Published June 15, 2022 | Version v2
Thesis Open

Studying synthetic column density maps and absorption spectra from galactic wind models

  • 1. Univesity of Bologna
  • 1. Escuela de Ciencias Físicas y Nanotecnología, Universidad Yachay Tech
  • 2. Hamburg Observatory
  • 3. University of Bologna

Description

Galactic winds are multi-phase outflows that probe how feedback regulates the mass and metallicity of galaxies.  Their cold phase, mainly observable with absorption lines, is often detected hundreds to thousands of pc away from the galactic plane and with velocities of hundreds of km s1. To understand observations, it is important to theoretically study how such lines are produced via numerical simulations of cloud systems exposed to winds and starburst UV backgrounds. In this thesis we study the thermodynamics, ion populations, and ion absorption lines of cold and warm radiative clouds evolving from magnetised wind-cloud systems and an unmagnetised shock-multicloud model. We account for radiative cooling with two different cooling floors and magnetic fields with two different orientations.
In our wind-cloud simulations, cold clouds survive the interaction with the wind for longer, since they are less exposed to instabilities, than warmer clouds. Magnetic fields have a larger influence on warm clouds than in cold clouds. If transverse to the wind direction, the field creates a shield that confines the expansion of the cloud, delaying its evaporation. In our shock-multicloud simulation, cold gas at large distances is not accelerated by ram-pressure, but, instead, precipitates from mixed gas out of thermal equilibrium. To study ion populations and create synthetic spectra, we developed a flexible python interface to link our PLUTO simulations to TRIDENT via the YT-package infrastructure and CLOUDY. Our ion population analysis reveals that setting different cooling floors and magnetic fields affect the column densities of several ions. H\,{\sc i}, O\,{\sc vi}, Mg\,{\sc ii}, C\,{\sc iii}, and Si\,{\sc iv} are more sensitive to the cooling floors, and H\,{\sc i}, Mg\,{\sc ii}, C\, {\sc iii}, and Si\, {\sc iv} can also trace the initial magnetic field direction, making them good candidates for comparisons with observations.

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Thesis: https://amslaurea.unibo.it/25361/ (URL)