Presentasjon av masteroppgave: Eirik Elias Prydz Fredborg

The multi-phase baryon cycle in a local infrared-luminous galaxy merger


AGN and stellar feedback play vital roles in the redistribution of gas in galaxies. Feedback can potentially affect the star formation rates and therefore the evolution of a galaxy. This thesis presents a spatially resolved analysis of the multi-phase outflow in a single local ultra luminous infrared galaxy (ULIRG). The work is presented as a possible building block for more detailed analyses of the connection between the feedback processes in galaxies with the goal of a better understanding of the processes driving galaxy evolution. Observations performed by the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Multi Unit Spectroscopic Explorer (MUSE) instrument of the Very Large Telescope (VLT) were used to study the local ULIRG, IRAS 20100 -4156. The molecular and ionised gas phases were studied, traced by the CO(1-0) and [OIII]5007 lines respectively. The galaxy is found to have outflows extending out to ∼ 5 and ∼ 7 − 8kpc for the molecular and ionised gas phases respectively. The gas phases do not follow the same kinematics. The molecular phase is reported to have approximately constant velocity as a function of distance to the galactic centre. The ionised gas is characterised by a clear trend of decrease in velocity at greater distances from the galactic centre. It is hypothesised that the cause for this lack of similarity in kinematics is that stellar feedback is a significant contributor to the molecular outflow and not the ionised outflow. Clear signs of oppositely directed outflows are reported, indicating that these outflows are driven by relativistic jets ejected by the central AGN. Peak outflow velocities for the molecular and ionized phases are ∼ 1000 and ∼ 1200km/s respectively. Spatially averaged velocities are determined to be 650 ± 60 and 776 ± 19km/s, consistent with previously published results on the source. I have estimated the outflow mass rate only for the molecular gas phase, which is believed to carry most of the mass of galactic outflows in (U)LIRGs. The total outflow mass rate is estimated to be M˙ outf (H2) = 1360 ± 340M⊙yr−1 , also consistent with results in the literature. The spatially resolved analysis estimate the outflow mass rates to be over 6 times greater in the regions closest to the galactic centre, than any other region. The methods of spatially resolved analysis show great potential, and would be beneficial to include in statistical analyses of samples of galaxies.


Supervisor:  Associate Professor Claudia Cicone, Institute of Theoretical Astrophysics, UiO


Intern. assessor:  Professor Øystein Elgarøy, Institute of Theoretical Astrophysics, UiO 

Extern. assessor:  Associate Professor Christian Vignali, Department of Physics and Astronomy "Augusto Righi", UNIBO



Publisert 18. mai 2022 13:13 - Sist endret 8. juni 2022 11:30