An X-shooter insight into dust-reddened quasars

An important fraction of quasars are red at optical wavelengths, indicating (in the vast majority of cases) that the accretion disc is obscured by a column of dust . In recent work by our group, we have shown fundamental differences in the radio properties of SDSS optically selected red quasars, which cannot be explained with a simple viewing angle hypothesis (Klindt et al. 2019, Fawcett et al. 2020, Rosario et al. 2020). In our latest work, we use VLT/X-shooter spectroscopy of a sample of red and typical quasars to gain insight into these differences. We confirm that dust reddening is the main cause of the red colours, and from fitting the [OIII] emission line we find stronger evidence for outflows in red quasars, possibly affecting the host galaxy. We confront our spectra against accretion disc models and confirm that red quasars are powered by standard thin-disc accretion. The lack of any fundamental differences between red and blue quasars in terms of simple accretion properties suggests external processes, such as outflows, may be key features that distinguish the two populations. Red quasars may therefore represent an important phase in galaxy evolution