The sustainable growth of the first black holes

Super-Eddington accretion has been suggested as a possible formation pathway of 10(9)M circle dot supermassive black holes (SMBHs) 800 Myr after the big bang. However, stellar feedback from BH seed progenitors and winds from BH accretion discs may decrease BH accretion rates. In this work, we study the impact of these physical processes on the formation of z similar to 6 quasar, including new physical prescriptions in the cosmological, data-constrained semi-analytic model GAMETE/QSODUST. We find that the feedback produced by the first stellar progenitors on the surrounding does not play a relevant role in preventing SMBHs formation. In order to grow the z greater than or similar to 6 SMBHs, the accreted gas must efficiently lose angular momentum. Moreover, disc winds, easily originated in super-Eddington accretion regime, can strongly reduce duty cycles. This produces a decrease in the active fraction among the progenitors of z similar to 6 bright quasars, reducing the probability to observe them.