Color characteristics of the blazar S5 0716+714 under geometrical origin of the long-term variability

The optical radiation of the blazar S5 0716+714 is formed within its ultrarelativistic jet in a compact region located near the true origin of the jet. Assuming that the variability is formed only by changing the relativistic radiation amplification coefficient (Doppler factor) for some part of the emitting region and that the spectrum of the emitting region, characterized by a power law at the observed frequencies, has a turn-over at lower frequencies, caused by synchrotron self-absorption, we analyze the archival data of the Crimean Astrophysical Observatory of B-, V-, R-, I-photometry of the blazar S5 0716+714 from 2002 to 2019. An explanation for the observed change in the color index during the blazar S5 0716+714 variability without changes in the physical parameters of the source was obtained.

Усиление терагерцового излучения высокодобротными резонансными плазмонами в двухслойной периодической структуре на основе графена в режиме антикроссинга плазмонных мод

The spectrum of amplification of terahertz radiation in a structured active graphene bilayer consisting of two identical periodic graphene microribbon arrays separated by a thin dielectric barrier layer is theoretically investigated. The system supports optical and acoustic plasmon modes. The resonant frequencies of the optical and acoustic modes change oppositely with the dielectric-layer thickness, which allows plasmon-mode anticrossing. It is shown that the investigated graphene structure is characterized by a strong plasmon response and giant terahertz-radiation amplification at plasma resonance frequencies in the vicinity of the anticrossing between the optical and acoustic plasmon modes at room temperature.