32 citations · 55 across the 2 of their papers we have counts for
5 papers
Polytropic dark matter flows illuminate dark energy and accelerated expansion
K. Kleidis, N. K. Spyrou
Currently, a large amount of data implies that the matter constituents of the cosmological dark sector might be collisional. An attractive feature of such a possibility is that, it…
A conventional approach to the dark-energy concept
Kostas Kleidis, Nicholas K. Spyrou
Motivated by results implying that the constituents of dark matter (DM) might be collisional, we consider a cosmological (toy-) model, in which the DM itself possesses some sort of…
Covariant approach to the conformal dynamical equivalence in astrophysics
N. K. Spyrou, C. G. Tsagas
We use covariant techniques to examine the implications of the dynamical equivalence between geodesic motions and adiabatic hydrodynamic flows. Assuming that the metrics of a geode…
Spin-down of Relativistic Stars with Phase Transitions and PSR J0537-6910
N. K. Spyrou, N. Stergioulas
Using a highly accurate numerical code, we study the spin down of rotating relativistic stars, undergoing a quark deconfinement phase transition. Such phase transitions have been s…
Geodesic motions versus hydrodynamic flows in a gravitating perfect fluid: Dynamical equivalence and consequences
K. Kleidis, N. K. Spyrou
Stimulated by the methods applied for the observational determination of masses in the central regions of the AGNs, we examine the conditions under which, in the interior of a grav…