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Samuel Patrick

Samuel Patrick
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Summary

My research focuses predominantly on simulating the direct collapse of cosmological halos, the leading hypothesis for the extreme masses of high redshift quasars. My research group performed the longest running simulations of such phenomena using the Enzo hydrodynamic cosmology code, with dark matter halos spanning a range of assembly histories, from initial coalescence out to beyond 3 Myr in some instances. This hence allowed us to observe the long-term behaviour of the resulting accretion disks over many dynamical times and assess any distinct trends. This also enabled us to accrue accretion rates over the entirety of central object's evolution into a supermassive star (SMS) and subsequent collapse into a black hole (BH). In feeding this data to stellar evolution models, we self-consistently determined the initial masses for a spectrum of black holes and confirmed their existence in the cosmological flows that create them. We were also able to evaluate any effect of host halo properties on the disk environment and BH mass.

I have also performed exploratory studies on the effect of X-ray radiation from these BHs on the immediate cosmological environment and confirmed that they create a HII region whose expansion competes against the accretion pressure of the infalling gas. I've assessed the observabilty of this radiation as well as the infra-red flux from the progenitor SMS for upcoming high redshift and radio surveys.

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