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Alternative equation of state?

  1. Mar 8, 2009 #1
    I'm aware that the equation of state for a perfect fluid (when considering single fluid cosmology) is p=w*rho

    However I've come across an equation of state of p=w*rho - xi*H, H being Hubble's parameter. However I cannot find an explanation of why you can put this in? Can anyone explain this to me please?

  2. jcsd
  3. Mar 9, 2009 #2


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    It is irrelevant. You wish to inject it into the cosmological constant?
  4. Mar 9, 2009 #3
    its to look at equations for rhodot (d rho/dt) and Hdot (dH/dt) so solve as a dynamical system for rho and H
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