Effective Matter Cosmologies of Massive Gravity: Physical Fluids
  We derive new cosmological solutions of the ghost-free massive gravity with a general background metric in which the contribution of the mass sector to the metric one is modeled by an effective cosmological constant and an ideal fluid which obeys the first law of thermodynamics; thus it satisfies the ordinary energy-momentum conservation or continuity equation. 
Nejat Tevfik Yilmaz
hep-th