Mohammad Nazrul Islam Khan — Neckpinchhttps://neckpinch.com/authors/mohammad-nazrul-islam-khan/New arXiv papers by Mohammad Nazrul Islam Khan, from Neckpinch Tue, 03 Nov 2026 08:41:12 GMT Characterizations of generalized Robertson-Walker spacetimes concerning gradient solitonshttps://neckpinch.com/papers/2402.15339/arxiv:2402.15339Fri, 23 Feb 2024 00:00:00 GMTKrishnendu De, Mohammad Nazrul Islam Khan, Uday Chand De — In this article, we examine gradient type Ricci solitons and (m,τ)-quasi Einstein solitons in generalized Robertson-Walker (GRW) spacetimes. Besides, we demonstrate that in this scenario the GRW spacetime presents the Robertson-Walker (RW) spacetime and the perfect fluid (PF) spacetime presents the phantom era. Consequently, we show that if a GRW spacetime permits a gradient τ- Einstein solitons, then it also represents a PF spacetime under certain condition.Ricci solitonsAlmost & η-Ricci solitons