299 citations · 1.1k across the 42 of their papers we have counts for
45 papers
Sensitivity of calibration-free DESI DR2 BAO--supernova constraints to a distance-duality tilt
Stéphane Fay, Mikel Artola, Leandros Perivolaropoulos
Recent measurements from DESI baryon acoustic oscillations (BAO) have reported a moderate preference for dynamical dark energy, challenging the CDM paradigm. Nonetheless, such a…
The friction-era VOS amplitude of a string network from nematic disclination data
Dimitrios Efstratiou, Evangelos Achilleas Paraskevas, Leandros Perivolaropoulos
A tangle of line defects coarsens as the mean spacing between neighbouring lines grows. In a viscous medium the motion is overdamped, and the velocity-dependent one-scale (VOS)…
Cosmographic Reconstruction of the Quintessence Potential in Scalar-Tensor Gravity
G. Antonopoulos, L. Perivolaropoulos
We generalise the cosmographic reconstruction programme of Chakraborty, Dunsby & Scherrer to scalar-tensor gravity. Working in the Jordan frame with a general non-minimal coupling…
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…
On the origin of the BAOtr-DESI tension
Ioannis Pantos, Leandros Perivolaropoulos
The fiducial-independent angular/transverse BAO dataset, obtained from two-point angular correlation functions in thin redshift shells (hereafter BAOtr), systematically prefers sma…
Impact of the SNe Ia Magnitude Transition at 20 Mpc on Cosmological Parameter Estimation
Leandros Perivolaropoulos, Chrisostomos-Panagiotis Stamou
We investigate the impact of a late-time transition in the standardized absolute magnitude on the best-fit values of cosmological parameters using the Pantheon+ dataset. Extend…
Testing gravitational wave polarizations with LISA
Shingo Akama, Maxence Corman, Paola C. M. Delgado +16
In this paper we quantify the ability of the Laser Interferometer Space Antenna (LISA) to test the presence of non-tensorial polarizations as well as modifications to the tensor on…
Status of the Tension: A 2026 Review of Probe Discrepancies
Ioannis Pantos, Leandros Perivolaropoulos
The parameter quantifies the amplitude of matter density fluctuations. A persistent discrepancy exists between early-universe CMB observations and…
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…
Dissecting the Hubble tension: Insights from a diverse set of Sound Horizon-free H0 measurements
Ioannis Pantos, Leandros Perivolaropoulos
The Hubble tension is commonly framed as a discrepancy between local, late-time measurements favoring km s Mpc and early-time, Sound-Horizon-based me…
Addressing the DESI DR2 Phantom-Crossing Anomaly and Enhanced Tension with Reconstructed Scalar-Tensor Gravity
Dimitrios Efstratiou, Evangelos Achilleas Paraskevas, Leandros Perivolaropoulos
Recent cosmological data, including DESI DR2, highlight significant tensions within the CDM paradigm. When analyzed in the context of General Relativity (GR), the latest DESI da…
Large-scale peculiar velocities in the universe
Christos G. Tsagas, Leandros Perivolaropoulos, Kerkyra Asvesta
Observations have repeatedly confirmed the presence of large-scale peculiar motions in the universe, commonly referred to as ``bulk flows''. These are vast regions of the observabl…
BAO miscalibration cannot rescue late-time solutions to the Hubble tension
Davide Pedrotti, Luis A. Escamilla, Valerio Marra +2
Baryon Acoustic Oscillation (BAO) measurements play a key role in ruling out post-recombination solutions to the Hubble tension. However, because the data compression leading to th…
Hubble Tension and the G-step Model: Re-examination of Recent Constraints on Modified Local Physics
Leandros Perivolaropoulos, Ruchika
We critically examine recent claims challenging the viability of the G-step model (GSM) as a solution to the Hubble tension. The GSM proposes a 4 % increase in the effective…
Probing the Universe's Topology through a Quantum System?
Evangelos Achilleas Paraskevas, Leandros Perivolaropoulos
The global topology of the Universe could, in principle, affect quantum systems through boundary condition constraints. We investigate this connection by analyzing how compact, fla…
Dynamical dark energy with AdS-dS transitions vs. Baryon Acoustic Oscillations at 2.3-2.4
Özgür Akarsu, Maxim Eingorn, Leandros Perivolaropoulos +2
In this paper, written in memory of Alexei Starobinsky, we discuss the observational viability of the Ph-CDM model - a dynamical dark energy scenario based on a phantom…
Multi-Parameter Transitions in Cosmological Calibrators: A Resolution to the Hubble Tension from SH0ES Data Analysis
Mohit K. Sharma
The Hubble tension, characterized by discrepant measurements of the Hubble constant from early and late universe probes, remains one of the most significant challenges in cosmology…
The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
Eleonora Di Valentino, Jackson Levi Said, Adam Riess +533
The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades.…
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…
Dynamical dark energy with AdS-to-dS and dS-to-dS transitions: Implications for the tension
Özgür Akarsu, Leandros Perivolaropoulos, Anna Tsikoundoura +2
We investigate the dynamics and cosmological implications of dark energy (DE), modeled as a scalar field with a hyperbolic tangent potential that induces a smooth shift in the effe…
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…
Linear matter density perturbations in the CDM model: Examining growth dynamics and addressing the tension
Özgür Akarsu, Arman Çam, Evangelos A. Paraskevas +1
We investigate linear matter density perturbations in the CDM, in which the is replaced by late-time () mirror AdS-dS transition, resulting in distinct growt…
Hubble Tension or Distance Ladder Crisis?
Leandros Perivolaropoulos
We present an up-to-date compilation of published Hubble constant () measurements that are independent of the CMB sound horizon scale. This compilation is split in two distinc…
Effects of a local physics change on the SH0ES determination of
Ruchika, Leandros Perivolaropoulos, Alessandro Melchiorri
The Hubble tension, a significant discrepancy between the Hubble constant () values derived from early-time (Cosmic Microwave Background and Baryon Acoustic Oscillations) and…