| Abstract [eng] |
The masses of supermassive black holes in galaxies correlate with the galaxies' characteristic parameters. Outflows are one way to explain $M_{\mathrm{SMBH}} - \sigma$ and other similar correlations. Outflows are a form of feedback and are produced by the active galactic nucleus (AGN) creating winds. The AGN wind pushes gas that travels away from the centre of the galaxy and can be observed. Some outflows are peculiar in that the AGN luminosity and outflow parameters are uncorrelated. These outflows can be called fossil, due to the fact that by the time they are observed, the AGN has become inactive. In this work I run hydrodynamical simulations of AGN feedback on idealised turbulent gas shells, with multiple uniformly generated AGN episodes, and compare them to less realistic ones where AGN episode is continuous for 1 Myr. The aim of this thesis is to investigate the evolution of galactic outflows with multiple AGN episodes. The conclusions are the following: \begin{enumerate} \item In simulations, with multiple AGN episodes, the outflows are not as prominent compared to continuous AGN episode simulation in terms of size and distance they travel from the center. In one of the simulation with multiple AGN episodes outflows fade rather quickly, though they can reach radial velocities of $v_{\rm rad} > 300 \ \rm{km \ s}^{-1}$ (see Figure \ref{fig:R4A velocity}). They reach distances of around $r=0.6$ kpc before they begin to fade. However, they are more concentrated near the center at $r < 0.3$ kpc. Continuous AGN simulations have larger and more massive outflows reaching around $r \sim 1.2$ kpc before begining to fade. \item In a simulation with multiple AGN episodes, mass flow rates peak values are $\dot{M} = 97 \ \msun ~{\rm yr}^{-1}$ at $r=0.3$ kpc, while $t = 1.5$ Myr. Other simulations show lower peak values of mass flow rates, but in general, their momentum and energy rates are similar. Next, the average mass outflow rates were calculated for all of the AGN episodes and periods of quiescent AGN. In some simulations, when the AGN is off, mass flow rates on average can be higher that the ones with AGN on, in others it can be the opposite. At 0.3 kpc averaged mass flow rates vary relatively more than at 0.6 kpc, however they are greater and reach up to $\sim 39 \ \msun ~{\rm yr}^{-1}$. \item I separated the mass flow rates into cold, warm, and hot gas components, when analysing the radial mass flow rate dependency: the outflows during AGN inactivity phase (multiple AGN episodes simulation) are mostly comprised of cold ($T < \mathrm{5} \times 10^4 \ \mathrm{K}$) gas component, but hot ($T > 10^7 \ \mathrm{K}$) outflows are still prevalent and reach $\dot{M} = 30 \ \msun ~{\rm yr}^{-1}$ at $r=0.2$ kpc. After 100 kyr mostly hot gas transfer the mass from the center, while maintaining $\dot{M} = 38 \ \msun ~{\rm yr}^{-1}$. Regarding the outflowing mass (in simulations with multiple AGN episodes) fast moving outflows ($v_{\rm rad} > 3 \times \sigma$) are hot and reach the average temperatures of $T_{\rm avg}\simeq 10^{7.2}$ K. They also comprise from 19\% to 26\% of generally filtered outflowing mass ($v_{\rm rad} > \sigma$). Continuous AGN simulations have peak outflowing mass of $M = 1.3\times 10^8 \msun$ with ($v_{\rm rad} > \sigma$). \end{enumerate}. |
