Faint progenitors of luminous $z \sim 6$ quasars: why don't we see them?

Understand

Observational searches for faint active nuclei at $z > 6$ have been extremely elusive, with a few candidates whose high-$z$ nature is still to be confirmed.

• Interpreting this lack of detections is crucial to improve our understanding of high-$z$ supermassive black holes (SMBHs) formation and growth.
• In this work, we present a model for the emission of accreting BHs in the X-ray band, taking into account super-Eddington accretion, which can be very common in gas-rich systems at high-$z$.
• We compute the spectral energy distribution for a sample of active galaxies simulated in a cosmological context, which represent the progenitors of a $z \sim 6$ SMBH with $M_{\rm BH} \sim 10^9 \, M_\odot$.