Testing two-component models on very high-energy gamma-ray-emitting BL Lac objects
Loading...
Access rights
openAccess
URL
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
View publication in the Research portal (opens in new window)
View/Open full text file from the Research portal (opens in new window)
Other link related to publication (opens in new window)
Date
2020-08-01
Department
Major/Subject
Mcode
Degree programme
Language
en
Pages
29
Series
Astronomy & Astrophysics, Volume 640
Abstract
Context. It has become evident that one-zone synchrotron self-Compton models are not always adequate for very high-energy (VHE) gamma-ray-emitting blazars. While two-component models perform better, they are difficult to constrain due to the large number of free parameters. Aims. In this work, we make a first attempt at taking into account the observational constraints from very long baseline interferometry (VLBI) data, long-term light curves (radio, optical, and X-rays), and optical polarisation to limit the parameter space for a two-component model and test whether or not it can still reproduce the observed spectral energy distribution (SED) of the blazars. Methods. We selected five TeV BL Lac objects based on the availability of VHE gamma-ray and optical polarisation data. We collected constraints for the jet parameters from VLBI observations. We evaluated the contributions of the two components to the optical flux by means of decomposition of long-term radio and optical light curves as well as modelling of the optical polarisation variability of the objects. We selected eight epochs for these five objects based on the variability observed at VHE gamma rays, for which we constructed the SEDs that we then modelled with a two-component model. Results. We found parameter sets which can reproduce the broadband SED of the sources in the framework of two-component models considering all available observational constraints from VLBI observations. Moreover, the constraints obtained from the long-term behaviour of the sources in the lower energy bands could be used to determine the region where the emission in each band originates. Finally, we attempt to use optical polarisation data to shed new light on the behaviour of the two components in the optical band. Our observationally constrained two-component model allows explanation of the entire SED from radio to VHE with two co-located emission regions.Description
Keywords
galaxies: active, galaxies: jets, BL Lacertae objects: general, astronomical databases: miscellaneous, radiation mechanisms: non-thermal, gamma rays: galaxies, ACTIVE GALACTIC NUCLEI, SHEATH POLARIZATION STRUCTURES, MULTIWAVELENGTH OBSERVATIONS, X-RAY, RELATIVISTIC JETS, TEV BLAZARS, CROSS-CORRELATIONS, LACERTAE OBJECTS, COMPLETE SAMPLE, 1ES 1959+650
Other note
Citation
Hovatta, T & MAGIC Collaboration 2020, ' Testing two-component models on very high-energy gamma-ray-emitting BL Lac objects ', Astronomy & Astrophysics, vol. 640, A132 . https://doi.org/10.1051/0004-6361/202037811