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| Main Authors: | , |
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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2604.23384 |
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| _version_ | 1866914516101496832 |
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| author | Han, Jing-Hong Zhao, Zhi-Chao |
| author_facet | Han, Jing-Hong Zhao, Zhi-Chao |
| contents | We develop a full-covariance formalism for pulsar timing array(PTA) -- astrometry verlap reduction function (ORF) estimators and use it to forecast graviton-mass constraints from a nanohertz stochastic gravitational-wave background (SGWB). Analytic covariance expressions are derived for auto- and cross-channel ORF estimators, including signal-signal, noise-noise, and signal-noise contributions, and are validated against numerical simulations. For an observational configuration with sensitivities comparable to NANOGrav and Gaia, we obtain an expected joint 90\% upper limit of $m_g<4.41\times10^{-24}\,\mathrm{eV}/c^2$, which remains PTA-dominated and lies at the same order of magnitude as the existing NANOGrav 15-year PTA-only bound. For a future-like configuration with sensitivities comparable to the SKA and Theia/Gaia-NIR, the astrometric channels contribute significantly to the constraining power, and the joint limit improves to $m_g<0.48 \times 10^{-24} \, \mathrm{eV}/c^2$. These forecasts indicate that PTA -- astrometry multichannel inference provides a viable avenue for improving graviton-mass constraints under next-generation observational conditions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_23384 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Forecasting graviton-mass constraints from the full covariance of PTA-astrometry ORF estimators Han, Jing-Hong Zhao, Zhi-Chao General Relativity and Quantum Cosmology We develop a full-covariance formalism for pulsar timing array(PTA) -- astrometry verlap reduction function (ORF) estimators and use it to forecast graviton-mass constraints from a nanohertz stochastic gravitational-wave background (SGWB). Analytic covariance expressions are derived for auto- and cross-channel ORF estimators, including signal-signal, noise-noise, and signal-noise contributions, and are validated against numerical simulations. For an observational configuration with sensitivities comparable to NANOGrav and Gaia, we obtain an expected joint 90\% upper limit of $m_g<4.41\times10^{-24}\,\mathrm{eV}/c^2$, which remains PTA-dominated and lies at the same order of magnitude as the existing NANOGrav 15-year PTA-only bound. For a future-like configuration with sensitivities comparable to the SKA and Theia/Gaia-NIR, the astrometric channels contribute significantly to the constraining power, and the joint limit improves to $m_g<0.48 \times 10^{-24} \, \mathrm{eV}/c^2$. These forecasts indicate that PTA -- astrometry multichannel inference provides a viable avenue for improving graviton-mass constraints under next-generation observational conditions. |
| title | Forecasting graviton-mass constraints from the full covariance of PTA-astrometry ORF estimators |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2604.23384 |