Rapid Black Hole Growth at the Dawn of the Universe: A Super-Eddington Quasar at z=6.6

Understand

We present the analysis of a new near-infrared (NIR) spectrum of a recently discovered $z=6.621$ quasar PSO J006+39 in an attempt to explore the early growth of supermassive black holes (SMBHs).

• This NIR (rest-frame ultraviolet, UV) spectrum shows blue continuum slope and rich metal emission lines in addition to Ly$\alpha$ line.
• We utilize the MgII line width and the rest frame luminosity $L_\text{3000\AA}$ to find the mass of SMBH ($M_\text{BH}$) to be $\sim 10^8 M_\odot$, making this one of the lowest mass quasars at high redshift.
• The power-law slope index ($\alpha_\lambda$) of the continuum emission is $-2.94\pm0.03$, significantly bluer than the slope of $\alpha_\lambda=-7/3$ predicted from standard thin disc models.