On an
-dimensional
complete manifold
,
consider an
-almost
gradient Ricci soliton, which is a generalization of a gradient
Ricci soliton. We prove that if the manifold is Bach-flat and
, then the
manifold
is either
Einstein or rigid. In particular, such a manifold has harmonic Weyl curvature. Moreover, if the
dimension of
is
four, the metric
is locally conformally flat.
Keywords
$h$-almost gradient Ricci soliton, Bach-flat, Einstein
metric