demography, detectability and prospects
• Stars stripped in binaries -- the living gravitational wave sources
• Was the Milky Way Bulge Formed From The Buckling Disk Instability, Hierarchical Collapse, Accretion of Clumps, or All of the Above?
• The age distribution of stars in the Milky Way bulge
• A population of compact radio variables and transients in the radio bright zone at the Galactic center observed with the Jansky Very Large Array
• Catalogue of model star clusters in the Milky Way and M31 galaxies
• A pulsar-helium star compact binary system formed by common envelope evolution
• Detection of a dense group of hyper-compact radio sources in the central parsec of the Galaxy
• How can LISA probe a population of GW190425-like binary neutron stars in the Milky Way?
• The High Time Resolution Universe Pulsar Survey -- XVIII. The reprocessing of the HTRU-S Low Lat survey around the Galactic centre using a Fast Folding Algorithm pipeline for accelerated pulsars
• Expected insights on type Ia supernovae from LISA's gravitational wave observations
• A New Determination of the Millisecond Pulsar Gamma-Ray Luminosity Function and Implications for the Galactic Center Gamma-Ray Excess
• Discovering neutron stars with LISA via measurements of orbital eccentricity in Galactic binaries
• Natal kicks of compact objects
• The effects of Galactic model uncertainties on LISA observations of double neutron stars
• On the Gravitational Wave Counterpart to a Gamma-ray Galactic Center Signal from Millisecond Pulsars