Dr. Alec Tewsley-Booth

Postdoctoral Research Associate

Department of Physics and Astronomy

University of Kentucky

Host: Renee Fatemi and Tim Gorringe

Title: The Second Results from the Fermilab Muon g-2 Experiment

Abstract: On August 10th, 2023, the Muon g-2 Collaboration presented a new experimental value of the positive muon magnetic anomaly, a_μ = (g_μ - 2)/2. From this data set, the first analyzed since our release in 2021, we determine a_μ = 116592057(25) x 10^-11. This result dominates the new experimental world average, a_μ = 116592059(22) x 10^-11, which includes the 2021 result and the final result from Brookhaven in 2006. This talk will cover the experimental apparatus and analysis techniques used to produce the newest result, especially the improvements made that led to the factor of two improvement over the 2021 result. Additionally, we will cover the state of the theory and its tension with experiment, as well as the contributions from the University of Kentucky.

Yuanyuan Su

Assistant Professor

Department of Physics and Astronomy

University of Kentucky

Host: Gary Ferland and Tom Troland

Title: Studying galaxy clusters in multiwavelength, multiscale, and multidisciplinary

Abstract: As the largest gravitational bound systems in the Universe, galaxy clusters are one of the most important probes for testing the standard cosmological models. A typical galaxy cluster contains hundreds to thousands of member galaxies. The space between these galaxies is filled with hot and diffuse plasma -- the intracluster medium (ICM), which constitutes 90% of the baryonic mass and emits strongly in X-rays primarily through bremsstrahlung. ICM provides unique laboratories to study many astrophysical processes, such as the interaction between the hot baryons and the supermassive black hole, the growth of large scale structure, and the enrichment processes of the Universe. In this talk, I will present our recent discovery on galaxy clusters from its centers to the outskirts including the multiphase gas at the brightest cluster galaxies, bow shock in merging clusters, and the chemical composition of the ICM. Our work on active galactic nuclei in cluster member galaxies and machine learning applications will also be discussed. 

Prof. Susan Gardner

Department of Physics and Astronomy

University of Kentucky

Host: Brad Plaster

Title: QCD for New Physics Searches at the Sensitivity Frontier 

Abstract: 

Questions that drive searches for physics beyond the Standard Model  include the physical origin of the cosmic baryon asymmetry and of dark matter. Quark dynamics, as realized through the theory of quantum chromodynamics (QCD), can appear in these studies in very different ways. In this talk, I develop these possibilities explicitly, first describing the role of QCD in ultra-sensitive searches for new physics, particularly at low energies, and then turning to how its features could be exploited in describing the undiscovered universe, along with the essential observational and experimental tests that could confirm them.

The Arts & Sciences' Department of Physics and Astronomy invites local Hispanic and Latinx elementary school students from Cardinal Valley, Liberty and Maxwell elementary schools, to come explore outer space and learn about the amazing work that astronomers do! The celebration will include a fun-filled evening featuring activities, crafts, awesome speakers, and a chance to gaze into the beautiful night sky through our state-of-the-art space telescope housed inside UK's MacAdam Observatory. And to top it off, there will be free tacos, snacks and drinks! 

The gas-phase metallicity and ionization parameter are two primary parameters that drive the variations of emission line spectra in HII regions. There is an increasing amount of evidence that these two parameters are correlated. Theoretical works on the dynamical evolution of HII regions predict an anti-correlation between metallicity and ionization parameter. However, observations of HII region spectra have yielded a variety of different correlations, including anti-correlations, positive correlations, and even no correlation. All these measurements of the correlation rely on photoionization modeling. Also, different combinations of emission lines are used for calibrating metallicity and ionization parameter in different works. To solve the above problem, we examine how the derived correlation between metallicity and ionization parameter depends on the choice of models and emission lines. In this talk, I will show that it is important to constrain the model parameters using observational data before making any measurement. With the MaNGA IFU data, we compute a best-fit photoionization model for general HII regions and use a Bayesian method to fit metallicities and ionization parameters simultaneously. Our result shows that a positive correlation exists between the gas-phase metallicity and ionization parameter, regardless of which combination of emission lines is used for the fitting. This result clearly contradicts the prediction by the dynamical model. I will discuss potential mechanisms that lead to this discrepancy, and how it might be solved with future IFU surveys on HII regions.

Elements condensing into dust grains is an important physical process that occurs in the ISM. Through studies on extinction, scattering, heating and depletion of elements out of gas-phase, it has long been known that grains have a major effect on observed spectra of galaxies. Despite the large amount of observations available on extinction, scatter and heating, details of depletions onto grains and their effect on observed emission-line spectra are rarely studied. We explore the effects of grain depletions on strong spectral lines, and find non-trivial results. Our results suggest that the level of depletion, not only affects the emission line strength of corresponding ions, but also changes the abundance of coolants in the ISM gas, hence affecting its temperature. In addition, we include new code into Cloudy, allowing a user to alter the degree of grain depletions in a given model.

The environment in which a galaxy lives plays a key role in driving its evolution.  As the most tenuously bound component of galaxies, neutral atomic hydrogen (HI) is a valuable tracer of both the interaction history of a galaxy with its environment and a measure of its future star formation potential.  As galaxies move from the low-density field to high-density clusters, they lose their gas and star formation is quenched, but how exactly this happens is still poorly understood.  In fact, perhaps most galaxies spend a large fraction of their life in the intermediate-density group environment where the signatures of galaxy evolution are more subtle and widely varied.  In this talk I will present what my work on both wide-area HI surveys and individual observations have revealed about galaxy evolution, from the low mass group environment to the outskirts of massive galaxy clusters.  Statistical studies of the HI provide insight on not only the gas processing and ongoing evolution within galaxy groups, but also the growth of large-scale structure.  In addition, I'll present the first of the next generation of HI surveys, Apertif, which is observing 3500 square degrees at 14 times the spatial resolution of previous HI surveys and better HI mass sensitivity. Apertif will allows us to resolve and take the inventory, for the first time, of the physical mechanisms that remove gas from galaxies, across the full range of galaxy environments from poor groups to galaxy clusters.

Zoom Recording: https://uky.zoom.us/rec/share/HyMikMEOik6ZtjHliTbYeOx5-W5k-lH5hemITZcVBqec-w1Tu3rQOD6biC3qSb38.sPUbAc39PoZWKBwu