Conveners
Exploring the Cosmos: AGN-1: Parallel-5
- Hartmut Winkler
To understand extremely variable sources like Active Galactic Nuclei,
unbiased monitoring is of great importance. Often multi-wavelength
observations are triggered by flaring activities of the sources which
biases the overall data sample towards higher fluxes. Studying flux
correlations between different wavelengths or flux distributions, an
unbiased data sample is crucial. In the GeV...
While still outnumbered by sources with a small viewing angle, i.e. blazars, the population of misaligned active galactic nuclei (MAGN) has been steadily growing thanks to a decade of continuous all-sky monitoring by the Fermi-Large Area Telescope (LAT). The recently released Fermi-LAT fourth catalogue of AGN includes over 50 MAGN objects. These sources allow us to investigate different...
The flat-spectrum radio quasar QSO B1420+326 underwent an enhanced gamma-ray flux state seen by Fermi-LAT at the turn of 2019/2020. Compared to the low state both the position and luminosity of the two spectral energy distribution peaks changed by at least two orders of magnitude. The high state resulted in the discovery of the very-high-energy (>100 GeV) gamma-ray emission from the source by...
In recent work, we have developed a self consistent two-zone model of
time-dependent diffusive shock acceleration in the relativistic jets of
blazars and the resulting multi-wavelength spectral and variability
features. In this paper, we report the results of detailed fitting of
this model to recent multi-wavelength data from two blazars detected
during bright gamma-ray flares by...
Recent optical polarimetry monitoring programs have discovered optical polarization angle swings during blazar flares. Observations have shown that these swings are mostly simultaneous with Fermi gamma-ray flares. While angle swings are found in both flat spectrum radio quasars and BL Lac objects, blazars that have shown swings tend to be more active and brighter in gamma-rays. These features...
The discovery by the Large Area Telescope on-board the Fermi satellite of variable gamma-ray emission from radio-loud narrow-line Seyfert 1 galaxies (NLSy1) revealed the presence of an emerging third class of AGN with powerful relativistic jets. Considering that NLSy1 are usually hosted in late-type galaxies with relatively small BH masses, this finding opened new challenging questions about...
