Related papers: Radio Galaxies at VHE energies
We discuss ultra-high energy (UHE) cosmic rays (CR) from minor sources and their possible contribution to the extragalactic diffuse gamma-ray emission. As an illustration of minor sources we consider possible specific type of active…
Superluminal motion is a common feature of radio jets in powerful gamma-ray emitting active galactic nuclei. Conventionally, the variable emission is assumed to originate near the central supermassive black-hole where the jet is launched on…
New generational very-high-energy telescope arrays have been detecting more than 120 TeV {\gamma}-ray sources. Multi-wavelength observations on these Gamma-ray sources have proven to be robust in shedding light on their nature. The coming…
We investigate the properties and the environment of radio sources with optical counterpart from the combined VLA-COSMOS and zCOSMOS samples. The advantage of this sample is the availability of optical spectroscopic information, high…
Arrival directions of ultra-high energy cosmic rays from the direction of ten brightest radio sources lying within 50 Mpc from our Galaxy were studied by using recent models of the largescale Galactic magnetic field. A detailed study, where…
We explore non-thermal emission from a shocked interstellar medium, which is identified as an expanding shell, driven by a relativistic jet in active galactic nuclei (AGNs). In this work, we particularly focus on parsec-scale size…
We study the origin of the extragalactic diffuse gamma-ray background using the data from the Fermi telescope. To estimate the background level, we count photons at high Galactic latitudes |b|>60 degrees. Subtracting photons associated to…
High-redshift radio galaxies (HzRGs) are some of the rarest objects in the Universe. They are often found to be the most massive galaxies observed at any epoch and are known to harbour active supermassive black holes that give rise to…
We have mapped 16 edge-on galaxies at 20 cm using the VLA. For 5 galaxies, we could form spectral index, energy and magnetic field maps. We find that all but one galaxy show evidence for non-thermal high latitude radio continuum emission,…
The propagation of very high energy gamma-rays ($E>100$~GeV) over cosmological distances is suppressed by pair-production processes with the ubiquitous extra-galactic soft photon background, mainly in the optical to near infra-red. The…
The majority of nearby radio-loud AGN are found in massive, old elliptical galaxies with weak emission lines. At high redshifts,however, most known radio AGN have strong emission lines. In this paper, we examine a subset of radio AGN with…
Extended radio emission and its relation to parent galaxy properties is briefly reviewed. Our current understanding of the relation between absolute radio and optical luminosity, radio morphology and linear size is discussed. The impact of…
We present a detailed study of radio-detected dwarf galaxies (with stellar masses less than 3 billion solar masses) to characterize extreme star formation and search for (variable) radio AGNs. Our sample comes from Reines et al. (2020)…
Recent ground based and space telescopes that detect high energy photons from a few up to hundreds of gigaelectron volts (GeV) have opened a new window on the universe. However, because of the relatively poor angular resolution of these…
Studies of the inner few parsecs at the Galactic Centre provide evidence of a supermassive black hole, associated with the unusual, variable radio and infrared source Sgr A*. Our major aim is the study and analysis of the physical processes…
The central nuclei of galaxies, where super-massive black holes (SMBHs) are thought to reside, can experience phases of activity when they become Active Galactic Nuclei (AGN). An AGN can eject winds, jets, and produce radiation across the…
A few FRI radio galaxies were detected at GeV gamma-rays with CGRO EGRET, with peroperties suggesting that the gamma-ray flux originates from the core. Here we discuss the possibility that the extended radio features of radio galaxies could…
Radio galaxies are intensively discussed as the sources of cosmic rays observed above about $3\,{\times}\,10^{18}\,\text{eV}$, called ultra-high energy cosmic rays (UHECRs). We present a first, systematic approach that takes the individual…
Various types of active galactic nuclei (AGN) are briefly discussed, with an emphasis on the theory of recent X-ray and $\gamma$-ray observations of the subclass, Seyfert 1 galaxies. The large radiation power from AGN is thought to…
Despite the plethora of deep (sub-mJy) radio surveys there remains considerable doubt as to the exact nature of the galaxies contributing to the source counts. Current evidence suggests that starformation in moderately luminous 'normal'…