Mag 12

The game of Blazars: multi-wavelength studies of jetted AGN

Giovedì 19 maggio alle ore 15:00, la Dr. Simona Paiano dell’INAF-IASF di Palermo terrà il web-seminar dal titolo: The game of Blazars: multi-wavelength studies of jetted AGN.


The Fermi Gamma-ray Observatory has discovered thousands of sources emitting from 100 MeV to 100 GeV. The vast majority of the extragalactic ones are jetted AGNs belonging to the class of blazars. Most of them are classified as BL Lac objects, characterised by a quasi-featureless optical spectrum where their very faint features can be detectable only with high quality optical spectra. This makes the determination of their distance extremely difficult, making it arduous to investigate their intrinsic physical properties and to understand and model the multi-wavelength Spectral Energy Distribution. Moreover, about one third of the detected Fermi sources are still not identified with optical objects, either because of the lack of counterparts in the gamma-ray error box or of multiple associations at other wavelengths. Although most of these sources are likely blazars, a new class of AGNs might be discovered.
To investigate the nature of these gamma-ray sources, we are carrying out extensive optical spectroscopic campaigns with telescopes of the 8-10m class. We secured high S/N spectra of more than 200 optical counterparts of TeV sources, neutrino blazars, blazar candidate sources and high-z BLLacs.
These observations allow us to assess the classification of the targets, to identify new blazars, to measure the redshift or set stringent lower limits and to find good potential candidates for future CTA observations. The results are of importance for the emission models of the sources, for the characterisation of the EBL and to shed light on their cosmic evolution and abundance in the non local Universe.

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