Observational Studies of Rare Quasar Outflows: the FeLoBALs

Abstract

The absorption spectra of quasar outflows are studied in order to determine their kinematic and energetic properties and how they affect their host galaxy and its surroundings. If an outflow is sufficiently powerful to have an effect, a process known as active galactic nucleus (AGN) feedback, it can deplete the galaxy's gas reservoir required to produce stars, quenching its star formation rate and thus regulating the host galaxy's evolution. There is a growing body of work studying a rare type of broad absorption line (BAL) quasar that is rich in ion{Fe}{ii} absorption features, as well as ones from similar low-ionization species such as ion{Ni}{ii}, ion{Cr}{ii}, and ion{Fe}{iii}, known as FeLoBALs.

By analyzing the spectra of these objects using data from the Ultraviolet Echelle Spectrograph at the Very Large Telescope (VLT/UVES), we can determine several properties of these outflows, including the hydrogen number density $n_H$, the hydrogen column density $N_H$, and the hydrogen ionization parameter $U_H$. These values can in turn be used to calculate the distance of the outflow from its central source $R$, the mass outflow rate $dot{M}$, and the kinetic luminosity $dot{E}_k$. We have found that FeLoBALs can cover a wide parameter space of these properties.

In the first object, quasar SDSS J1130+0411, we find an FeLoBAL system with $dot{M}=4100$ solar masses per year, among the highest in the literature for any FeLoBAL to date. We additionally determine that this outflow has the capacity to contribute significantly to AGN feedback. We also find seven other outflow systems in this objects, including four outflows, two intervening systems, and a subcomponent of the main BAL. In the object SDSS J2107-0620, we find that the distance of the outflow is $R=0.21$ parsecs, closer to its central source than any other FeLoBAL to date. We also determine that its $dot{E}_k$ is several orders of magnitude too low to contribute to AGN feedback.