Speaker
Mr
Rafal Wojaczynski
(Department of Astrophysics, University of Lodz)
Description
We present results of the analysis of the Fermi-LAT data from low-luminosity Seyfert galaxies, whose X-ray spectra are consistent with predictions of the hot flow (ADAF) model. We use our precise hot flow model (fully GR and with a Monte Carlo computation of radiative processes) to fit the X-ray data and then we estimate the gamma-ray flux from hadronic processes in the two-temperature plasma forming the flow. We find that the strongest gamma-ray signal may be expected from NGC 4258 and NGC 4151 and at the positions of both objects we find marginally significant signals, with sigma ~ 3. For all studied objects we derive upper limits (UL) for the gamma-ray flux. By comparing them with predictions of the ADAF model we find that the Fermi-LAT ULs strongly constrain non-thermal acceleration processes in hot flows (with the energy content in the non-thermal component of proton distribution amounting to at most ~10%) as well as the values of some crucial parameters, most significantly the magnetic field strength. We also find that the component above 4 GeV in the gamma-ray spectrum of Cen A may be due to hadronic emission from a hot accretion flow with parameters consistent with the above constraints. Under the assumption that this emission is produced by protons accelerated up to ~10^16 eV, as predicted by some acceleration models, we calculate the expected neutrino flux.
| Registration number following "ICRC2015-I/" | 954 |
|---|---|
| Collaboration | -- not specified -- |
Primary authors
Mr
Andrzej Niedzwiecki
(Department of Astrophysics, University of Lodz)
Mr
Fu-Guo Xie
(Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences)
Mr
Rafal Wojaczynski
(Department of Astrophysics, University of Lodz)
