Dark energy, dark matter and the Chaplygin gas
  The possibility that the dark energy may be described by the Chaplygin gas is discussed. Some observational constraints are established. These observational constraints indicate that a unified model for dark energy and dark matter through the employement of the Chaplygin gas is favored. 
R. Colistete Jr., J. C. Fabris, S. V. B. Goncalves and P. E. de Souza