Universe, Volume 11, Issue 12

Building upon a thermodynamic formalism, we show that one-dimensional self-gravitating systems in hydrostatic equilibrium with a uniform density are in maximal entropy states when submitted to adiabatic perturbations, i.e., perturbations that maintai...

The adventure of the journal Universe began about ten years ago, when I received an invitation from Dr [...]

We review some aspects of accretion disks physics, spacetime photon shell and photon orbits, related to retrograde (counter-rotating) motion in Kerr black hole (BH) spacetimes. In this brief review, we examine the counter-rotating components of the K...

We present a comprehensive sensitivity study of future CEνNS detectors, focusing on a cryogenic cesium iodide detector and a tonne-scale liquid argon one, currently being developed by the COHERENT Collaboration. These setups will enable precision...

Measuring supermassive black hole (SMBH) masses is fundamental to understanding active galactic nuclei (AGN) and their coevolution with host galaxies. Among existing techniques, H2O megamaser observations with Very Long Baseline Interferometry (VLBI)...

This review examines the role of differential forms, Pfaffian systems, and hypersurfaces in general relativity. These mathematical constructions provide the essential tools for general relativity, in which the curvature of spacetime—described b...

We study basis-independent structures in the Type-I seesaw mechanism for light Majorana neutrinos, assuming the canonical scenario with three heavy right-handed (sterile) neutrinos. Let mν denote the 3×3 mass matrix of light neutrinos, obtai...

This review investigates the application of unsupervised machine learning algorithms to astronomical data. Unsupervised machine learning enables researchers to analyze large, high-dimensional, and unlabeled datasets and is sometimes considered more h...

Dark matter constitutes the predominant component of the universe, yet its fundamental nature remains elusive, motivating diverse physical and astrophysical investigations. Recently, gravitational waves have emerged as a new probe for detecting the d...

Axion warm inflation is studied within the framework of Logamediate inflation. Using a novel approach, we constrain the parameter space of the model and find a reasonable region of free parameters compatible with the temperature, polarization, and le...