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The new generation lunar gravitational wave detectors: sky map resolution and joint analysis

Xiaolin Zhang, Chengye Yu, Haoran Li, Sobhan Kazempour, Mingqiu Li, Sichun Sun

TL;DR

This work addresses bridging the deci-Hertz gap in gravitational-wave astronomy by assessing lunar-based CIGO designs using a Fisher Information Matrix (FIM) framework. It models the detector response and lunar geometry to quantify sky-localization accuracy for monochromatic signals across the 0.1–10 Hz band, comparing CIGO with LISA and TianQin and exploring a tetrahedral augmentation (TCIGO). The results show that CIGO dominates angular localization above 0.1 Hz, with joint networks offering gains at the low-frequency end, while lunar seismic noise can limit performance in the 0.1–2.87 Hz range unless more advanced noise mitigation is implemented; TCIGO can boost angular resolution by about a factor of 5 and provide complete sky coverage. Overall, the lunar platform emerges as a viable, serviceable bridge between space-based and ground-based GW observatories, guiding future design choices for mid-frequency GW detection.

Abstract

Lunar-based gravitational-wave interferometry is a fascinating endeavor, and was proposed as a promising approach to bridge the observational gap between space-borne and ground-based detectors. In this work, we adopt the Fisher-matrix method to examine the angular-resolution performance of the newly proposed Crater Interferometry Gravitational-wave Observatory (CIGO) on the lunar crater rim near the north pole, together with TianQin and LISA, for monochromatic sources in the 0.1-10 Hz band. We find that above 0.1 Hz, CIGO achieves better localization accuracy than the other two space-based missions and dominates the combined detector network's performance, provided that lunar noise mitigation is achieved in the 0.1-2.87 Hz frequency range. We further explore an upgraded Tetrahedron configuration, TCIGO, with a fourth station at the bottom of a crater, which forms a regular tetrahedral constellation on the lunar surface. The result shows that TCIGO yields a five-fold improvement in angular-resolution capability over CIGO and gets better sky coverage across the target frequency band.

The new generation lunar gravitational wave detectors: sky map resolution and joint analysis

TL;DR

This work addresses bridging the deci-Hertz gap in gravitational-wave astronomy by assessing lunar-based CIGO designs using a Fisher Information Matrix (FIM) framework. It models the detector response and lunar geometry to quantify sky-localization accuracy for monochromatic signals across the 0.1–10 Hz band, comparing CIGO with LISA and TianQin and exploring a tetrahedral augmentation (TCIGO). The results show that CIGO dominates angular localization above 0.1 Hz, with joint networks offering gains at the low-frequency end, while lunar seismic noise can limit performance in the 0.1–2.87 Hz range unless more advanced noise mitigation is implemented; TCIGO can boost angular resolution by about a factor of 5 and provide complete sky coverage. Overall, the lunar platform emerges as a viable, serviceable bridge between space-based and ground-based GW observatories, guiding future design choices for mid-frequency GW detection.

Abstract

Lunar-based gravitational-wave interferometry is a fascinating endeavor, and was proposed as a promising approach to bridge the observational gap between space-borne and ground-based detectors. In this work, we adopt the Fisher-matrix method to examine the angular-resolution performance of the newly proposed Crater Interferometry Gravitational-wave Observatory (CIGO) on the lunar crater rim near the north pole, together with TianQin and LISA, for monochromatic sources in the 0.1-10 Hz band. We find that above 0.1 Hz, CIGO achieves better localization accuracy than the other two space-based missions and dominates the combined detector network's performance, provided that lunar noise mitigation is achieved in the 0.1-2.87 Hz frequency range. We further explore an upgraded Tetrahedron configuration, TCIGO, with a fourth station at the bottom of a crater, which forms a regular tetrahedral constellation on the lunar surface. The result shows that TCIGO yields a five-fold improvement in angular-resolution capability over CIGO and gets better sky coverage across the target frequency band.
Paper Structure (15 sections, 29 equations, 8 figures, 2 tables)

This paper contains 15 sections, 29 equations, 8 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Fisher Information Matrix Method
  3. General GW Signal and Response in GR
  4. Lunar detector orbit and detector tensor
  5. CIGO Fisher Information Matrix Method
  6. Source Localization
  7. Tetrahedron Form of CIGO
  8. Conclusion
  9. Derivation of the Detector Position in the Heliocentric--Ecliptic Coordinate System
  10. Detector position in the lunar-centered frame
  11. Lunar orbital motion in the geocentric--lunar frame
  12. Earth’s orbital motion in the heliocentric--ecliptic frame
  13. Rotation from the lunar orbital plane to the ecliptic plane
  14. Total detector position in the heliocentric--ecliptic frame
  15. Modification of lunar base noise parameters based on the pygwinc CE1 project

Figures (8)

  • Figure 1: Schematic diagram of CIGO's orbit and coordinate system.
  • Figure 2: The sky map of angular resolutions $\Delta \Omega_S$ of sources from different directions in the unit of steradian (1 steradian is 3000 square degrees) for LISA, Tianqin, CIGO, and their network. The horizontal axis represents the longitude $\phi_s$ and the vertical axis represents the latitude $\theta_s$. The frequencies of monochromatic sources are $0.1$ Hz, $1$ Hz, and $10$ Hz.
  • Figure 3: Cumulative histograms of sky localization estimations $\Delta \Omega_S$ for different detectors
  • Figure 4: Noise level estimation of CIGO
  • Figure 5: Cumulative histograms of sky localization estimations $\Delta \Omega_S$ considering the lunar noise
  • ...and 3 more figures