Supermassive black hole masses may be overestimated for distant quasars

Supermassive black hole masses may be overestimated for distant quasars

This paper draws an analogy between ultraluminous X-ray sources (ULXs) and distant quasars to suggest that the high black hole mass estimates for quasars may be too large. Like ULXs, quasars could be 'beamed' with anisotropic emission if fed at super-Eddington rates, causing observers to overestimate their luminosities and masses. Their emission line properties would still match unbeamed quasars. So quasars may have lower masses that grew from stellar remnants, rather than requiring massive early seeds.