Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2012-01-05
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
6 pages, 2 figures, proceedings of the INTEGRAL conference "The Extreme and Variable High Energy Sky", held on September 19-23
Scientific paper
NGC 4945 has an outstanding role among the Seyfert 2 active galatic nuclei (AGN) because it is one of the few non-blazars which have been detected in the gamma-rays. Here, we analyse the high energy spectrum using Suzaku, INTEGRAL and Fermi data. We reconstruct the spectral energy distribution in the soft X-ray to gamma-ray domain in order to provide a better understanding of the processes in the AGN. We present two models to fit the high-energy data. The first model assumes that the gamma-ray emission originates from one single non-thermal component, e.g. a shock-induced pion decay caused by the starburst processes in the host galaxy, or by interaction with cosmic rays. The second model describes the high-energy spectrum by two independent components: a thermal inverse Compton process of photons in the non-beamed AGN and a non-thermal emission of the gamma-rays. These components are represented by an absorbed cut-off power law for the thermal component in the X-ray energy range and a simple power law for the non-thermal component in the gamma-rays. For the thermal process, we obtain a photon index of Gamma=1.6, a cut-off energy of Ec ~ 150 keV and a hydrogen column density of NH = 6e24 1/cm**2. The non-thermal process has a photon index of Gamma=2.0 and a flux of F(0.1-100 GeV) = 1.4e-11 erg/cm**2/sec. The spectral energy distribution gives a total unabsorbed flux of F(2 keV - 100 GeV) = 5e-10 erg/cm**2/sec and a luminosity of L(2 keV - 100 GeV) = 9e41 erg/sec at a distance of 3.7 Mpc. It appears more reasonable that the gamma-ray emission is independent from the AGN and could be caused e.g. by shock processes in the starburst regions of the host galaxy.
Beckmann Volker
Mattana Fabio
Menzel Marie-Luise
No associations
LandOfFree
AGN emission processes of NGC 4945 in the X-rays and gamma-rays does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with AGN emission processes of NGC 4945 in the X-rays and gamma-rays, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and AGN emission processes of NGC 4945 in the X-rays and gamma-rays will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-609406