Elismar Lösch
My poster is going to be about the work I’ve been developing during my undergrad research in Astrophysics, where we are using numerical methods to simulate the galactic system in interaction Arp 245, in order to determine how the collision (merger) which is happening in this system could explain the triggering of phenomena such as active galactic nuclei (AGNs) and starbursts within the galaxies envolved. The idea is basically that, when galaxies collide, tidal forces disrupt the intergalactic gas of the galaxies taking it to the center of them. The gas can then find a supermassive black hole, form an accretion disk and yield an AGN, a process which can outshine its entire host galaxy. By now, we studied some simulations taken from a library called GalMer and applied a code called GADGET-3 to run once more one of them. We are analysing quantities such as the inflow of gas to the galactic centers, the AGN luminosities associated with such inflows and star formation rate of the galaxies during the simulations. I’m also going to present how we are constructing the initial conditions for a new, more reliable simulation based on observational data of the galaxies.
Our methodology consists of a first exploration of three simulations which more closely resembles Arp 245 taken from the GalMer library of merger simulations. With the simulations we then computed gas inflows towards galactic centers during the interaction and AGN luminosities associated. We also re-ran one of them with the code GADGET-3 and are currently building a new, more data-driven model for the system. For the methodology section I show a panel of snapshots of the three simulations we studied at four different stages of the merger: they start the same, but evolve quite differently.
Some of our results so far include that the simulation we call “Orbit type 5” - the one with intermediate value of orbital angular momentum - yields a gas inflow enough to explain the AGN luminosity observed in NGC 2992 at the current stage of the merger, which is not the case with the other two. We also observe that the gas inflow peaks around the closest approximation between galaxies during the merger. Finally, we concluded that the inflows and star formation rate for the GalMer and GADGET-3 simulations showed important differences. These results are shown in three plots: one is a panel showing the GalMer simulations’ gas inflows through four different spherical surfaces around galactic centers. The second shows AGN luminosities considering an accretion rate of the supermassive black hole equal to the gas inflow at 10pc. The third is similar to the first, but now showing the inflow of gas for just one of the simulations to compare the outcome of GalMer and GADGET-3 runs.
We are currently working with observational data of the system to obtain the density profile parameters of the different galaxy components in order to build a more accurate initial condition of the merger. We are also running simulation tests of the galaxies in isolation in order to tell the merger effect from internal effects on the galaxies. Future work includes obtaining the system’s orbital parameters and running a new simulation using this initial condition. A last figure shows the result of the fit of brightness profiles for the galaxy NGC 2992, which will be applied to get the density profiles for the different structural components of the galaxy.