Astrophysical Cosmology

Faculty: Hopkins

This focus area seeks to understand the formation and evolution of galaxies, large-scale structure, black holes and quasars, stars and supernovae.


Galaxy Formation: While a 'consensus' description of the expansion history of the Universe has emerged in recent years, this has highlighted the limits of our understanding of the observable tracers of that history: galaxies, stars, and black holes. Understanding how the Universe evolves from relatively smooth "initial conditions" shortly after the Big Bang into the highly inhomogeneous, complicated, and non-linear structures we observe today is necessary both to address the origins of the Milky Way and to enable 'precision cosmology' measurements of galaxy correlation functions, neutral hydrogen in the early Universe, or massive galaxy clusters. The work in this area ties together basic questions in gravitational dynamics (and alternative theories of gravity and dark matter), collisional and collisionless fluid dynamics, stellar and black hole formation and evolution, chemical enrichment, and plasma physics.

Star Formation and Evolution: Stars represent the basic constituents of galaxies and our visible probes of most of the Universe, and as such the fields of galaxy and star formation have become increasingly indistinguishable in the last few years. Understanding star formation and massive stellar evolution, particularly under extreme conditions in the early Universe, is critical for understanding the properties and origin of galaxies, the formation of compact objects such as black holes and neutron stars, and ties together diverse questions in the general theory of turbulence, magneto-hydrodynamics, chemistry, and radiation-hydrodynamics. But it is also critical to understand high-energy phenomena such as supernovae and gamma-ray bursts, at the level necessary for their use as precision cosmological probes in current and future experiments (as well as their impact on galaxy formation and evolution).

Black Hole Formation and Evolution: Super-massive black holes, visible via their accretion energy as luminous quasars, represent some of the most visible and distant cosmological objects identified. Recently, the discovery of tight correlations between the properties of these black holes and the galaxies that host them has led to an explosion of work in studying how these small, highly relativistic scales are tied intimately to galactic and cosmological scales. Our work here considers both how cosmological processes such as galaxy mergers ultimately lead to black hole-black hole mergers and make predictions for new fundamental physics and cosmological probes to be tested with gravitational waves, and how, in turn, the growth and evolution of these black holes and associated processes such as accretion and relativistic jet formation can dramatically impact the masses and evolution of galaxies themselves.

Selected Recent Publications