Correspondence between $f(G)$ Gravity and Holographic Dark Energy via   Power-law Solution
  In this paper, we discuss cosmological application of holographic Dark Energy (HDE) in the framework of $f(G)$ modified gravity. For this purpose, we construct $f(G)$ model with the inclusion of HDE and a well-known power law form of the scale factor $a(t)$. The reconstructed $f(G)$ is found to satisfy a sufficient condition for a realistic modified gravity model. We find quintessence behavior of effective equation of state (EoS) parameter $\omega_{DE}$ through energy conditions in this context. Also, we observe that the squared speed of sound $v_s^2$ remains negative which shows the instability of HDE $f(G)$ model. 
Abdul Jawad, Antonio Pasqua and Surajit Chattopadhyay
physics.gen-ph