Conveners
Relativistic outflows from extragalactic sources
- Luigi Costamante
Relativistic outflows from extragalactic sources
- Markus Böttcher (NWU Potchefstroom)
We compare the energy requirements of different scenarios that allow addressing ultrafast gamma-ray variability recently reported by the MAGIC collaboration from two extragalactic sources, IC 310 and NGC 1275. Currently, the following three models are accepted as a feasible explanation for minute-scale variability: (i) external cloud in the jet, (ii) relativistic blob propagating through the...
PKS 2155-304 is a blazar located in the Southern Hemisphere, monitored with the High Energy Stereoscopic System (H.E.S.S.) at very high energy (VHE) gamma rays every year since 2004. Thanks to the large data set collected in the VHE range and simultaneous coverage in optical, ultraviolet, X-ray and high energy gamma-ray ranges, this object is an excellent laboratory to study spectral and...
We present results of optical variability study of 44 newly identified blazars and blazar candidates behind the Magellanic Clouds (Żywucka et al. 2018). The sample contains 27 flat spectrum radio quasars (FSRQs) and 17 BL Lacertae objects (BL Lacs), but only nine of them are recognized as blazars, while the classification of 35 objects is still uncertain. All objects possess high photometric...
The Spectral Energy Distribution (SED) of BL Lacs is usually modelled assuming that the momentum distribution of the non-thermal particles is isotropic. The modelling of the SED typically suggests the presence of strongly sub-equipartition magnetic fields in the emission region, which contradicts the paradigm of dynamically important magnetic fields in AGN jets. I will argue that the...
AGN are believed to be potential sites of ultra-high energy (UHE) cosmic ray acceleration. I will highlight observational findings as well as requirements on source energetics, and then discuss the relevance of different acceleration sites and mechanisms, such as black hole gap or large-scale jet shear acceleration.
The combined effects of supernova explosions and stellar winds produce a hot bubble in the central regions of starburst galaxies. As the bubble expands, it can outbreak into the galactic halo driving a superwind that transports hot gas and fields to the intergalactic space. I present estimates of cosmic ray generation and gamma-ray emission in this large-scale wind.
TBD
Relativistic radio jets create large-scale lobes -- the extragalactic footprints of accretion onto supermassive black holes, central to radio-loud active galaxies. In these dynamic and energetic structures, the phenomenon of spectral ageing occurs -- the progressive steepening of the radio spectrum in the lobes due to radiative losses. Recent advances in computing capabilities have enabled...
