|Ph.D Student||Tomer Holczer|
|Subject||Ubiquitous Thermal Instability in Active Galactic|
|Department||Department of Physics||Supervisor||Full Professor Behar Ehud|
|Full Thesis text|
We Analyzed the spectrum of four AGNs (Active Galactic Nuclei): IRAS 13348?, NGC 3783, MCG-6-30-15 and NGC 3516. We fitted the data with our model and obtained from it the physical parameters: Each ion’s
column density, turbulent velocity and outflow velocity. We discovered new finding for some of the outflows: MCG-6-30-15 local (z=0) component that was thought to be part of the outflow as well as mass estimates (0.04 Solar
masses per year) and oxygen line correction using this AGN superior S/N spectra. We found two new previously unknown fast component in NGC 3516 that were not present in an earlier observation and only recently appeared.
We use the accurate measurement of ionic column density in order to develop the Absorption Measure Distribution (AMD) method to reconstruct the actual distribution of the column density in the plasma as a continuous function of temperature. We found a double peaked AMD for all the tested AGNs, namely all sources featured a deep minimum in column density consistent with no absorption from gas at temperatures of 4.5 < log T < 5 (K).
We interpret the minima as observational evidence for thermal instability in this temperature regime. Observing this minima in all objects we tested leads us to believe that all AGN outflows have this thermal instability, which arises from the typical physical conditions in the outflow, namely radiation field, densities and chemical abundances.