On the origin of the cosmic rays and gamma ray emission in the surrounds of Black Holes
Elisabete de Gouveia Dal Pino - IAG
The current detectors of gamma-ray emission have too poor resolution to determine whether this emission is produced in the jet or in the core of the low luminous AGNs (LLAGNs, particularly, radio galaxies) and microquasars. We have computed the power released by events of fast magnetic reconnection between the magnetic lines arising from the accretion disk and those of the black hole (BH) magnetosphere triggered by enhanced accretion, and found that this power is more than sufficient to reproduce the observed (core) radio and the gamma-ray luminosities in LLAGNs and microquasars. Moreover, this calculated power has a dependence with the BH mass of the sources that matches very well with the observed correlation between the luminosity and mass of these sources sustained for over 10 orders of magnitude in mass and power (for a sample including more than 200 sources). This match suggests a core emission for the VHE in these sources. Besides, based on 3D MHD simulations with test particles, we demonstrated that these suffer a first-order Fermi acceleration within the reconnection site at very efficient rates in the surrounds of the BHs. Then, employing this acceleration model driven by turbulent fast magnetic reconnection events in the core region, we computed the spectral energy distribution (SED) of several radio galaxies (M87, CenA, PerA) and microquasars (Cyg X1, Cyg X3) and found that these SEDs also match quite well with the observations, therefore strengthening the conclusions above in favor of a core emission for the VHE emission of these sources. In this seminar, I will discuss all these results and also the prospects to confirm these predictions with the future largest Gamma-Ray Observatory – the CTA (Cherenkov Telescope Array) – a Consortium of which IAG/USP and Brazil are partners.