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?
Thanks
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?
Thanks