Comprehensive Model for the Formation-Evolution of Massive Cosmic Systems: The Answer is Blowing in the Wind

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Massive cosmic halos, a category that includes the most massive galaxies in the universe as well as galaxy groups and clusters, are remarkable systems. With masses ranging from an equivalent of 10,000 billion to a mind-boggling million billion suns, these halos are the largest, most massive gravitationally bound objects in the cosmos. The majority of their mass is dark matter. Of the visible matter that comprises these systems, the bulk is in the form of million degrees (or more) hot, X-ray emitting gas. The halos host gargantuan black holes that feed off the ambient gas and propel powerful jets that extend out a hundred thousand light-years or more. How did these systems we observe today form? What processes have shaped them? One reason why these are pressing questions is that the massive halos collectively host >50% of the galaxies in the universe and it is just not possible to explain why the observed galaxies exhibit the properties they do without knowing how a significant fraction's evolution is impacted by the extreme environment they reside in. Another reason is that the massive halos are the youngest of the cosmic structures to have formed. In fact, the most massive still bear the imprints of the conditions that led to their formation and therefore, have been identified as important probes of the geometry and the expansion of the universe. The use of galaxy clusters as cosmological probes, however, depends critically on how well we understand why clusters in the local universe look the way they do, and what they looked like at an earlier epoch. My research focuses on developing realistic model that seeks to address the above issues. This modeling involves carrying out state-of-the-art computer simulations on powerful supercomputers to replicate "virtually" the universe's 13.7 billion year history and attempt to describe, as thoroughly as possible within the framework of the model, the incredibly complex web of inter-related physical processes that influence the characteristics of the massive halos. These processes range from those that (a) shape the flow of convergent dark matter flows and give rise to increasingly larger cosmic structures with time; (b) govern the formation of galaxies, and the birth, life and death of stars therein; and (c) describe the action of the hot gas on the galaxies as the latter speed through the former; to those that (d) are responsible for winds that transport stellar detritus as well as the explosive energy released by dying stars out of the galaxies and into the wider environment; (e) regulate the response of supermassive black holes as they capture and draw in gas from their surroundings; and more. Numerical simulations are the only way of unraveling this web. The challenge lies in ensuring that the simulations correctly capture the physics involved, and doing so within the constraints imposed by today's computational limitations requires ingenuity, creativity and insight.