ausblenden:
Schlagwörter:
Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE
MPINP:
Hochenergie-Astrophysik Theorie - Abteilung Hofmann
Zusammenfassung:
The {\gamma}-ray data of Fermi-LAT on the giant lobes of Centaurus A are
analysed together with the high frequency radio data obtained with the Planck
satellite. The large {\gamma}-ray photon statistics, accumulated during seven
years of observations, and the recently updated Fermi collaboration software
tools allow substantial extension of the detected {\gamma}-ray emission towards
higher energy, up to 30 GeV, and lower energy, down to 60 MeV. Moreover, the
new {\gamma}-ray data allow us to explore the spatial features of {\gamma}-ray
emission of the lobes. For the north lobe, we confirm, with higher statistical
significance, our earlier finding on the extension of {\gamma}-ray emission
beyond the radio image. Moreover, the new analysis reveals significant spatial
variation of {\gamma}-ray spectra from both lobes. On the other hand, the
Planck observations at microwave frequencies contain important information on
spectra of synchrotron emission in the cutoff region, and thus allow
model-independent derivation of the strength of the magnetic field and the
distribution of relativistic electrons based on the combined {\gamma}-ray and
radio data. The interpretation of multiwavelength spectral energy distributions
(SEDs) of the lobes within a pure leptonic model requires strong enhancement of
the magnetic field at the edge of the south lobe. Alternatively, a more
complex, leptonic-hadronic model of the {\gamma}-ray emission, postulating a
non-negligible contribution of the {\pi}^0 -decay component at highest
energies, can explain the {\gamma}-ray data with a rather homogeneous
distribution of the magnetic field over the giant lobes.
