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The Cauchy problem in $\mathbb R^n$ is considered for \begin{eqnarray*}\left\{ \begin{array}{l}  u_t = \Delta u - \nabla \cdot (u\nabla v),\\ 0 = \Delta v + u. \end{array}\right. \end{eqnarray*} For each $n\ge 10$, a statement on stability andattractiveness of the singular steady state given by \[u_\star(x):=\frac{2(n-2)}{|x|^2},\qquad x\in\mathbb R^n\setminus\{0\}, \] isderived within classes of nonnegative radial solutions emanating from initialdata less concentrated than $u_\star$. In particular, for any such $n$ it isshown that infinite-time blow-up occurs for all radial initial data which areless concentrated than $u_\star$ and satisfy \[ u_0(x) \ge \frac{2(n-2)}{|x|^2}- \frac{C}{|x|^{2+\theta}}\qquad \mbox{for all } x\in \mathbb R^n\setminusB_1(0) \] with some $C>0$ and some $\theta>\frac{n-2+\sqrt{(n-2)(n-10)}}{2}$.  This is complemented by a result which, in the case when $3\le n \le 9$,asserts instability of $u_\star$ as well as the existence of a boundedabsorbing set for all radial trajectories initially less concentrated than$u_\star$.  In particular, previous knowledge on stability properties of $u_\star$, ashaving been gained for $n\ge 11$ in [24], is thereby extended to any dimension$n\ge 3$.

Stability vs. instability of singular steady states in the parabolic-elliptic Keller-Segel system on $\mathbb R^n$