Abstract Fisher-matrix forecasts are presented for the cosmological surveys of the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS) and the Subaru Prime Focus Spectrograph (PFS). The wide, low-redshift coverage of J-PAS and the high-density, high-redshift mapping of PFS are strongly complementary: combining the two reduces marginalized uncertainties on all primary parameters compared with either survey individually. Adding the joint J-PAS+PFS data to next-generation cosmic microwave background (CMB) measurements from the Simons Observatory and LiteBIRD yields an expected precision of σ (∑ m ν ) = 0.017 eV in the ΛCDM+∑ m ν + N eff framework, sufficient to disfavor the inverted neutrino hierarchy at 2.34 σ if the true mass sum equals the normal-ordering minimum. Motivated by recent DESI results, we also forecast within a w 0 w a CDM+∑ m ν + N eff cosmology, adopting the DESI DR2 best-fit values ( w 0 = −0.758, w a = −0.82) as fiducial. The combination CMB+J-PAS+PFS then delivers σ ( w 0 ) = 0.044 and σ ( w a ) = 0.18, corresponding to a 5.1 σ preference for a time-varying dark-energy equation of state. These findings show that J-PAS and PFS, especially when coupled with Stage IV CMB observations, will provide competitive tests of neutrino physics and the dynamics of cosmic acceleration.
Qin et al. (Tue,) studied this question.