[Si VI] luminosity for Arp 220 and a sample of nearby AGN. Top panel: [Si VI] luminosity as a function of redshift for the sample of BASS AGN with detected (purple circles) and undetected (green squares) [Si VI] line from Lamperti et al. (2017). Arp 220 measurements are represented by red stars. For sources with undetected [Si VI] lines, we provide 3σ upper limits (illustrated with arrows). Bottom panel: [Si VI] luminosity as a function of intrinsic X-ray (2−10 keV) luminosity for the same sources as reported in the top panel. The dashed line indicate the linear relation between L([Si VI]) and L_{2 − 10 keV int} obtained by Lamperti et al. (2017, not considering upper limits). X-ray luminosity upper limits for the nuclei of Arp 220 are taken from Paggi et al. (2017).