English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We study the effects of the null energy condition on totally umbilichypersurfaces in a class of static spacetimes, both in the spacelike and thetimelike case, respectively. In the spacelike case, we study totally umbilicwarped product graphs and give a full characterization of embedded surfaceswith constant spacetime mean curvature using an Alexandrov Theorem by Brendleand Borghini--Fogagnolo--Pinamonti. In the timelike case, we achieve acharacterization of photon surfaces with constant umbilicity factor similar toa result by Cederbaum--Galloway.

On effects of the null energy condition on totally umbilic hypersurfaces in a class of static spacetimes