Observational tests of a two parameter power-law class modified gravity in Palatini formalism

摘要: CONTEXT: In this work we propose a modified gravity action $f(R)=({R}^{n}\ensuremath{-}{R}_{0}^{n}{)}^{1/n}$ with two free parameters of $n$ and ${R}_{0}$ derive the dynamics universe for in Palatini formalism. AIM: We do cosmological comparison model observed data to find best flat universe. METHOD: To constrain use SNIa type Ia sets gold union samples, CMB-shift parameter, baryon acoustic oscillation, gas mass fraction cluster galaxies, large-scale structure data. RESULT: The fit from observational results range $n={0.98}_{\ensuremath{-}0.08}^{+0.08}$ ${\ensuremath{\Omega}}_{M}={0.25}_{+0.1}^{\ensuremath{-}0.1}$ one sigma level confidence where standard $\ensuremath{\Lambda}\mathrm{CDM}$ resides solution.