Linear Gas Dynamics in the Expanding Universe: Why the Jeans Scale does   not Matter
  We investigate the relationship between the dark matter and baryons in the linear regime. This relation is quantified by the so-called ``filtering scale''. We show that a simple gaussian ansatz which uses the filtering scale provides a good approximation to the exact solution. 
Nickolay Y. Gnedin, Emily J. Baker, Thomas J. Bethell, Meredith M.   Drosback, A. Gayler Harford, Amalia K. Hicks, Adam G. J...