1. HOW WHAT Conclusions Barausse E., 2012, MNRAS, 423, 2533 De Rosa G., Decarli R., Walter F.,Fan X., Jiang L., Kirk J., Pasquali A., Rix H. W., 2011, ApJ, 739, 56; Fan X., Strauss M.A., Schneider D.P., Becker R.H., White R.L., Haiman Z., Gregg M., Pentericci L., et al., 2003, AJ, 125, 1649; Menci N., Fontana, A., Giallongo, E., Salimbeni, S. 2005, ApJ, 632, 49 Menci N., Fiore F., Puccetti S., Cavaliere, A.,2008, ApJ, 686, 219 Mo H. J., Mao S., White S. D. M., 1998, MNRAS, 295, 319 Sadowski, A. 2009, ApJS, 183, 171 Valiante R., Schneider R., Salvadori S., Bianchi S., 2011, MNRAS, 416, 1916; Valiante R., Schneider R., Salvadori S., Gallerani S., 2014, MNRAS, 444, 2442; Yoo J., Miralda-Escude', J., 2004, ApJ, 614, L25 We investigate the role of super-Eddington accretion onto BH progenitors of high-z quasars. We use a modified version of the code GAMETE/QSODUST introduced by Valiante et al. (2011, 2014) aimed to study the formation and evolution of high redshift (z>5) quasars. The code reconstructs the hierarchical merger histories of dark matter halos hosting the quasars and consistently follows the build up of galaxies and their central black holes via both mass accretion and mergers. The evolution of the black hole and its host galaxy proceeds hand-in-hand and is regulated by the feedback from the active nucleus. In the model presented here, we have improved the description of the physical processes driving star formation in the host galaxy and mass accretion onto the central black hole. We investigate how these physical processes affect the co- evolution of the system and if and when the black hole progenitors of the final super-massive black hole accrete at super-Eddington rates. WHY Super-Eddington growth of the first black holes Edwige Pezzulli 1,2,3, ★, Rosa Valiante 1, Raffaella Schneider 1, Valeria Ferrari 2,3 1 INAF/Osservatorio Astronomico di Roma, Via di Frascati 33, 00040 Monte Porzio Catone, Italy 2 Dipartimento di Fisica, “Sapienza”, Universita’ di Roma, P.le Aldo Moro 2, 00185, Roma, Italy 3 INFN, Sezione di Roma I, P.le Aldo Moro 2, 00185 Roma, Italy IGM Hot gas Star Formation BH accretion AGN reheating feedback SNe reheating feedback AGN ejection SNe ejection Mass accretion Cooling Seeding metal/dust enrichment Minor Merger Bulge formation Asymmetric GW momentum: kick velocities Major Merger Hierarchical merger histories of a 10 13 M sun DM halo at z = 6.4 (Valiante et al 2011, 2014) Formation of disk via gas cooling (Mo, Mao & White 1998) BH seeds from POP III remnants of M seed = 100 M  (Tanaka & Heiman 2009) BH growth via accretion and via coalescence in DM halos major mergers (DM mass ratio > ¼) (Menci et al 2008, Valiante et al 2014) Kick velocities of newly-formed BH from coalescence (Tanaka & Heiman 2009, Yoo & Miralda-Escude 2004) Formation of bulge via major merger (Barausse 2012) Bursted and quiescent SFR in both disk and bulge (Menci et al 2005) SNe and AGN feedback (Menci et al 2008) Metal and dust enrichment provided by AGB and SNe (Valiante et al 2011, 2014) We reproduce the observed properties of one of the best studied quasar, SDSS J1148+5251, whose BH mass and Eddington ratio are: Averaging on 10 independent merger histories, we aim to answer the questions: is it necessary to have Super- Eddington accretion to build up J1148? If yes, what are the environments in which this occurs? z M BH (M  )η Edd 0.5 6.44.9 x 10 9 Fan et al. 2003 De Rosa et al. 2011 Fig.1 shows that the contribution of the cumulative mass from BH seeds is negligible. This is a consequence of the large accretion rates experienced by the BHs, whose evolution is shown in Fig. 2 (in both panels the solid line is the average and the shaded region is the 1-σ dev). Most of the BH accrete with η Edd > 4. This fraction decreases with time and at z < 8 all the BHs accrete with η Edd ≤ 1. Super-Eddington accretion events occur in two kind of environments: 1.Onto BH seeds (M BH = 100 M  ) at z > 16 with BH accretion rates [10 -4 – 5] M  /yr; 2.On intermediate mass BHs [10 4 -10 7] M  at z > 8 with BH accretion rates (0.1 – 10) M  /yr We find that super-Eddington accretion drives an early build-up of the super- massive BH. The low radiative efficiencies favor gas retention. The gas can be re- heated by AGN feedback but then cools again sustaining BH accretion. The super- Eddington accretion events that give the largest contribution to the final BH mass occur at redshits 12 < z < 18 onto intermediate mass BHs. Compared to scenarios with Eddington- limited BH growth, we find that high-z quasars follow a symbiotic evolution, where the nuclear BH and the host galaxy grow at the same rate. Due to their low masses, BH seeds have the larger L/L Edd, which then decrease with BH mass and time. The radiative efficiencies of super-Eddington accreting events are < 0.01. REFERENCES Cold gas Fig. 1: evolution of the nuclear BH mass Fig. 2: evolution of the BH accretion rate Fig. 5: L/L Edd distribution of accretion events BH Fig. 4: BH mass distribution of accretion events Fig. 3: redshift distribution of accretion events The slim disk solution for super-critical accretion: We consider optically thick, stationary slim disks and we compute the radiative efficiency as, where the bolometric luminosity, L bol, is computed adopting the fit presented by Madau et al. (2014) and based on numerical simulations of relativistic slim disks (Sadowski 2009), where A(a), B(a) and C(a) are functions of the spin parameters a.