The Physics and Astronomy Colloquium Series is hosted on most Wednesdays from 2:30pm to 3:20pm in White Hall G09 on the WVU Downtown Campus. A reception precedes each colloquium in White Hall, Room 111 at 2:00 PM. If you have any questions about the Physics and Astronomy Colloquium Series, please contact the P&A Colloquium Committee Chair (Prof. Giulia Murtas) or Miranda Heitz.
 

• September 9: Department Research Group Showcase
  • Presenters: Professor Loren Anderson (Astronomy and Astrophysics), Professor Micky Holcomb (Condensed Matter Physics), Professor John Stewart (Physics Education Research), and Professor Earl Scime (Plasma and Space Physics)
     
• September 23: Giuseppe Arro, "Nonthermal particle accelearation by magnetic pumping in pulsating plasmas" (Plasma - University of Wisconsin, Madison)
  • Abstract: The origin of high-energy particles in astrophysical sources is still debated, especially in high-beta plasmas, where magnetic energy is insufficient to cause nonthermal particle acceleration. However, high-beta plasmas are often embedded in large-scale compressible flows that could accelerate particles via magnetic pumping (MP), a mechanism where the plasma is energized by instabilities driven through cyclic compression and expansion (pulsation). In this work, we investigate particle acceleration by MP in high-beta "pulsating" plasmas, using fully kinetic simulations implementing a new "pulsating box" setup, showing for the first time that MP efficiently accelerates particles, producing nonthermal distributions with high-energy power-law tails. To interpret our results, we formulate a new generalized maximum entropy (GME) principle, extending the thermodynamic concept of maximum entropy to non-equilibrium plasmas. Numerical results are in excellent agreement with our model, accurately describing the evolution of the power-law index of distributions as a function of the injected energy. Our results are relevant for understanding particle acceleration in high-beta astrophysical plasmas, including planetary magnetosheaths, the intracluster medium of galaxy clusters, and accretion disks of compact objects.
     
• September 30: Joe Lazio (Astronomy - NASA Jet Propulsion Laboratory)
  • Abstract: The Sun Radio Interferometer Space Experiment (SunRISE) is a NASA Mission of Opportunity designed to reveal aspects of how solar energetic particles (SEPs) are accelerated at coronal mass ejections (CMEs) and how they propagate in interplanetary space. SunRISE is a constellation of six identical small spacecraft (6U CubeSats) that will form a space-based radio telescope.  Each spacecraft carries a payload designed to receive simultaneously signals from solar radio bursts and global navigation satellite system (GNSS) satellites.  By tracking the locations of solar radio bursts over time, SunRISE will address enduring questions in space plasma physics, some dating back to the early days of radio astronomy, regarding the acceleration and transport of SEPs. The six spacecraft that form the SunRISE radio telescope will fly in a passive formation in a supersynchronous geosynchronous Earth orbit (super-GEO).  The nominal separation between spacecraft will be 10 km, obtaining an angular resolution of approximately 10 arcminutes at 10 MHz.  I describe the implementation of SunRISE, illustrating how the combination of on-board and ground operations and processing are required to achieve a space radio telescope. While SunRISE will conduct science in its own right, it also is intended to be a pathfinder for future space-based radio astronomy missions.  I provide an initial assessment of the "experience gained" for future missions, from the perspective of both the SunRISE science and technical implementation.
  • Biography: Joseph Lazio is a research scientist at the University of Michigan.  He earned his Ph.D. at Cornell University, then held a National Research Council Fellowship at the U.S. Naval Research Laboratory (NRL).  He has been a radio astronomer on the staff of the NRL and Principal Scientist at the Jet Propulsion Laboratory (JPL), California Institute of Technology.  He has been a key participant in the design and development of radio telescopes including the Low Frequency Array (LOFAR), the Long Wavelength Array (LWA), and the Square Kilometre Array (SKA), serving as the Project Scientist for the latter.  Most recently, he has been Project Scientist for NASA's Deep Space Network (DSN) and for the Sun Radio Interferometer Space Experiment (SunRISE).  He was named a Fellow in the American Association for the Advancement of Science (AAAS) for his role in advancing radio astronomy telescopes and providing scientific guidance to the DSN.

• October 7: Jyoti Katoch (Condensed Matter Physics - Carnegie Mellon University)
  • Abstract: Van der Waals (vdW) heterostructures offer an unprecedented platform for engineering the physical properties of two-dimensional (2D) materials through control of twist angle, strain, and interactions. The advent of state-of-the-art angle-resolved photoemission spectroscopy with nanoscale spatial resolution (nanoARPES), combined with its ability to probe fully functional devices, has opened new avenues for directly visualizing exotic electronic phenomena in these systems. In this talk, I will present our work leveraging cutting-edge in-operando nanoARPES to directly map the electronic properties of vdW heterostructures and their functional devices. I will highlight experiments that demonstrate on-demand tuning of the electronic structure by varying the substrate, twist angle, alkali metal doping, and applying an electric field. 
  • Biography: Jyoti Katoch received her Ph.D. in Physics from the University of Central Florida. She then worked as a postdoctoral researcher and later as a research scientist at The Ohio State University. She joined the Department of Physics at Carnegie Mellon University in 2018 and currently an Associate Professor. She is a recipient of the Ralph E. Powe Junior Faculty Enhancement Award, 
    Department of Energy Early Career Award, and National Science Foundation Early Career Award.  She has held multiple leadership roles, including Chair of the Conference for Undergraduate Women in Physics at CMU, Chair of the 2D Technical Group of the American Vacuum Society (AVS) from 2023–2024, and currently serves as a member of the AVS Executive Committee. 

• October 21: Nehpreet K. Walia, "From solar wind to the boundary of our heliosphere" (Plasma - Princeton University)
  • Abstract: This talk explores dynamic heliospheric processes and particle acceleration mechanisms from close to the Sun to the boundary of our heliosphere. First, we examine how successive 2012 and 2013 coronal mass ejections enhanced the pressure of the boundary of our heliosphere. These changes are measured using energetic neutral atom (ENA) emissions that are detected by NASA’s Interstellar Boundary Explorer (IBEX). These observations provide the direct link between solar wind changes and global heliospheric boundary dynamics. Second, we investigate nonthermal particle acceleration during asymmetric magnetic reconnection, a phenomenon relevant to recent Parker Solar Probe observations of the solar wind. Using kinetic simulations, we demonstrate that upstream density and magnetic field asymmetries reduce outflow speeds and yield softer energy spectra. The softer spectra result from the weaker acceleration caused by the misalignment between the magnetic curvature and the outflow jet in asymmetric reconnection. We propose a predictive theory relating initial asymmetries to the acceleration rate of particles, with broad implications for particle acceleration in the solar corona and Earth's magnetopause.
  • Biography: Nehpreet Walia is a postdoctoral researcher at Princeton University specializing in heliophysics. She is currently involved in NASA’s Interstellar Mapping and Acceleration Probe (IMAP), a flagship mission designed to characterize our heliosphere, the protective bubble that shields us from galactic cosmic rays. Before joining Princeton, Nehpreet was at Los Alamos National Laboratory, where she analyzed data from NASA’s Interstellar Boundary Explorer (IBEX) to investigate the impact of solar wind on the boundary of our heliosphere. She also performed high-performance computing (HPC) studies using Particle-In-Cell (PIC) and hybrid simulations to examine particle acceleration in solar wind. Nehpreet earned her Ph.D. in Space Physics from the University of Tokyo, Japan.  Her doctoral research combined data from NASA’s Magnetospheric Multiscale (MMS) mission with hybrid HPC simulations to understand the structure and geometry of magnetic reconnection.
     
• November 4: TBD
• November 18: TBD

• December 2: Stella Ocker, "Probing Cosmic Plasmas from Sub-AU to Gigaparsec Scales" (Astronomy - California Institute of Technology)
  • Abstract: Most of the ordinary matter in the universe takes the form of diffuse ionized gas, or plasma. Characterizing the full distribution of this plasma is critical to understanding how the universe forms its main structures. In this talk, I will discuss recent breakthroughs in our efforts to resolve the distribution of cosmic plasmas across a vast range of spatial scales, primarily based on observations of pulsars and fast radio bursts (FRBs). These observations are distinct in that they trace plasma densities on galactic and intergalactic scales, as well as sub-au plasma fluctuations. I will present the NE2025 Galactic electron density model, and demonstrate how an up-to-date understanding of the Milky Way’s turbulent ionized gas distribution will reveal extremely diffuse plasmas around and between galaxies, as well as enabling a sharp-eyed view of FRBs’ local environments. Implications for key surveys of the late 2020's, including the Schmidt Observatory System's Deep Synoptic Array, will be discussed.
  • Biography: "I am a Carnegie-Caltech Brinson postdoctoral fellow and received my Ph.D. from Cornell University. My research bridges the study of cosmic plasmas and compact objects using observations and empirical modeling. My main hobby of the past few years has been exploring the many facets of Los Angeles. You can learn more about me at my website: stellakochocker.com. "