A universal property for the Jiang-Su algebra

Abstract

We prove that the infinite tensor power of a unital separable C*-algebra absorbs the Jiang-Su algebra Z tensorially if and only if it contains, unitally, a subhomogeneous algebra without characters. This yields a succinct universal property for Z in a category so large that there are no unital separable C*-algebras without characters known to lie outside it. This category moreover contains the vast majority of our stock-in-trade separable amenable C*-algebras, and is closed under passage to separable superalgebras and quotients, and hence to unital tensor products, unital direct limits, and crossed products by countable discrete groups. One consequence of our main result is that strongly self-absorbing ASH algebras are Z-stable, and therefore satisfy the hypotheses of a recent classification theorem of W. Winter. One concludes that Z is the only projectionless strongly self-absorbing ASH algebra, completing the classification of strongly self-absorbing ASH algebras.