February 2025 - 45 articles
We study the Stueckelberg field in de Sitter space, which is a massive vector field with the gauge fixing (GF) term 12ζ(Aμ;μ)2. We obtain the vacuum stress tensor, which consists of the transverse, longitudinal, temporal, and GF parts, and...
Addressing the astronomical challenges posed by the interplay of data volume, AI sophistication, and energy consumption is crucial for the future of astronomy. As astronomical surveys continue to produce vast amounts of data, the computational and en...
Be stars are rapidly rotating B-type stars surrounded by circumstellar disks formed from self-ejected material. Understanding the mechanisms driving mass ejection and disk formation, known as the Be phenomenon, requires a detailed investigation of th...
On 25 February 2014 at around 00:39 UT, a major solar flare (code: SOL2014-02-25T00:39) erupted at sunspot region AR11990. Using the updated science quality data of GOES-15, it has been classified as an X7.13 solar flare. This gave rise to the electr...
This review provides an observational perspective on the fundamental properties of super-Eddington accretion onto supermassive black holes in quasars. It begins by outlining the selection criteria, particularly focusing on optical and UV broad-line i...
We present a comprehensive comparison of different Markov chain Monte Carlo (MCMC) sampling methods, evaluating their performance on both standard test problems and cosmological parameter estimation. Our analysis includes traditional Metropolis&ndash...
It is always more evident that the kinematics of galaxies provide us with unique information on the Nature of the dark particles and on the properties of the galaxy Dark Matter (DM) halos. However, in investigating this topic, we have to be very care...
Thermal relics with masses in the GeV to TeV range remain possible candidates for the Universe’s dark matter (DM). These neutral particles are often assumed to have vanishing electric and magnetic dipole moments so that they do not interact wit...
In the present work, we study cosmology in dilatonic f(R,T) gravity to address the inflationary phase of the early universe. As usual, in dilatonic gravity, the scalar potential assumes the exponential form. However, this potential is not good enough...
Based on Newtonian mechanics, in this article, we present a heuristic derivation of the Friedmann equations, providing an intuitive foundation for these fundamental relations in cosmology. Additionally, using the first law of thermodynamics and Euler...
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