Highly accreting quasars show fairly distinctive properties in their optical, UV, and X spectra, and are easy to recognize because of their specific location in the quasar main sequence: they are the strongest optical FeII emitters. They show a surprisingly high rate of radio detections and, at variance with the classical radio-loud (jetted) sources, the origin of their radio emission is probably “thermal.” The chemical composition of the broad line emitting gas implies high metallicity values, above 10 times solar. A fraction of highly accreting quasars at intermediate and high redshift might therefore be in a particular evolutionary stage that is unobscured albeit still involving a contribution of nuclear and circum-nuclear star formation in their multifrequency properties.

高度吸积的类星体在其光学、紫外和 X 光谱中显示出相当独特的特性，并且由于它们在类星体主序列中的特定位置而易于识别：它们是最强的光学 FeII 发射器。它们显示出惊人的无线电探测率，并且与经典的无线电大声（喷射）源不同，它们的无线电发射的起源可能是“热的”。宽线发射气体的化学成分意味着高金属丰度值，超过太阳能的 10 倍。因此，一小部分处于中等和高红移的高度吸积类星体可能处于一个未被掩盖的特定演化阶段，尽管在它们的多频特性中仍涉及核和环核恒星形成的贡献。