Long-term spectral and temporal behavior of the high-frequency peaked BL LAC object 1ES 1959+650

: Backes M, Uellenbeck M, Hayashida M, Satalecka K, Tescaro D, Terzic T, Fuhrmann L, Nestoras I, Lahteenmaki A, Tornikoski M, Nieppola E, Bottcher M, Collmar W, Weidinger M

: 2012

AIP Conference Proceedings

: HIGH ENERGY GAMMA-RAY ASTRONOMY

: AIP CONF PROC

: 1505

: 522

: 525

: 4

: 0094-243X

DOI: https://doi.org/10.1063/1.4772312

In this context, 1ES 1959+650 has been regularly monitored by the MAGIC telescope since 2005. During these years, no significant variation in the VHE gamma-ray flux has been observed. The low energy part of this is in very good agreement with the high-energy part of the time-integrated energy spectrum as measured by Fermi-LAT. Based on this constant flux level in VHE gamma-rays, we assembled the time-integrated spectral energy distribution (SED) of 1ES 1959+650 from radio to VHE gamma-rays. Despite the non-variability at very high energies, significant flux and spectral variations have been observed at optical and X-ray frequencies in the meanwhile. Furthermore, the shape of the SED at high energy.-rays as measured by Fermi-LAT is essentially flat which cannot be explained by either conventional single-zone SSC models, or models invoking external radiation fields (EC).