The Perseus galaxy cluster is known to present multiple and misaligned pairs of cavities seen in X-rays, as well as twisted kiloparsec-scale jets at radio wavelengths; both morphologies suggest that the AGN jet is subject to precession. In this work
we performed 3D hydrodynamical simulations of the interaction between a precessing AGN jet and the warm intracluster medium plasma, which dynamics is coupled to a NFW dark matter gravitational potential. The AGN jet inflates cavities that become buoyantly unstable and rise up out of the cluster core. We found that under certain circumstances precession can originate multiple pairs of bubbles. For the physical conditions in the Perseus cluster, multiple pairs of bubbles are obtained for a jet precession opening angle > 40 degrees acting for at least three precession periods, reproducing well both radio and X-ray maps. Based on such conditions, assuming that the Bardeen-Peterson effect is dominant, we studied the evolution of the precession opening angle of this system. We were able to constrain the ratio between the accretion disc and black hole angular momenta as 0.7 - 1.4. We were also able to constrain the present precession angle to 30 - 40 degrees, as well as the approximate age of the inflated bubbles to 100 - 150 Myrs.
NGC1275, the central galaxy in the Perseus cluster, is the host of gigantic hot bipolar bubbles inflated by AGN jets observed in the radio as Perseus A. It presents a spectacular $H{alpha}$-emitting nebulosity surrounding NGC1275, with loops and fila
ments of gas extending to over 50 kpc. The origin of the filaments is still unknown, but probably correlates with the mechanism responsible for the giant buoyant bubbles. We present 2.5 and 3-dimensional MHD simulations of the central region of the cluster in which turbulent energy, possibly triggered by star formation and supernovae (SNe) explosions is introduced. The simulations reveal that the turbulence injected by massive stars could be responsible for the nearly isotropic distribution of filaments and loops that drag magnetic fields upward as indicated by recent observations. Weak shell-like shock fronts propagating into the ICM with velocities of 100-500 km/s are found, also resembling the observations. The isotropic outflow momentum of the turbulence slows the infall of the intracluster medium, thus limiting further starburst activity in NGC1275. As the turbulence is subsonic over most of the simulated volume, the turbulent kinetic energy is not efficiently converted into heat and additional heating is required to suppress the cooling flow at the core of the cluster. Simulations combining the MHD turbulence with the AGN outflow can reproduce the temperature radial profile observed around NGC1275. While the AGN mechanism is the main heating source, the supernovae are crucial to isotropize the energy distribution.
Polarimeric maps have been used on the characterization of the magnetic field in molecular clouds. However, it is difficult to determine the 3-dimensional properties of these regions from the projected maps. In that case, numerical simulations can be
used as benchmarks for polarimetric measurements, and evetually reveal more about the interplay of turbulence and the magnetic field lines. In this work we provide a number of MHD numerical simulations of turbulent molecular clouds and created their synthetic dust emission polarization maps, varying the direction of the observer. We determined the correlation of emission intensity and polarization degree for the simulated models. We were able to reproduce the decay on polarization degree at denser regions without any assumption regarding the properties of the dusty component. The anti-correlation arises from the simple cancelation of the polarization vectors along the line of sight. This effect is amplified within denser regions as the magnetic field configuration becomes more complex. We studied the probability distribution, the power spectrum and the structure function of the polarization angles. These statistical analysis revealed strong defferences depending on the turbulent regime (i.e. sub/supersonic and sub/super-Alfvenic). Therefore, these methods can be used on polarimetric observations to characterize the dynamics of molecular clouds. We also presented a modified Chandrashekhar-Fermi method to obtain the intensity of the local magnetic field. The proposed formulation showed no limitations regarding orientation or turbulent regime.
