Global Small Solutions of Heat Conductive Compressible Navier-Stokes Equations with Vacuum: Smallness on Scaling Invariant Quantity

In this paper, we consider the Cauchy problem to the heat conductive compressible Navier-Stokes equations in the presence a of vacuum and with a vacuum far field. Global well-posedness of strong solutions is established under the assumption, among some other regularity and compatibility conditions: that the scaling invariant quantity parallel to rho(0)parallel to infinity (parallel to rho(0)parallel to(3) + parallel to rho(0)parallel to(2)(infinity) parallel to root rho(0)mu(0)parallel to 22) (parallel to del mu(0)parallel to 22 + parallel to rho(0)parallel to infinity parallel to root rho E-0(0)parallel to 22) sufficiently small, with the smallness depending only on the parameters R, gamma, mu, lambda, and kappa in the system. Notably, the smallness assumption is imposed on the above scaling invariant quantity exclusively, and it is independent of any norms of the initial data, which is different from the existing papers. The total mass can be either finite or infinite. An equation for the density-more precisely for its cubic, derived from combining the continuity and momentum equations-is employed to get the L-t(infinity) (L-3) type estimate of the density.