Binary Neutron Stars from the Moon: Early Warnings and Precision Science for the Artemis Era

TL;DR

The paper shows that lunar gravitational-wave observatories (LGWA, GLOC, LILA) envisioned for NASA's Artemis era can provide weeks-to-months of early warning and arcsecond-level sky localization for binary neutron star mergers, far surpassing Earth-based detectors. Using Fisher-matrix-based parameter estimation with a GW170817-like fiducial system, the authors quantify horizon distances, localization accuracies, and annual detection rates for Moon-only and Earth–Moon networks across 2G/3G configurations. They find that multi-band Earth–Moon networks yield dramatically tighter constraints on the chirp mass, mass ratio, spins, tidal deformability, and luminosity distance, enabling precise measurements of the neutron-star equation of state and the Hubble constant, with mass-ratio uncertainties around ~0.1% and D_L errors near ~1%. The results imply a revolutionary leap in multi-messenger astrophysics, offering hundreds of well-localized BNS detections per year and a discovery landscape that complements and extends terrestrial facilities in the Artemis era.

Abstract

Binary neutron star mergers are unique probes of matter at extreme density and standard candles of cosmic expansion. The only such event observed in both gravitational waves and electromagnetic radiation, GW170817, revealed the origin of heavy elements, constrained the neutron star equation of state, and provided an independent measurement of the Hubble constant. Current detectors such as LIGO, Virgo, and KAGRA capture only the final minutes of inspiral, offering limited advance warning and coarse sky localization. In this study, we present a comprehensive analysis of binary neutron star signals for lunar-based gravitational-wave observatories (LILA, LGWA, GLOC) envisioned within NASA's Artemis and Commercial Lunar Payload Services programs, and compare their performance with current and next-generation Earth-based facilities. For GW170817-like sources, we find that lunar detectors can forecast mergers weeks to months in advance and localize them to areas as small as 0.01 deg$^{2}$, far beyond the reach of terrestrial detectors. We further show that lunar observatories would detect on the order of 100 well-localized mergers annually, enabling coordinated multi-messenger follow-up. When combined in a multi-band LIGO+Moon network, sky-localization areas shrink to just a few arcsec$^{2}$, comparable to the field of view of the James Webb Space Telescope at high zoom. Multi-band parameter estimation also delivers dramatic gains: neutron star mass-ratio uncertainties can be measured with $\sim0.1\%$ precision, spin constraints to 0.001$\%$ with luminosity distance errors to 1$\%$ level, enabling precision measurements of the equation of state and the cosmic expansion rate. Our results demonstrate that lunar gravitational-wave observatories would revolutionize multi-messenger astrophysics with binary neutron stars and open a unique discovery landscape in the Artemis era.

Figures (6)

• Figure 1: Sensitivity curves of various detectors, along with GW strain of a GW170817-like signal with annotated times to merger.
• Figure 2: SNR evolution to merger as a function of time (in hours). The black dashed line at SNR=8 shows the threshold that is generally used to claim a GW detection.
• Figure 3: Horizon distance of a GW170817-like system as a function of time to merger in hours, for a threshold of SNR=8 (solid curve) and SNR=30 (dashed curve). The gray dotted line denotes the reported luminosity distance of GW170817 (40 Mpc).
• Figure 4: 90$\%$ CI of the sky location errors ($\Delta\Omega$) for a GW170817-like system at luminosity distance of 40 Mpc, observed in Lunar-SEI at 1 month pre-merger (shaded region in the left inset near the marker), Lunar-SUS at 1 day pre-merger, ET at 6 hours pre-merger along with HLV sky localization of the real event (includes the complete observed inspiral signal).
• Figure 5: 90$\%$ CI of the sky location errors ($\Delta\Omega$) of a GW170817-like system at a luminosity distance of 40 Mpc, as a function of time to merger in hours. Note this is the early warning alert sky localization.