  The thermal state of the fluid is governed by the ratio of the thermal and
the rest energy. This brings the composition of the fluid into the picture.
Although, fluid composed of lighter particles (e.g: electron-positron pair
plasma) at same temperature, is more relativistic compared to fluids with
finite baryon loading, but this is not necessarily true when baryon poor
transonic fluid are compared with each other. It can be shown that the
transonic pair-fluid is the least relativistic. This has far reaching
consequences on accreting flows around compact objects and are expected to have
similar effect on relativistic outflows and explosive events as well.
