3 papers
astro-ph.HE2026
Potential periodic signals in blazars: significance, forecasting and deep learning
M. A. Hashad, A. Hammad, Amr A. EL-Zant
Blazars exhibit variable emission on diverse timescales. Some light curves show signs of quasiperiodic oscillations (QPOs), which may encode clues regarding the physical processes…
astro-ph.CO2025
Clustered unified dark sector cosmology: Background evolution and linear perturbations in light of observations
Mahmoud Hashim, Amr El-Zant
We consider unified dark sector models in which the fluid can collapse and cluster into halos, allowing for hierarchical structure formation to proceed as in standard cosmology. We…
astro-ph.HE2024
Quasi-periodic -ray modulations in the blazars PKS 2155-83 and PKS 2255-282
M. A. Hashad, Amr A. El-Zant, Y. Abdou +1
While there has been an increase in interest in the possibility of quasi-periodic oscillations (QPOs) in blazars, the search has hitherto been restricted to sources with well-sampl…