Towards celestial chiral algebras of self-dual black holes

In this note, we show that several self-dual spacetimes previously studied in the context of celestial and twisted holography arise as limits of a certain Taub-NUT AdS$_4$ metric, the Pedersen metric, in which their Mass, NUT charge and cosmological constant obey a self-duality relation. In particular, self-dual Taub-NUT, a singular double cover of Eguchi-Hanson space, Euclidean AdS$_4$, and non-compact $\mathbb{CP}^2$, which is conformally equivalent to Burns space, arise as special limits of the Pedersen metric. The Pedersen metric can be derived from a curved twistor space which we conjecture to arise from a backreaction of self-dual gravity in the presence of a cosmological constant when coupled to a defect operator wrapping a certain $\mathbb{CP}^1$ at infinity. The curved twistor space gives rise to a $2$-parameter deformation of the celestial symmetry algebra $Lw_\wedge$ which reduces to previously studied algebras in various limits.