299 citations · 1.1k across the 42 of their papers we have counts for
6 papers · 1 filter
A Friendly Phantom: Late-time AdS-to-dS transition and cosmological tensions
Özgür Akarsu, Leandros Perivolaropoulos, A. Emrah Yükselci +1
We present Ph-CDM, a phantom-scalar realization within General Relativity of the sign-switching cosmological-constant idea, CDM, in which a phantom scalar evo…
Static Dark Fluid Thin Shells in Schwarzschild-de Sitter Spacetimes: Stability and Black Hole Shadows
Dimitrios Efstratiou, Evangelos Achilleas Paraskevas, Leandros Perivolaropoulos
We study the existence and radial stability of static, spherically symmetric thin shells joining two Schwarzschild-de Sitter (SdS) spacetimes . Near the equilibrium…
Metastable Cosmological Constant and Gravitational Bubbles: Ultra-Late-Time Transitions in Modified Gravity
Dimitrios Efstratiou, Leandros Perivolaropoulos
The observed cosmological constant may originate as the minimum value of a scalar field potential, where the scalar field is frozen due to a large mass. If this vacuum is…
Gravitational Wave Signatures Induced by Dark Fluid Accretion in Binary Systems
Evangelos Achilleas Paraskevas, Leandros Perivolaropoulos
We investigate the impact of dark fluid accretion on gravitational waveforms emitted by a compact binary system consisting of a supermassive black hole and a stellar-mass black hol…
Special Issue on Modified Gravity Approaches to the Tensions of CDM: Goals and Highlights
Eleonora Di Valentino, Leandros Perivolaropoulos, Jackson Levi Said
The Special Issue on "Modified Gravity Approaches to the Tensions of CDM"} in the Universe journal tackles significant challenges faced by the CDM model, including discrepanc…
Spinning particle orbits around a black hole in an expanding background
I. Antoniou, D. Papadopoulos, L. Perivolaropoulos
We investigate analytically and numerically the orbits of spinning particles around black holes in the post Newtonian limit and in the presence of cosmic expansion. We show that or…