Conformally K\"ahler geometry and quasi-Einstein metrics

Abstract

We prove that the quasi-Einstein metrics found by L\"u, Page and Pope on $\mathbb{C}P^{1}$-bundles over Fano K\"ahler-Einstein bases are conformally K\"ahler and that the K\"ahler class of the conformal metric is a multiple of the first Chern class. A detailed study of the lowest-dimensional example of such metrics on $\mathbb{C}P^{2}\sharp \overline{\mathbb{C}P}^{2}$ using the methods developed by Abreu and Guillemin for studying toric K\"ahler metrics is given. Our methods yield, in a unified framework, proofs of the existence of the Page, Koiso-Cao and L\"u-Page-Pope metrics on $\mathbb{C}P^{2}\sharp \overline{\mathbb{C}P}^{2}$. Finally, we investigate the properties that similar quasi-Einstein metrics would have if they also exist on the toric surface $\mathbb{C}P^{2}\sharp 2 \overline{\mathbb{C}P}^{2}$.