Stellar-mass black hole binaries represent critical environments for exploring the complex coupling between relativistic gravity, angular momentum transport, and high-energy radiation. This work investigates how black hole spin and orbital separation modulate mass transfer efficiency, jet energetics, and emission behaviour in such systems. To this end, we employ a hybrid framework combining analytical models with two-dimensional general relativistic magnetohydrodynamics (GRMHD) simulations, focusing on variations in gravitational potential, inflow rate, and spectral structure across a range of black hole masses (M) and spin values (a). We introduce a novel empirical formulation for the mass transfer rate, M(r,M͙, a), which captures non-linear spin-radius coupling and enables accurate modelling of disk-jet interaction. Our simulations reveal that a critical spin threshold around a ≈ 0.7 leads to a steep rise in jet power, in alignment with Blandford–Znajek predictions. Furthermore, relativistically redshifted emission spectra derived from disk regions show strong agreement with observed X-ray data from Cygnus X-1 and V404 Cygni. These results establish a predictive link between system configuration and observable features, offering a robust foundation for interpreting spectral and timing behaviour in accreting black hole binaries.
Attempts to understand the mechanisms driving galaxy and their structures formation contributed to the formulation of various theoretical models describing this issue. Various scenarios make different predictions regarding the orientation of galaxies within large-scale structures, the distribution of their spins directions, and the alignment between the brightest galaxy in the cluster and the major axis of the structure. For this reason, the study of galaxy orientation provides a observational tool for testing models of their formation and remains a cornerstone of extragalactic astronomy and cosmology. The proper study requires consideration of the fact that galaxies are oblate spheroids with the real axis ratios dependent on the morphological type. However, most of the astronomical data available today lacks this type of information. As a result, a new method of investigation based on the estimated frequency of the occurrence of given morphological types of galaxies may prove to be an alternative. The method was applied to galaxies belonging to the clusters of the Local Supercluster using data from Sloan Digital Sky Survey. The obtained results confirm the theoretically predicted lack of significant alignment of the studied galaxies.
In this paper, we present a comprehensive analysis and validation of four exoplanet candidates, TOI-1001.01, TOI-1007.01, TOI-1019.01 and TOI-1032.01 selected from the NASA Exoplanet Archive. We use data from Transiting Exoplanet Survey Satellite (TESS) and apply the transit method to identify periodic dimming events, which are indicative of planetary transits. To obtain the best-fit and de-trended fluxes for our objects we used the the box-least squares (BLS) models. In addition, we performed odd-even transit and background-flux analysis for the further validation of candidates as true exoplanets.
In this work, we analyzed the orbits of over 35000 (as of 2024) near-Earth objects (NEOs) focusing on the potential for successive approaches to all pairs of planets: Earth, Venus, and Mars during the period from 2020 to 2120. We selected 120 candidates for fast transfers (within 180 days) between the following planet pairs: Earth-Mars, Earth-Venus, Mars-Earth, Mars-Venus, Venus-Earth, and Venus-Mars. We found only two candidates for double transfers (consecutive approaches involving three planets), and 10 candidates for multiple transfers, where an asteroid exhibits several consecutive paired approaches to planets within a century.
In this study, we present the detailed study of the geomagnetic storm that occurred 6-10 October 2015. In literature this storm was classified as a two-step storm due to the observation of two large decreases of the disturbance storm time (Dst) index during the main storm phase. In addition, the strong thermal emission velocity enhancement (STEVE) event occurred during the same storm phase was photographically documented by citizen scientists at Minnesota Nevis (USA). The storm of 7 October 2015, which exhibits high-intensity, long-duration, continuous AE activity (HILDCAA), is one of the strongest storms of the recent 24th solar cycle. We examined changes in Dst index, interplanetary magnetic field (IMF) Bz, flow velocity, proton density, solar wind pressure, epsilon parameters and presented the discussion of the physical mechanism happened during this geomagnetic storm. The results obtained for the storm on 7 October 2015 were also compared with geomagnetic storms occurred on 8 March 2008, 25 July 2016 and 8 September 2017.
