ScholarWorks@성균관대학교

초록

Accurate measurements of fundamental cosmological parameters, especially the Hubble constant (H0) and present-day matter density (Omega m0), are crucial for constraining dark energy (DE) evolution. We analyze the sensitivities of cosmological observables (H(z), DL(z), EG) to Omega m0, omega 0, and omega a under different parametrizations. Our results show observables are far more sensitive to Omega m0 than to DE equation of state parameters (e.g., at z similar to 0.5, H(z)'s Omega m0 sensitivity is similar to 0.7 vs. omega a's similar to 0.04). This hierarchy mandates high-precision Omega m0 measurements to accurately constrain time-varying DE. We also find DE parameter sensitivity highly depends on parametrization; the standard CPL form shows low sensitivity to omega a, but omega(z)=omega 0+omega aln(1+z) significantly enhances it. Our analysis of DESI DR1/DR2 data confirms these theoretical limits: standalone DESI data primarily provides only upper limits for omega a, underscoring insufficient constraining power for a definitive time-varying DE detection. While combined datasets offer tighter constraints, interpretation requires caution due to parametrization influence. We further confirm this point using simulated Supernovae MCMC data. In conclusion, improving Omega m0 precision and adopting optimized parametrizations are imperative for future surveys like DESI to fully probe dark energy's nature.

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