Results from Hubble Parameter Data: Oscillating Dark Energy?

Abstract Using a model-independent analysis method which is based on the Lagrange mean value theorem for obtaining the derivative of the Hubble function, we analyze H ( z ) parameter data with some restrictive conditions. We find that: (a) the Universe may experience an accelerated expansion with a confidence level greater than 5 σ at redshift z 101 ∈ (0, 0.36) and greater than 1.9 σ at redshifts z 3835 ∈ (1.3, 1.53) and z 3836 ∈ (1.43, 1.53), where z j < z ij < z i and i marks the i th Hubble parameter data we consider; (b) the Universe may experience a decelerated expansion with a confidence level greater than 1.5 σ at redshift z 2012 ∈ (0.40, 0.52); (c) w x ≤ w t < −​​​​​​1 with confidence level greater than 1.6 σ at redshift z 3836 ∈ (1.43, 1.53). These results indicate that the evolution of dark energy may be oscillatory.