Commun. Korean Math. Soc. 2020; 35(2): 639-651
Online first article March 17, 2020 Printed April 30, 2020
https://doi.org/10.4134/CKMS.c190247
Copyright © The Korean Mathematical Society.
Huchchappa Aruna Kumara, Venkatesha Venkatesha
Shankaraghatta; Shankaraghatta
Consider a gradient Einstein-type metric in the setting of $K$-contact manifolds and $(\kappa,\mu)$-contact manifolds. First, it is proved that, if a complete $K$-contact manifold admits a gradient Einstein-type metric, then $M$ is compact, Einstein, Sasakian and isometric to the unit sphere $\mathbb{S}^{2n+1}$. Next, it is proved that, if a non-Sasakian $(\kappa,\mu)$-contact manifolds admits a gradient Einstein-type metric, then it is flat in dimension $3$, and for higher dimension, $M$ is locally isometric to the product of a Euclidean space $\mathbb{E}^{n+1}$ and a sphere $\mathbb{S}^n(4)$ of constant curvature $+4$.
Keywords: Einstein-type manifolds, $K$-contact manifolds, Sasakian manifold, $(\kappa,\mu)$-contact manifold, Einstein manifold
MSC numbers: 53C25, 53C20, 53D15
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