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The Growth of the First Black Hole Seeds Fabio Pacucci In collaboration with: Andrea Ferrara (SNS), Marta Volonteri (IAP) EWASS 2015 – Tenerife 22/06/2015

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Key Question Credit: ESO/UKIDSS/SDSS ULAS J1120+0641 z = 7.085 Observations of SMBHs less than 800 Myr after the Big Bang: How is it possible? One possible solution: Direct Collapse Black Holes Formation possible only between. Requires: Atomic cooling ( ) halos Metal free gas ( Z=0 ) Strong Lyman-Werner ( 11.2 – 13.6 eV ) flux

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Questions we aim at answering How do the first black hole seeds shine? Physical Framework:Numerical Framework: Radiation-hydrodynamic code: Physically intuitive Spherical symmetry Intermediate spatial scales Solves Euler’s equations Frequency-integrated RT Cooling: BS and atomic Opacity: Thomson and B-F How do the first black hole seeds grow?

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How do the First Black Hole Seeds Grow? Black hole mass Accretion model Main growth parameters: Duty cycle Accretion rate depend on Standard Slim-disk Mass accreted: Time scale: Mass accreted: Time scale:

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The Spatial Structure of the Accretion Flow Transition Radius:

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A Bimodal Evolution of the Black Hole Seeds determines Continuous growth Intermittent growth

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How do the First Black Hole Seeds Shine?

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Upper Limit for the High-z Black Hole Mass Density AGN candidate at z = 6.26 Three AGN-candidates observed by the CDF-S at z>6 (Giallongo et al. 2015) Our upper limits (Pacucci et al. 2015): Standard Slim-disk

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Is CR7 the First Observed DCBH ? Hypothesis: CR7 is a DCBH (Pallottini et al. 2015) Main features of CR7 (Sobral et al. 2015): z=6.6 No metal lines Strong Lya and He II lines Strong Lyman-Werner flux (Elvis et al. 2009)

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Take-Away Points Slim-disk allows super-Eddington, continuous accretion of most ( ~ 100% ) of halo mass on timescales of order 10 Myr. The black hole growth may be bimodal, diversifying between low-mass ( ) and high-mass ( ) black holes. Upper limit on the z ~ 10 black hole mass density : --- The z=6.6 Lya emitter CR7 may be compatible with being the first Direct Collapse Black Hole ever detected.

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Time-evolving spectrum emerging from the host halo computed from: How do the First Black Hole Seeds Shine?

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