Presentation #337.09 in the session “AGN and Quasars 2”.
Quasars are growing supermassive black holes located at the centres of massive galaxies. These black holes are fuelled by accretion releasing a tremendous amount of energy as light. In a subset of quasars known as Broad Absorption Line Quasars (BALQs), this radiation can drive energetic outflows that appear as blue-shifted absorption lines in rest-frame ultraviolet (UV) spectra. With velocities of up to ~0.1c, these outflows can affect star formation via feedback within their host galaxies and furthermore may act to limit growth of the central black hole by slowing accretion. Around one-third of BALQ spectra show variability in depth or equivalent width of absorption lines, and in rare cases changes to the velocity profile. Variability studies provide constraints on the distance and geometry of the outflow, which have proved to be critical constraints for models of outflows. The cause of variability has been difficult to confirm, although is typically attributed to either (1) a change in ionization or (2) a change in covering fraction. We use SimBAL, a novel spectral synthesis code to provide an independent constraint on ionization state and physical properties of the gas. These additional constraints will help us to determine the cause of variability for individual BALQs. WPVS 007 is a nearby (z=0.02882), low-luminosity Narrow-Line Seyfert 1 galaxy (NLS1) galaxy that has shown dramatic variability in both X-ray and UV-optical spectra. We present new data from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) from 2017 as well as six previous epochs of UV spectroscopy. Data show the emergence of a broad absorption line with changing velocity and equivalent width. We fit each epoch using SimBAL to constrain the ionization state of the gas and confirm the cause of variability.