Strongly hopfian manifolds as codimension-2 fibrators

If a closed n-manifold N has a 2−1 covering, we consider the covering space Ñ of N corresponding to H, where H is the intersection of all subgroups Hi of index 2 in π1(N), i.e., H = ∩iϵI Hi with [π1(N) : Hi] = 2 for i ϵ I. We will show that if π1(N) is residually finite, χ(N) ≠ 0, and Ǹ is hopfian, then N is a codimension-2 fibrator. And then, we will also get several results about codimension-2 fibrators as its corollaries.