Conveners
AGN III
- Andrew Chen (University of the Witwatersrand)
Presentation materials
Hydra A is a type I Fanaroff-Riley radio galaxy that hosts a pair of 300-kiloparsec diameter radio lobes that are being powered by one of the most of the powerful AGN outbursts known to date. Radio observations provide us with an excellent probe for the study of high-energy particles residing in the lobes. The MeerKAT radio telescope carried out observations of Hydra A, from which we obtained...
Extragalactic radio sources selected for geodetic and astrometric VLBI observations are expected to have a core-dominated point-like structure. However, it is a well-known fact that extragalactic radio sources often exhibit time- and frequency-dependent intrinsic source structure at milliarcsecond (mas) scale, making them subjects of routine monitoring. In this talk, I will present mas...
1ES 1959+650 is a well known HBL with its synchrotron peak lying in soft X-ray band (0.3-10.0keV). It is also observed that the peak position of synchrotron component changes significantly with the brightness state of this blazar. This source underwent first major TeV activity in 2015 after a long silence in VHE bands. We have compiled all the multi-wavelength data between 2015 to 2021...
The nuclei of galaxies show episodes of activity and of quiescence. Through feedback mechanisms, such episodes have significant effects on their surroundings. Radio observations can be excellent probes of such episodes, measuring time-integrated influence of the AGN jet activity. Sensitive radio observations can record faint emission associated with the previous epochs of activity, and it is...
Previous work on time-dependent shock-acceleration and radiation transfer in relativistic jets has successfully reproduced many spectral variability features of blazars if flaring activity is mediated by increasingly efficient diffusive shock acceleration. However, flaring events exhibiting a significant increase of the Compton dominance, or even "orphan" gamma-ray flares, are very difficult...
Blazars – active galaxies with the jet pointing at Earth – emit across all electromagnetic wavelengths. The so-called one-zone model has described well both quiescent and flaring states, however it cannot explain the radio emission. In order to self-consistently describe the entire electromagnetic spectrum, extended jet models are necessary. Notably, kinetic descriptions of extended jets can...
Blazars emit powerful electromagnetic (EM) radiation across all wavelengths. The broadband spectral energy distributions (SEDs) of EM emissions from these objects are characterised by two humps. The low frequency hump ranging from radio to infrared/X-ray emission is accepted as synchrotron radiation by primary leptons. The high frequency hump from X-rays to gamma-rays is attributed to...
The supermassive black holes in the centers of some active galaxies (AGN) eject powerful relativistic jets which propagate over kpc scales, showing no significant momentum loss. Both observational evidence as well as theoretical considerations from MHD simulations of jets suggests that they are radially stratified, with a fast inner spine surrounded by a slower-moving outer sheath. The...
