Mode stability of self-similar wave maps without symmetry in higher dimensions

We consider wave maps from ( 1 + d ) (1+d) -dimensional Minkowski space into the d d -sphere. For every d ≥ 3 d ≥ 3 , there exists an explicit self-similar solution that exhibits finite time blowup. This solution is corotational and its mode stability in the class of corotational functions is known. Recently, Weissenbacher, Koch, and the first author proved mode stability without symmetry assumptions in d = 3 d =3 . In this paper we extend this result to all d ≥ 4 d ≥ 4 . On a technical level, this is the first successful implementation of the quasi-solution method where two additional parameters are present.