Description
Quasar winds are evident in rest-frame UV spectra in the form of blueshifted broad emission lines. How such winds are launched – and how such launching relates to the physical state of the accretion disc system that powers quasars – remains a key open question. SDSS-V follow-up of eROSITA sources is yielding a large quasar sample for which we have access to their wind properties and (via measurements of the X-ray, UV and optical emission) constraints on their accretion state. I will present new measurements for a sample 4000 quasars at redshifts 1.5-3.5 that quantify how the strength of quasar accretion disc-winds (from the CIV emission line) depends on both the strength of the UV ionising continuum (probed via HeII emission) and the X-ray properties derived from the eROSITA spectra (i.e., photon index and column density). We show that quasars with a given X-ray luminosity have a broad range of wind properties that appear to depend most strongly on the strength of the UV-bright inner accretion disc (revealed by the HeII emission line). A strong UV component can lead to over-ionisation of the wind such that the outflow strength is decreased. These results point to radiation-driven winds whose strength and presence are highly sensitive to the physical structure of the accretion system. The X-ray photon index and column density, however, do not appear to impact the strength of the wind. With this information in hand we can gain a new perspective of the wind properties of the X-ray selected quasars.
