Precision holography for N= 2 ^∗ on S ⁴ from type IIB supergravity

We find a new supersymmetric solution of type IIB supergravity which is holographically dual to the planar limit of the four-dimensional N= 2 ^∗ supersymmetric Yang-Mills theory on S⁴. We study a probe fundamental string in this background which is dual to a supersymmetric Wilson loop in the N= 2 ^∗ theory. Using holography we calculate the expectation value of this line operator to leading order in the ’t Hooft coupling. The result is a non-trivial function of the mass parameter of the N= 2 ^∗ theory that precisely matches the result from supersymmetric localization.