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We present a qualitative search for ultra-fast outflows (UFOs) in excessvariance spectra of radio-quiet active galactic nuclei (AGN). We analyse 42sources from the Tombesi et al. (2010) spectroscopic UFO detection sample, andan additional 22 different sources from the Kara et al. (2016) variabilitysample. A total of 58 sources have sufficient observational data fromXMM-Newton EPIC-pn and variability for an excess variance spectrum to becalculated. We examine these spectra for peaks corresponding to variableblue-shifted H- and He-like ion absorption lines from UFOs. We find goodevidence for such outflows in 28% of the AGN sample and weak evidence in afurther 31%, meaning that $\sim$ 30-60% of the AGN sample hosts such UFOs. Themean and median blue-shifted velocity is found to be $\sim$ 0.14c and 0.12c,respectively. Current variability methods allow for a fast, model-independentdetermination of UFOs, however, further work needs to be undertaken to bettercharacterize the statistical significance of the peaks in these spectra by morerigorous modelling. Detecting good evidence for variable UFO lines in a largenumber of sources also lays the groundwork for detailed analysis of thevariability timescales of the absorbers. This will allow us to probe theirdensities and hence distances from the central super-massive black hole.

Searching for Ultra-fast Outflows in AGN using Variability Spectra