Astrophysics & Planetary Sciences Colloquium

Black hole accretion from the inside out

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Abstract: In the last several years, the combination of resolved event horizon scale images and large-scale computational models has led to new insights into black hole accretion. The main implication is that magnetic fields near the event horizon can become dynamically important, and I'll show that such a scenario provides a natural explanation for the high energy flares from our Galactic center black hole.

Gas flows and metal enrichment in and around simulated galaxies

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Abstract: Galaxies are intimately connected to the environments they live in. The haloes around them contain the gas reservoir from which the galaxies grow, while galactic outflows heat and enrich this circumgalactic medium (CGM). The elemental abundances of present-day stars are, in part, set by these cosmic gas flows. Using zoom-in cosmological simulations of galaxies, I will discuss the physical and observable properties of gas and stars in and around galaxies.

Field stars and their kinematics as a probe of massive star evolution and binary populations

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Abstract: Field massive stars are more easily identified and studied than those in crowded cluster environments.  While some massive stars may form in relative isolation, most are ejected from clusters via dynamical processes and supernova kicks in binary systems.  Since both mechanisms are driven by binarity in the massive star population, field stars and their kinematics probe the effects of binarity, which can strongly influence stellar evolution by the tr

Formed too Fast? Massive Galaxies at Cosmic Dawn

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Abstract: A growing number of surprisingly massive galaxies are now being found in the first ~billion years after the Big Bang that push the limits of theoretical predictions within Lambda-CDM. Unusually bright high-redshift galaxies discovered by JWST challenge our most fundamental models of how fast stars form. Some of them contain overly massive black holes whose formation is uncharted. Massive dusty starbursts found with ALMA are requiring new explanations about early dust production.