The most luminous blue quasars at $3.0<z<3.3$. I. A tale of two X-ray populations

Understand

(abridged) We present the X-ray analysis of a sample of 30 luminous quasars at $z\simeq3.0-3.3$ with deep XMM-Newton observations, selected from the SDSS-DR7 to be representative of the most luminous, intrinsically blue quasar population.

• By construction, the sample boasts a unique degree of homogeneity in terms of optical/UV properties.
• In the X-rays, only four sources are too faint for a detailed spectral analysis.
• Neglecting a radio-loud object, the other 25 quasars are, as a whole, the most X-ray luminous ever observed, with rest-frame 2-10 keV luminosities of $0.5-7\times10^{45}$ erg/s.