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James Bonifacio
Department of Physics
Case Western Reserve University
Giving the Graviton a Mass
In general relativity, the gravitational force is mediated by a massless spin-2 particle…the graviton. In fact, the structure of general relativity and
its interactions with other particles are largely fixed by this requirement. However, there are still many open questions about the behavior of gravity,
both at short and long distances, which motivates the exploration of theories that deform general relativity. One such question is whether the graviton in
our universe can have a small but nonzero mass. In this talk I will review some of the challenges and successes in constructing theories of massive
gravitons and discuss some recent experimental and theoretical results that constrain such theories.
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Shanti Bhushan
Mechanical Engineering
Mississippi State University
Computational Fluid Dynamics: Turbulence Modeling and Applications
Turbulence/transition modeling is a primary source of uncertainty in computational fluid dynamics, and this problem remains unsolved despite over one
hundred years of scientific research. The talk will focus on an overview of author's ongoing research in transition/turbulence modeling and applications.
The key modeling topics that will be discussed are: identification of transition onset marker for bypass transition; modeling subgrid scale energy
transfer using algebraic models; and potential of machine learning for turbulence modeling. The key application topic will focus on role of turbulence on:
growth of vortical structures for ship flows; heat transfer; structural deformation for shock boundary layer interaction; growth of rotor wake; and
propagation of acoustic waves. Some open question in transition/turbulence will also be emphasized.
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Dustin Madison
Department of Physics and Astronomy
West Virginia University
Advancing the Capabilities of Nanohertz Gravitational Wave Astronomy
After fifteen years of ongoing effort to precisely monitor the most stable millisecond pulsars known, the North American Nanohertz Observatory for
Gravitational Waves (NANOGrav) is poised, within the next five years, to detect gravitational waves (GWs) in an entirely unexplored range of frequencies.
The initial detection will be just the beginning of a sustained campaign to characterize the nanohertz GW sky. I will discuss important fundamental
features of the astrophysics underpinning and motivating NANOGrav's efforts and certain unavoidable shortcomings of pulsar timing array investigations. I
have a plan to ameliorate these shortcomings by synthesizing pulsar timing data and precise astrometric surveys from instruments such as the Gaia space
telescope, a program that could powerfully augment both the immenent and long-term scientific returns of nanohertz GW astronomy. Finally, I will discuss a
new and interesting way that astrometric measurements could enable the detection of GW memory, a theoretically important signal sought after by GW
astronomers across the frequency spectrum.
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Yuan Li
Department of Astronomy
University of California — Berkeley
Supermassive Black Hole Feedback in the Centers of Massive Galaxies and Galaxy Clusters
The centers of massive galaxies and galaxy clusters contain hot plasma that loses its energy rapidly through radiation of X-ray photons. The energy loss
is thought to be compensated for by the energy input from the supermassive black holes (SMBHs) in the centers of these systems, via a process often termed
as "AGN feedback". In this talk, I will review the state of the field, and discuss what we have learned from numerical simulations in the past few years,
including how AGN jets deposit their energy to the surrounding medium, and how they affect cooling and star formation. I will also talk about my recent
analysis of optical and ALMA observations of multiphase filaments in cluster centers, which not only improves our understanding of AGN feedback, but also
puts unprecedented constraints on microscopic transport processes in the weakly-collisional, magnetized intracluster plasma.
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