Damghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260216Criticality in Nonconformal Plasmas at Finite Temperature and Density299310206610.22128/ijaa.2026.3168.1234ENLeila ShahkaramiSchool of Physics, Damghan University, Damghan 36716-45667, Iran.Journal Article20251128We study the thermodynamics of an asymptotically AdS black hole in a holographic Einstein-Maxwell-dilaton model describing a nonconformal plasma at finite temperature and chemical potential. Using a logarithmic warp factor and working in the grand canonical ensemble, we analyze the temperature-horizon relation, entropy density, grand potential, pressure, energy density, and trace anomaly, demonstrating the emergence of a first-order phase transition at low chemical potentials, a critical end point, and a smooth crossover at higher chemical potentials. Thermodynamic response functions, including the heat capacity and charge susceptibility, exhibit finite jumps at the first-order transition, divergence at the critical end point, and broad maxima in the crossover region. These results collectively establish a consistent and QCD-like phase structure in this holographic framework.https://ijaa.du.ac.ir/article_2066_303441c47ed9af1738894c23079e19a6.pdfDamghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260314Evolutionary Structure of Magnetized Accretion Flow Incorporating Saturated Thermal Conduction311322207610.22128/ijaa.2026.3224.1243ENKazem FagheiSchool of Physics, Damghan University, Damghan, IranMotahareh MohammadpourSchool of Physics, Damghan University, Damghan, Iran0000-0003-2941-8980Journal Article20260126This paper presents a time-dependent model for magnetized, advection-dominated accretion flows (ADAFs) that incorporates non-ideal effects, specifically resistivity and saturated thermal conduction. We apply a self-similar method to transform the full time-dependent magnetohydrodynamic (MHD) equations into a set of coupled ordinary differential equations, enabling us to investigate the evolving radial structure influenced by turbulent viscosity, magnetic diffusivity, and non-local energy transport. The resulting solutions confirm that the flow structure is inherently time-dependent. Numerical results demonstrate that increasing the efficiency of outward energy transport via saturated conduction weakens turbulence, reduces dissipation and temperature, increases density, and reduces the radial infall velocity while increasing the rotational velocity. In contrast, stronger magnetization leads to enhanced magnetic fields, lower temperatures, and faster radial inflow. We further show that the turbulence prescription parameter, which controls the pressure dependence of transport coefficients, significantly influences the balance between magnetic and thermal support. This framework offers a dynamic perspective on magnetized accretion flows, highlighting how non-ideal magnetic effects and conduction regulate the flow structure.https://ijaa.du.ac.ir/article_2076_a2dac6797bddfb77db28daa876007c0b.pdfDamghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260101Time-Series Forecasting of Geomagnetic Activity: A Data-Driven Approach for K_P Index Prediction323334210610.22128/ijaa.2026.3282.1245ENSevim RanjbarFaculty of Physics, University of Tabriz, PO Box 51666-16471, Tabriz, IranSomayeh TaranFaculty of Physics, University of Tabriz, PO Box 51666-16471, Tabriz, Iran0000-0001-7101-7449Journal Article20260225The geomagnetic index $\emph K_{\rm p}$ is a fundamental metric for quantifying geomagnetic activity and understanding solar-terrestrial physics. Accurately modeling and predicting its non-linear fluctuations remains a significant challenge in the study of space climate. In this research, we propose a robust statistical approach using a Long Short-Term Memory (LSTM) neural network for the time-series forecasting of the $\emph K_{\rm p}$ index. Our models are trained and evaluated on a comprehensive dataset spanning a 25-year period from 1999 to 2024, utilizing high-resolution solar wind data sourced from the NASA OMNIWeb database. We incorporate eight critical physical parameters as input features, including three-dimensional magnetic field components and plasma properties. A critical aspect of sequential modeling is determining the optimal historical context. Therefore, we systematically evaluate the impact of various input time windows (6, 12, 24, 48, 72, and 120 hours) on the predictive performance of the network. Our empirical analysis reveals that the 6-hour input window yields the highest precision, achieving an $R^2$ score of 0.7233 and minimizing the root mean square error (RMSE). These results indicate that short-term solar memory contains the most relevant dynamical features for forecasting geomagnetic variations. This study highlights the effectiveness of LSTM architectures in capturing the short-term dynamical evolution of the Earth's magnetic environment, offering valuable insights for future data-driven research in space physics.https://ijaa.du.ac.ir/article_2106_db843717858b34217e32c8f1e20697aa.pdfDamghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260715The Effect of Temperature Anisotropy on Ignition Conditions of Advanced Fuel Degenerate Plasma in the Presence of a Magnetic Field in Nuclear Fusion Configurations335346213510.22128/ijaa.2026.3311.1247ENMajid BakhtiyariDepartment of Physics, Faculty of Basic Sciences, University of Mazandaran, P.O. Box 47415-416, Babolsar, IranMohammad MahdaviDepartment of Physics, Faculty of Basic Sciences, University of Mazandaran, P.O. Box 47415-416, Babolsar, IranFatemeh Khodadadi AzadboniDepartment of Physics Education, Farhangian University, P.O. Box 14665-889, Tehran, IranJournal Article20260504The investigation of the impact of effective parameters on optimizing fuel pellet ignition conditions in nuclear fusion is one of the important topics in nuclear power generation cycles. ICF and MIF are two advanced methods for nuclear power generation. This paper investigates the influence of temperature anisotropy and external magnetic fields on the ignition conditions of advanced Deuterium-Helium-3 $(D-^3He)$ fuel pellets within degenerate plasma, specifically under Inertial Confinement Fusion (ICF) and Magneto-Inertial Fusion (MIF) regimes. Since the degeneration condition is fulfilled at low temperatures and high densities, it is expected that better ignition will be achieved by reducing the electron temperature. Calculations show that applying an external magnetic field to the $(D-^3He)$ fuel pellet plasma increases the surface density by a factor of five in the magnetized inertial fusion (MIF) state compared to the inertial confinement fusion (ICF) state, while maintaining the stability of the plasma degenerate conditions. This increase in the surface density of the fuel leads to an increase in the energy deposition of alpha particles into the plasma environment of the fuel pellet. In addition, it has been shown that by applying temperature anisotropy to the fuel pellet, the plasma electron temperature in the MIF mode is reduced by $ 70\% $, surpassing the reduction observed in ICF mode. The reduction in the electron temperature of the plasma environment, decreases the dissipated bremsstrahlung power, while simultaneously increasing the plasma temperature of the fuel pellet thereby facilitating more effective ignition of the $(D-^3He)$ fuel pellet.https://ijaa.du.ac.ir/article_2135_d17c1a35cf9de604a9645219e3e7c816.pdfDamghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260728Gravitational Lens Detection in Simulated LSST Data: A Comprehensive Feature Extraction Approach347357214010.22128/ijaa.2026.3309.1246ENSeyedeh Nahid HasaniDepartment of Physics, University of Guilan, 41335-1914, Rasht, IranNasibe AlipourDepartment of Physics, University of Guilan, 41335-1914, Rasht, Iran0000-0003-3643-5121Reza SaffariDepartment of Physics, University of Guilan, 41335-1914, Rasht, Iran0000-0002-7186-8371Journal Article20260430Identifying strong gravitational lensing systems is a major challenge in modern astronomical surveys. This research presents a machine learning-based method to distinguish lensed objects from non-lensed objects using multiband data.<br />To this end, a comprehensive set of physically interpretable features is extracted from simulated data across the g, r, i, and z bands. These features capture statistical, spatial, amplitude, and frequency information. Then, using the XGBoost algorithm, we identify the features that have the greatest impact on the classification process. The model used in this study primarily relies on indicators of structural complexity (such as spread, entropy, and kurtosis) and asymmetry (such as skewness), especially in the g band. Our analysis shows that the proposed model achieves strong performance, with an accuracy of 0.88 and a TSS score of 0.75. Additionally, the Area Under the Curve (AUC) of 0.94 demonstrates the model's high ability to distinguish between gravitational lenses and non-lensed systems. Overall, the proposed framework can provide a reliable approach for identifying gravitational lens candidates.https://ijaa.du.ac.ir/article_2140_0afd552686ebc3db5d6d4954792b7877.pdfDamghan University PressIranian Journal of Astronomy and Astrophysics2322-492412420260912Collisional Effects on Instabilities in Weakly Ionized Counterstreaming Plasmas359370216110.22128/ijaa.2026.3335.1249ENTaghi MirzayeDepartment of Physics Education, Farhangian University, P.O. Box 14665-889, Tehran, Iran0000-0002-1336-2639Mohammadreza TaghadosiDepartment of Physics, Salman Farsi University of Kazerun, Kazerun, Iran;
Institut f\"ur Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universit\"at Bochum, D-44780 Bochum, Germany0000-0002-3994-8224Journal Article20260530The growth and damping of instabilities in weakly ionized counterstreaming plasmas were investigated by using of the dispersion relation for electrostatic longitudinal waves. Initially, in the collisionless regime, the frequency spectrum and damping rate were calculated, revealing that energy dissipation is primarily governed by mechanisms such as Landau damping. Subsequently, by including electron–neutral and ion–neutral collision terms, the plasma response and consequently, the growth/damping rates of instabilities were modified. Collisions emerged as effective dissipation mechanisms. A comparison between the collisional and collisionless regimes indicates that the ion–neutral collision term and Landau damping contribute most significantly to instability damping, while the thermal effects of ions play a relatively weaker role in the damping rate. Furthermore, it was determined that an increase in the electron collision frequency reduces the damping rate and enhances instability growth.https://ijaa.du.ac.ir/article_2161_05524c148fbd138f81c5c9a10627fd4f.pdf