J-PAS and PFS surveys in the era of dark energy and neutrino mass measurements

TL;DR

The paper forecasts how joint J-PAS and PFS galaxy surveys, together with Stage-IV CMB measurements from the Simons Observatory and LiteBIRD, can tightly constrain $\sum m_ν$ and the dark-energy equation of state. Using Fisher matrices for both single- and multi-tracer galaxy analyses across a broad redshift range, the authors show that redshift complementarity and cross-tracer synergy significantly reduce parameter degeneracies. In the $Λ$CDM+$\sum m_ν+N_{eff}$ model, the combined data achieve $σ(\sum m_ν)=0.017$ eV, capable of disfavouring the inverted hierarchy at 2.34$\sigma$ if the true mass sum equals the normal-ordering minimum; for a time-varying $w(a)$, the joint data yield $σ(w_0)=0.044$ and $σ(w_a)=0.18$, corresponding to a 5.1$\sigma$ preference for dynamics. Overall, the study demonstrates that J-PAS and PFS will provide competitive, complementary tests of neutrino physics and cosmic acceleration when paired with Stage-IV CMB data.

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 CMB measurements from the Simons Observatory (SO) and \textsc{LiteBird} yields an expected precision of $σ(\sum m_ν)=0.017\,$eV in the $Λ$CDM$+\sum m_ν+N_{\rm eff}$ framework, sufficient to disfavour 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 $w_0w_a$CDM$+\sum m_ν+N_{\rm eff}$ 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.

Figures (11)

• Figure 1: Top: Linear cold-plus-baryonic matter power spectrum at $z=0$ for varying $\sum m_\nu$, normalized to the massless case. Middle: Power spectrum for $\sum m_\nu = 0.06$ eV relative to $\sum m_\nu = 0$ at different redshifts. Bottom: Linear growth rate of CDM+baryons at $z=1$ normalized to the massless case.
• Figure 2: Volume number density of targets in redshift bins. Top: J-PAS (shaded) and PFS (solid line). Bottom: DESI BGS, ELG, LRG, and QSO (shaded).
• Figure 3: Upper: Fractional uncertainties on cosmological parameters for different data combinations in the $\Lambda$CDM$+\sum m_\nu$ (shaded) and $\Lambda$CDM$+\sum m_\nu+N_\mathrm{eff}$ (hatched) models; Lower: same as the upper figure but for the $w_0w_a$CDM$+\sum m_\nu+N_\mathrm{eff}$ model. For the parameters $w_0$ and $w_a$, the uncertainties $\sigma_{\theta}$ are presented.
• Figure 4: Marginalized 68% and 95% confidence contours for the $\Lambda$CDM$+\sum m_\nu+N_\mathrm{eff}$ model using J-PAS ELG only (red) and the combination of three tracers (green).
• Figure 5: Same as Figure \ref{['lcdm_j-pas']}, but for the $w_0w_a$CDM$+\sum m_\nu+N_\mathrm{eff}$ model.