Interior spacetimes sourced by stationary differentially rotating irrotational cylindrical fluids. Perfect fluids

Abstract: In a recent series of papers new exact analytical solutions of the Einstein equations representing interior spacetimes sourced by stationary rigidly rotating cylinders of different kinds of fluids have been displayed, [Phys. Rev. D {\bf 104}, 064040 (2021); J. Math. Phys. {\bf 64}, 022501 (2023); J. Math. Phys. {\bf 64}, 032501 (2023); J. Math. Phys. {\bf 64}, 042501 (2023); and J. Math. Phys. {\bf 64}, 052502 (2023)]. This work is currently being extended to the cases of differentially rotating irrotational fluids. The results are presented in a new series of papers considering in turn the same three anisotropic pressure cases, as well as a perfect fluid source. Here, the perfect fluid case is considered, and different classes are identified as directly issuing from the field equations. Among them, an explicit analytical set of solutions is selected as displaying perfect fluid spacetimes. Its mathematical and physical properties are analyzed. Its matching to an exterior Lewis-Weyl vacuum and the conditions for avoiding an angular deficit are discussed.