The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Spring 2020

Unless noted otherwise, Tuesday Colloquia are at 4:00 PM
with refreshments served 15 minutes before each colloquium.

Scheduling for additional seminars will vary.

Date/Place Speaker Title (and link to abstract)
Tue, Jan 21
Lewis 101
James Bonifacio
Department of Physics
Case Western Reserve University
Giving the Graviton a Mass
Tue, Jan 28
Lewis 101
Shanti Bhushan
Mechanical Engineering
Mississippi State University
Computational Fluid Dynamics: Turbulence Modeling and Applications
Thurs, Jan 30
Lewis 101
Dustin Madison
Department of Physics and Astronomy
West Virginia University
Advancing the Capabilities of Nanohertz Gravitational Wave Astronomy
Tue, Feb 4
Lewis 101
Gregory Vieira
Department of Physics
Rhodes College
 
Thurs, Feb 6
Lewis 101
Yuan Li
Department of Astronomy
University of California — Berkeley
Supermassive Black Hole Feedback in the Centers of Massive Galaxies and Galaxy Clusters
Tue, Feb 11
Lewis 101
Phillip Cowperthwaite
Carnegie Observatory
Carnegie Institution for Science
 
Thurs, Feb 13
Lewis 101
Daniel D'Orazio
Institute for Theory and Computation
Harvard University
 
Tue, Feb 18
Lewis 101
Hsin-Yu Chen
Black Hole Initiative
Harvard University
 
Tue, Feb 25
Lewis 101
 
 
 
 
Tue, Mar 3
Lewis 101
 
 
 
 
Tue, Mar 10
Lewis 101
Spring Break
 
 
 
Tue, Mar 17
Lewis 101
 
 
 
 
Tue, Mar 24
Lewis 101
 
 
 
 
Tue, Mar 31
Lewis 101
 
 
 
 
Tue, Apr 7
Lewis 101
 
 
 
 
Tue, Apr 14
Lewis 101
 
 
 
 
Tue, Apr 21
Lewis 101
 
 
 
 
Tue, Apr 28
Lewis 101
 
 
 
 
Tue, May 5
Lewis 101
Final Exam Week  

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Abstracts of Talks


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.


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.


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.


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.