Abstract: In this talk I discuss recent and ongoing work to understand the end of inflation and the nature of dark matter. I will start by discussing simulations of nonlinear structure formation during post-inflation reheating. I will then show how this early phase of the universe is analogous to axion-like dark matter. I will finish by discussing two lines of ongoing work with axion-like dark matter. First, using strong gravitational lensing to constrain ultralight dark matter. Second, developing new simulations of two-axion models.
Colloquium
Friday, October 15, 2021 - 3:10pm to 4:00pm
· Colloquium
Dr. Nathan Musoke
Friday, October 8, 2021 - 3:10pm to 4:00pm
· Colloquium
Prof. Chanda Prescod-Weinstein
Abstract: In this talk, I discuss ongoing efforts to understand axion and axion-like particle (ALP) dark matter and how we may use neutron stars to characterize other types of dark matter. I focus in particular on self-interactions and how they shape astrophysical phenomena in ALP scenarios. I will discuss work that shows that the self-interaction should not be ignored and that the sign of the interaction makes a significant difference in the evolution of the system, both for QCD axions and fuzzy dark matter.
Friday, September 17, 2021 - 3:10pm to 4:15pm
· Colloquium
Prof. Jeffrey Oishi, Bates College
Fluid physics, including hydrodynamic and magnetohydrodynamic flows, is of crucial importance in numerous geophysical and astrophysical contexts from turbulent mixing of ocean waters to the dynamo generation of Solar and planetary magnetic fields. These processes are inherently multi-scale, strongly non-linear, and far from equilibrium. Many important problems are anisotropic due to the interplay between convection, rotation, and magnetic fields. As a result, highly turbulent flows drive large-scale patterns: jets, mean magnetic fields, and transport barriers.
Friday, April 30, 2021 - 3:00pm to 4:00pm
· Colloquium
Dr. Chigomezyo Ngwira, Atmospheric and Space Technology Research Associates, Louisville, CO, USA
Disturbances from the Sun often referred to as “space weather”, cause geomagnetic storms that can affect critical infrastructure on the ground such as navigation systems, high-voltage electric power transmission grids, and pipelines. Understanding the dynamic response of the coupled solar wind-magnetosphere-ionosphere system to severe space weather is an on-going challenge. This talk will highlight some of my past and on-going applied space weather research efforts and how this information can be used to address societal needs.
Friday, April 23, 2021 - 3:00pm to 4:00pm
· Colloquium
John Clem, Bartol Research Institute, Department of Physics and Astronomy, University of Delaware
A new measurement of the Cosmic Ray Electron and Positron spectra in the energy range of 20 MeV–1 GeV will be presented. The data were taken during the first flight of the balloon-borne spectrometer Anti Electron Sub-Orbital Payload (AESOP-Lite), which was flown from Esrange, Sweden, to Ellesmere Island, Canada, in May 2018. The payload collected over 130hrs of exposure at an average altitude of 3g/cm^2. The instrument incorporates a gas Cerenkov detector and a magnetic spectrometer to identify particle type and measure the energy.
Friday, April 2, 2021 - 3:00pm to 4:00pm
· Colloquium
Dr. Ilaria Caiazzo, Burke Prize Fellow at the California Institute of Technology
After five decades since the first detection of X-ray polarization from the Crab, we only have a handful of measurements of X-ray polarization from astronomical objects. In recent years, a few small missions, like X-Calibur and PolarLight, have started to increase the pool of observations, pioneering new technologies that will be implemented in larger observatories. This year will mark the start of routine polarization observations of X-ray sources, with the launch of a dedicated mission: IXPE.
Friday, February 12, 2021 - 3:10pm
· Colloquium
Victor Yakovenko, Professor of Physics at the University of Maryland
Abstract: Inequality is an important and seemingly inevitable aspect of the human society. Various manifestations of inequality can be derived from the concept of entropy in statistical physics. In a stylized model of monetary economy, with a constrained money supply implicitly reflecting constrained resources, the probability distribution of money among the agents converges to the exponential Boltzmann-Gibbs law due to entropy maximization. Our empirical data analysis shows that income distributions in the USA, European Union, and other countries exhibit a well-defined two-class structu