We offer a pedagogical introduction to axion-like particles (ALPs) as far as their relevance
for high-energy astrophysics is concerned, from a few MeV to 1000 TeV. This review is self …

Supermassive black holes lying in the center of galaxies can launch relativistic jets of
plasma along their polar axis. The physics of black-hole jets is a very active research topic in …

We describe new implementations of leptonic and hadronic models for the broadband
emission from relativistic jets in active galactic nuclei in a temporary steady state. For the …

We calculate the spectral energy distribution (SED) of electromagnetic radiation and the
spectrum of high-energy neutrinos from BL Lac objects in the context of the synchrotron …

The jets of powerful blazars propagate within relatively dense regions of radiation produced
externally to the jet. This radiation is a key ingredient to understand the origin of the high …

We present results from monitoring the multi-waveband flux, linear polarization, and parsec-
scale structure of the quasar PKS 1510− 089, concentrating on eight major γ-ray flares that …

We have examined the compact structure in 250 flat-spectrum extragalactic radio sources
using interferometric fringe visibilities obtained with the Very Long Baseline Array (VLBA) at …

Blazars are the most violent steady/recurrent sources of high-energy gamma-ray emission in
the known Universe. They are prominent emitters of electromagnetic radiation throughout …

We introduce a methodology for analysis of multiwavelength data from X-ray-selected BL
Lac (XBL) objects detected in the TeV regime. By assuming that the radio-through-X-ray flux …

Powerful flares from blazars with short (∼ min) variability time-scales are challenging for
current models of blazar emission. Here, we present a physically motivated ab initio model …