27-31 August 2018
LVH, Luisenstraße 58, 10117 Berlin
Europe/Berlin timezone
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Contribution Talk

-3- Rudolf Virchow

H.E.S.S. observation of 3C 279 during optical and gamma-ray flares in 2017 and 2018


  • Carlo ROMOLI

Primary authors


Abstract content

The FSRQ 3C 279 (z=0.536) is a well known bright variable blazar. In recent years it has undergone several luminous outbursts detected at all wavelengths. Here we highlight the results of H.E.S.S. observations of two types of events of different nature during the year 2017 and in January 2018. The first Target of Opportunity followed the external trigger from the ATOM optical telescope that observed the source during a historical maximum in the R band, with a peak brightness of 13 magnitudes. Interestingly, this high optical flux was not mirrored at gamma-ray energies, which can place strong limits on the emission mechanism of this “orphan” flare. The 2018 observations were instead a reaction to a Fermi-LAT trigger for the second brightest flare ever seen from this source. We report a strong detection at very high energies during the decay phase of the Fermi-LAT flare. These events are presented in a multi-wavelength perspective in the context of the active phase that this source is undergoing since early 2017, with repeated outbursts.