Colloquia / Seminars

Fall 2023

M, August 28th

From bioinspired structure formation to particle-based metamaterials

Andreas Fery Institut für Polymerforschung Dresden and Technical University Dresden, Germany

Metallic nanoparticles offer a number of interesting optical and electronic effects. A prominent example is localized surface plasmon resonance (LSPR), which is due to resonance excitations of the free electron cloud vibrations of the particles by light. Due to LSPR, plasmonic nanoparticles provide excellent opportunities for controlling electromagnetic near-fields at optical frequencies, which has led to a wide range of applications in various fields such as surface-enhanced spectroscopy, light harvesting, or photonics.

While much of the research has been devoted to understanding nanoparticle synthesis and tailoring their LSPR at the single-particle level [1-3], the ordering of particles at different length scales opens another powerful route to optical and electronic functionality due to novel collective plasmonic excitations arising from plasmonic coupling effects.

We focus on achieving such ordered particle arrays through assembly approaches. Colloidal self-assembly can indeed achieve well-defined colloidal clusters [4] and surface arrays [5] where coupling effects can be controlled. In particular, large-scale assemblies are possible in combination with biomimetic surface patterning. We discuss the underlying physicochemical principles of the assembly process and the resulting plasmonic coupling effects [6,7]. Finally, we present perspectives on how this assembly principle can be applied to metasurfaces with high field enhancement and/or ultrahigh circular dichroism

 

M, Sept 4th no class

M, Sept 11

Probing the Early Universe with Dark Matter Annihilation

Adrienne Erickcek, University of North Carolina
Observations of the oldest light in the Universe and other astronomical measurements indicate that only 5% of the current energy content of the Universe is stored in elements found on the periodic table. The other 95% is composed of dark matter and dark energy: dark matter is responsible for the growth of galaxies, while dark energy shoves galaxies apart at an accelerating rate. I will summarize the observational evidence for dark matter and dark energy, including how we infer that all galaxies are surrounded by vast halos of dark matter. These halos are thought to have formed through the mergers of smaller clumps of dark matter. As remnants of the earliest stages of structure formation, the smallest dark matter halos provide a unique probe of the expansion history prior to Big Bang nucleosynthesis. I will discuss how the evolution of the early Universe can enhance the microhalo population, thereby boosting the dark matter annihilation rate if dark matter is generated by pair production. The amplitude of this boost is highly sensitive to the size of the smallest halos, which provides an additional window into the dynamics and particle content of the early Universe. It is therefore possible to use astronomical observations to learn about the origins of dark matter and the evolution of the Universe during its first second.

M, Sept 18th

Ab Defects in Perovskites- a Key Differentiator from other Semiconductors

Jinsong Huang Department of Applied Physical Science, UNC-CH
Electronic defects within the band gap of semiconductor materials play critical roles in determining the efficiency and stability of their photovoltaic devices. Eliminating deleterious defects in semiconductors or passivating them during the fabrication process of solar cells has become one of the most fundamental tasks for the solar cell community. This scenario is also prevailing in the metal halide perovskite solar cell community which has witnessed a rapid increase of the power conversion efficiency of perovskite solar cells from 3.8% to over 26% with overwhelming reported progress on defect passivation strategies which also enhance the stability of perovskite solar cells. Any further improvement of the efficiency or stability of perovskite solar cells toward their Shockley-Queisser limitations have to rely on deeper understandings on the nature of defects in perovskite to squeeze out all non-radiative charge recombination paths by eliminating or passivating them.
Here I will present several studies of defects in perovskites, including both deep ones and shallow ones. I will show how we find out the density of defects, distribution, chemical nature, etc, of deep trapping defects. I will also report our recent discovery of unique properties of shallow defects in perovskites which enable perovskites to be much more defect tolerant.

M, Sept 25 Well Being Day- no class

M, Oct 2

Hybrid Perovskite Spintronics

Dali Sun, NCSU
Researchers have shown that hybrid organic-inorganic perovskites (or organometal trihalide perovskites) are not only aimed to be used in solar cell applications but also pursue a vast variety of fundamental research directions. One of the growing topics is the understanding of photo-physics and spin-related properties in hybrid perovskites since they play a major role in the processes of carrier photogeneration and carrier transport, which are the corner stone’s of photovoltaic applications, as well as in other optoelectronic applications. In this talk, we will discuss the spin-optoelectronic and magnetic properties of these solution-processed hybrid materials and their fundamental spin-dependent physical behavior: (i) We will talk about the observation of spintronic-Terahertz (THz) radiation in layered Pb-based hybrid perovskites interfaced with a ferromagnetic metal, produced by ultrafast spin current under femtosecond laser excitation. Due to the presence of the pronounced Rashba splitting state in Pb-based hybrid perovskites, the generated THz radiation exhibits an asymmetric intensity toward forward and backward emission direction whose directionality can be mutually controlled by the direction of the applied magnetic field and linear polarization of the laser pulse. (ii) We will show that the Dzyaloshinskii–Moriya-Interaction (DMI), a chiral antisymmetric interaction that occurs in magnetic systems with low symmetry, can be presented in layered magnetic hybrid perovskites of which the metal site, Pb is replaced by Cu. We show that layered Cu-based hybrid perovskite antiferromagnets with an interlayer DMI will lead to a strong intrinsic magnon-magnon coupling strength up to 0.24 GHz, which is four times greater than the dissipation rates of the acoustic/optical magnonic modes. Our work shows that the DMI in these hybrid antiferromagnets holds promise for leveraging magnon-magnon coupling by harnessing symmetry breaking in a highly tunable, solution-processable layered magnetic platform.

M, OCT 9th

TBA

Dr. Galen Reeves, Duke
TBA

M, Oct 16th

Diffuse Optics for Noninvasive Hemodynamic Monitoring of Bone, Brain, and Breast

Regina Choe, University of Rochester

Diffuse optics is an optical technique that can non-invasively probe hemodynamic parameters of deep tissue using light sources in the near-infrared spectral window (650 – 950 nm). With diffuse optical spectroscopy and tomography technique, the photon propagation model based on diffusion equation enables one to decouple the absorption and scattering, thus quantify oxygenated hemoglobin, deoxygenated hemoglobin, water and lipid concentrations. Blood flow can be quantified by measuring the temporal intensity autocorrelation function of diffusing light with diffuse correlation spectroscopy and tomography technique. These intrinsic physiological parameters have great potential to assess therapeutic efficacy of various treatments. In addition, the use of non-ionizing radiation and technologically simple, fast, inexpensive instrumentation makes diffuse optics attractive for translational research.

In this presentation, theoretical background and instrumentation of these techniques will be introduced. Afterwards, the potential utility of diffuse optics will be demonstrated through three different applications. First, we will show the possibility of utilizing early longitudinal changes in blood flow and total hemoglobin concentration to predict the quality of healing after bone injuries in a murine injury model. Second, we will introduce our approach to detect brain injury in patients undergoing extracorporeal membrane oxygenation treatment using non-invasive multi-modal brain monitoring. Lastly, we will demonstrate the potential to predict treatment efficacy for breast cancer chemotherapy based on temporal hemodynamic changes.

M, Oct 23rd

NANOGrav: The Dawn of Galaxy-scale Gravitational Wave Astronomy

Steve Taylor, Vanderbilt University
For more than 15 years, NANOGrav and other pulsar-timing array collaborations have been carefully monitoring networks of pulsars across the Milky Way. The goal was to find a tell-tale correlation signature amid the data from all those pulsars that would signal the presence of an all-sky background of nanohertz-frequency gravitational waves, washing through the Galaxy. At the end of June this year, NANOGrav finally announced its evidence for this gravitational-wave background, along with a series of studies that interpreted this signal as either originating from a population of supermassive black-hole binary systems, or as relics from cosmological processes in the early Universe. I will describe NANOGrav’s journey up to this point, what led to the ultimate breakthrough, how this affects our knowledge of supermassive black holes and the early Universe, and what lies next for gravitational-wave astronomy at nanohertz frequencies.

M, Oct 30th

My Journey from Physics to Finance

Dave Phillips, Truist Bank
Physicists that pursue a career in finance have often been referred to as “quants” due to their background and successful track record for
solving difficult quantitative problems in the industry. Although quantitative problem solving is a highly-valued skill, physics graduates offer a
diverse array of additional skills that are beneficial to a career in finance. In this talk, I will highlight how the skills and experiences acquired
as an experimental physicist have served as significant value-adds and helped facilitate a successful career in finance with
long-lasting impacts. To conclude, I discuss approaches for enabling a meaningful and impactful career journey in finance.

M, Nov 6th

(Machine) Learning of Dark Matter

Lina Necib, MIT 
In this talk, I explore the impact of stellar kinematics on understanding the particle nature of Dark Matter, overviewing the correlations between stellar and Dark Matter phase space distributions in four separate locations: the solar neighborhood, the Galactic center, dwarf galaxies, and streams. I will then focus on the use of machine learning techniques applied to data from the Gaia mission to disentangle the local kinematics substructures, and the use of simulations to study the correlations between stars and Dark Matter. I will end by relating these empirical measurements to Dark Matter detection experiments.

M, Nov 13th

Steve Elliott
Los Alamos National Laboratory

The Gallium Anomaly and the BEST Experiment

At the end of the last century, large volumes of gallium metal were used as targets to detect electron neutrinos (e) from the Sun. A small number of 71Ge atoms, produced in many tons of gallium through the charged current reaction 71Ga(e,e-)71Ge, were subsequently counted to determine the solar neutrino flux. 71Ge atoms are radioactive and their decays were observed in small proportional counters. The radiochemical technique procedures were extensively studied through auxiliary measurements, and tests with strong radioactive sources were performed. These source tests, however, found fewer 71Ge atoms than expected given the cross section and measured efficiencies. This, as yet unexplained result, is commonly referred to as the gallium anomaly.

The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate this anomaly, which has been frequently interpreted as evidence for oscillations between e and sterile neutrino (s) states. The BEST measurement consisted of a 3.414-MCi 51Cr e source placed at the center of two nested Ga volumes and measurements made of the 71Ge production at two different average distances. The measured rates in both volumes were low and hence consistent with oscillations. However, the rates in the two volumes were similar providing for other interpretations. This talk will summarize the history of the measurements, the BEST experiment and its results, the motivating physics, and possible interpretations.

M, Nov 20th

Quantum Information meets Quantum Matter

Lex Kemper, NCSU
Quantum computing has the potential to help us overcome the barriers that are presented by the end of Moore’s law. In the natural sciences, these barriers appear as limitations in computer memory and/or processing speed which prevent scientists from describing the problem fully and forcing them to work on smaller models or with approximate methods. Since nature is fundamentally quantum, it is quite natural to view a quantum computer as a bespoke quantum simulator, where we can examine the open problems in science at a scale not possible with classical computers. In this talk, I will present how this is achieved, and discuss some of our recent work in this area. I will outline how bringing the perspective of a condensed matter physicist into the realm of quantum information can help make quantum algorithms for simulation of many-body physics better, and even usable on today’s quantum computers.

M, Nov 27th

Title: Locality, Symmetry, and Coherence Through the Lens of Quantum Information

Iman Marvian, Duke
The primary goal of quantum information science is to harness the power of quantum systems for computing and information processing tasks. Interestingly, it turns out that the quantum information point of view also provides new insights and raises new questions about the fundamental concepts of locality, symmetry, and coherence. In the first part of my talk, I will discuss an ongoing project focused on understanding the implications of symmetries and locality of interactions within the framework of quantum circuits. For example, I will explain how a recent surprising no-go theorem in this context has led us to devise new types of experiments to probe the locality of interactions. I will also discuss novel methods for synthesizing energy-conserving quantum circuits with XY interaction and explore their applications for suppressing noise in quantum computers. In the second part of my talk, I will briefly discuss another ongoing project concerning the role of coherence in quantum thermodynamics.

M, Dec 4th

From Cleanroom to Boardroom: Applying Physics and Materials Science Insights for Strategic Business Decisions

Dr. Rudresh Ghosh- Global Director for Technology Sales and Commercialization at PulseForge, Inc.

In this talk, I’ll take the audience through the twists and turns of my professional journey—starting from navigating the world of physics grad school to leading a business team in the electronic and semiconductor manufacturing space. We’ll kick things off with a quick dive into my academic research acivities at UNC and how they connect with my technical experiences at PulseForge. I’ll share insights into how my technical know-how paved the way for technical leadership roles and, eventually, broader strategic leadership responsibilities within my organization. I’ll give the audience a glimpse into what a “regular” day for somebody in a technical sales and commercialization role looks like. As we wrap up, I’ll shed light on how grad school acted as a launchpad for my current role, sprinkled with a few things I wish I knew back then.

Spring 2024

W, Jan 10

Expanding the horizon of Renormalization group in quantum matter

Han Ma- University of Waterloo

Renormalization group (RG), originally proposed by Wilson, is a cornerstone in physics. While the Wilsonian RG was proved to be a powerful tool for understanding many condensed matter phenomena, the modern research has discovered many interesting phases that may not be well captured by traditional RG method. In this talk, I will give a brief review about the application of RG in condensed matter physics. And then I will explain why it is insufficient in the modern era. Later, I will introduce our new RG framework applicable to metals, which leads to new discoveries testable experimentally.

W, Jan 17th

Robust ergodicity breaking in quantum dynamics from topology

Oliver Hart- University of Colorado
When do many-body quantum systems fail to reach thermal equilibrium under their own dynamics? Furthermore, just how robust can this ergodicity breaking be? These questions underpin the field of quantum dynamics and many physicists have wrestled with them during the past decade. In this talk I will present a recent breakthrough, which provides a route to obtaining ergodicity breaking with an unprecedented degree of robustness. By incorporating concepts from topological phases of matter into quantum dynamics, we arrive at a model that is robust to arbitrary (k-local) perturbations. I will provide an overview of how this development compares to more “traditional” ways to evade thermalization and discuss the rich phenomenology that models of topologically stable ergodicity breaking can exhibit.

M, Jan 22

Composite fermions and the zero-field fractional quantum Hall effect

Hart Goldman- University of Chicago

Among the greatest discoveries of 20th century physics was the fractional quantum Hall (FQH) effect in two dimensional semiconductor materials immersed in a strong magnetic field. Since their initial experimental observation, FQH phases have been understood to be quintessential topological phases of matter, exhibiting long ranged quantum entanglement and playing host to exotic, emergent excitations with electric charge and exchange statistics that are fractions of those of the electron.

Remarkable recent experiments have revealed evidence of the FQH effect in systems without any external magnetic field, in a growing number of two dimensional materials. In this colloquium, I will present a unified theoretical framework for understanding the emergence of zero-field FQH phases in terms of “composite fermions,” emergent particles that are combinations of electric charge and magnetic vortices. One central prediction of the composite fermion picture is the possibility of an “anomalous composite Fermi liquid” (ACFL) phase, which is a strongly interacting metal of composite fermions. I will describe theoretical and numerical evidence for this ACFL state, as well as its importance in the zero-field FQH phase diagram. I will also present the experimental implications of the ACFL and discuss the growing evidence for this phase in zero-field FQH materials. I will conclude by describing how these ideas can launch us into addressing the exciting new questions and research directions in this emerging field.

M, Jan 29

Optical Control of Quantum Magnetism

Jonathan Curtis- UCLA
New developments in intense infrared coherent light sources have enabled the generation of highly nonlinear dynamics in materials on ultrafast timescales, opening new avenues for the study and manipulation of quantum materials. Correlated magnetic insulators — materials in which the electronic charge is frozen but the spin still exhibits strong quantum fluctuations — often host a variety of interesting and potentially useful magnetic phases while also minimizing optical absorption, making them ideal
candidates for optical control. Here I will present two such examples of how intense radiation can be used to induce nonequilibrium dynamics in these materials.
First, I will consider the multi-orbital Mott insulator YTiO3, which hosts fluctuating ferromagnetic order within a quasi-degenerate orbital manifold. I will show how in the presence of strong terahertz radiation, the nonequilibrium magnon dynamics in this system can be dramatically different from equilibrium due to the presence of the multiple orbital states. In particular, by utilizing this orbital degeneracy, it is possible to tune the magnon lifetime over an order of magnitude, allowing one to control the speed of
magnetization dynamics. Second, I will consider the insulating cuprate compound Sr2Cu3O4Cl2 (2342) which hosts two-dimensional spin-½ Neel order. Upon intense optical driving, ultrafast melting of the Neel order is observed, with a dramatic resonant absorption occurring when the photon energy is twice the energy of a Van Hove singularity in the magnon spectrum. I will show how this “bimagnon” absorption can be
understood as parametric driving of the spins by the optical electric field. This mechanism potentially paves the way for optical generation of entangled magnon pairs, and is particularly interesting given the relationship between spin fluctuations and high-temperature superconductivity seen in cuprates.

W, Jan 31st

Quantum adventures out of equilibrium: new topological order and the fate of many body localization

Philip Crowley- Harvard

Major breakthroughs in 20th century condensed matter were made by understanding how quantum mechanical effects emerge in equilibrium systems, in particular in naturally occurring materials in the world around us.

Recent technological developments in cold atoms & molecules, and superconducting qubits have given us experimental access to tunable and controllable synthetic quantum systems which are colder, cleaner, and with longer coherence times than those found in nature. This has provided the ability to observe non-equilibrium quantum dynamics in action. Consequently, a new landscape of possibilities for non-equilibrium quantum order has been opened

I will survey some recent theoretical developments in uncovering robust new quantum phenomena in quantum systems, and their realization in experiments. In particular, I will focus on significant recent developments regarding (i) systems which have been observed to violate one of the foundational axioms of statistical mechanics, ergodicity, and “many-body localize”, and (ii) new robust forms of driven topological order. These serve as two examples in a growing body of knowledge of non-equilibrium quantum phenomena. Finally, I comment on new directions in synthetic quantum systems and synthetic quantum materials.

M, Feb 5th

Precision Binary Black Hole Waveform Modeling: Foundations and Recent Advances

Leo Stein-University of Mississippi at Oxford
Binary black hole mergers are the dominant gravitational-wave sources that LIGO/Virgo/KAGRA detect. For detection, parameter estimation, and tests of GR, we need waveform models from numerical relativity and analytical theory. I will give an overview of how to calculate these waveforms, then delve into recent advances. Future ground- and space-based GW detectors demand higher precision and require us to capture more subtle effects, such as gravitational-wave memory and nonlinear ringdown. These advances pave the way toward the precision gravitational-waveform era.

W, Feb 7th

Shedding Light on Topology: Exploring Topological Materials with Light-Matter Interactions

Junyeong Ahn- Harvard
Exploration of topological materials is a central theme of modern quantum condensed matter physics, and it is currently encountering new horizons. Traditionally, the field has focused on static and DC-transport properties, based on the understanding that topological phases are defined by ground-state properties. However, this talk will spotlight an emerging topic: the dynamic properties of topological materials. Through studying light-matter interactions, I will demonstrate how we can use dynamic properties to shed light on the topological properties of materials and bridge these to broader quantum phenomena. In particular, I will highlight intriguing optical phenomena in topological magnets and superconductors.

W, Feb 14th

The Eccentric Behavior of Compact Binaries

Dr. Nicholas Loutrel, Milan-Bicocca

The exceptional efforts of the LVK collaboration have resulted in the unprecedented detection of gravitational waves from ninety compact object binaries, most of which are binary black holes. Recent reanalysis of the current catalog has revealed that some of the sources may be consistent with binaries possessing small orbital eccentricity, while one is speculated to be formed from a highly eccentric merger. Such results have led to a renewed interest in the effect of orbital eccentricity on gravitational waves emitted by binary systems, and what can be inferred from its presence. In this talk, I will present a broad overview of gravitational wave generation and the effect orbital eccentricity has on this, the current state of our eccentric waveform models and where improvement need to be made, and why eccentricity is important for extracting fundamental physics and astrophysics from gravitational waves.

W, Feb 21st

Asymptotic Symmetries in Gravity: history, developments and applications to GW theory

Dr. Roberto Oliveri- Observatoire de Paris, Meudon

Asymptotic symmetries play a crucial role in gravity, particularly in understanding the behaviour of gravitational systems at large distances. The relevance of asymptotic symmetries has always been central in the quest for the holographic nature of gravity. Recently, this relevance has expanded towards topics in connection with gravitational-wave detections. Asymptotic symmetries improve the accuracy of gravitational waveforms, give an elegant explanation of memory effects, and control scattering amplitude in the infrared regime. I will summarize the fascinating history that led to asymptotic symmetries in gravity, provide a physical intuition of these symmetries, and describe their relevance for gravitational-wave physics.

W, March 20th

Probing the Extremes of Stellar Evolution in the Decade of 20 Million Transients

Griffin Hosseinzadeh- University of Colorado

In the decade from 2025-2035, we expect to discover several tens of millions of astronomical transients, thanks to Vera C. Rubin Observatory and the International Gravitational-Wave Observatory Network. This presents both an enormous opportunity, in that previously rare classes of transients will soon be discovered routinely, but also a wake-up call that traditional techniques of classification and analysis are not cut out for the job. In this colloquium, I will describe the current and future landscape of transient astronomy: the aspects of stellar physics we can constrain using large samples of stellar explosions, as well as the data science methods our field must adopt in order to take full advantage of our observations. For example, initial samples of tens of core-collapse supernovae have provided surprising clues about extreme mass loss and pre-explosion eruptions in massive stars. Similarly sized samples of thermonuclear supernovae observed within days of explosion show unexpected behavior that could provide hints about their poorly understood progenitor systems and explosion mechanisms. Lastly, a single gravitational-wave-triggered kilonova suggests that these events may dominate the production of the heaviest elements in the Universe, but we have almost no information about diversity within that class. In all these cases, modern cyberinfrastructure (e.g., real-time discovery alerts, robotic follow-up observations, robust image subtraction, machine-learning classification) will be key to maximizing the science return from powerful new discovery engines.

W, March 27th

Insights Into Stellar Evolution and Beyond from Hot Subluminous Stars

Brad Barlow- High Point

Over the past ten years, the European Space Agency’s Gaia mission has uncovered nearly 100,000 stars located between the tip of the white dwarf cooling sequence and main sequence in the H-R diagram. Collectively referred to as hot subluminous stars, several types of objects have evolutionary tracks passing through or near this location, including pre-extremely low mass white dwarfs, core He-fusing hot subdwarf stars, post-blue horizontal branch stars, cataclysmic variables, subdwarf A stars, and more. Some neutron star spider binaries can even exhibit similar colors and luminosities due to the effects of irradiation on their cool companions. Essentially all hot subluminous stars share one common trait: binary interactions are necessary for their formation. Here I will present several research projects that leverage this fact to gain insights into stellar evolution, Roche lobe overflow processes, common envelope ejection, and other interesting astrophysical phenomena. The broader impacts of this work touch on gravitational wave physics, Type 1a supernovae, the impact of late-stage stellar evolution on exoplanets, and more. I will end by briefly discussing plans for developing low-cost, low-resolution spectrographs to assist in these studies and follow-up observations of transients generated by Argus, LSST, and other photometric surveys.

M, April 1st

Life on an Endless Hill: Making Sense of Up-Side-Down
Potentials in Quantum Mechanics and High Energy Physics

Paul Romatschke- University of Colorado

In classical physics, unbounded (or “up-side-down”) potentials do not allow for a stable ground state. As a consequence, unbounded potentials have often been dismissed as not viable for proper unitary quantum theories. Historically, we have learned that the quantum world often contradicts dearly held beliefs based on classical physics. By contrast, mathematics has been recognized as a good guide even when classical intuition fails. In this talk, I will use well-developed mathematics to explore physical systems with up-side-down and non-Hermitian potentials in quantum mechanics and
quantum field theory, finding that — contrary to widely held and endlessly repeated beliefs — these systems often do in fact possess a stable ground state in the quantum world. This realization challenges statements that have become pillars of high energy physics, such as the quantum triviality of the Higgs field and reserving asymptotic
freedom only for non-Abelian gauge theories. It’s a revolution in the making, so please join me for a “sneak-preview” of what’s coming.

W, April 3rd

Mapping Ultra-Low Surface Brightness Emission Around Nearby Galaxies: The Alliance of UV and Optical Instrumentation

Nicole Melso- University of Arizona

All of the undiscovered gas in the universe lies in the dimmest parts of the sky, in the intergalactic medium (IGM) and circumgalactic medium (CGM) beyond galaxies. This gas emits light below the detection threshold of most modern-day observations and is only visible to instruments with extremely low surface brightness sensitivity. This presentation will focus on the development of two instruments optimized to push the boundaries of wide-field, low-surface brightness spectral imaging. Aspera is a UV small satellite mission tailored to map low surface brightness OVI emission in the low-redshift universe. The Circumgalactic Ha Spectrograph (CHaS) is an optical integral field unit (IFU) spectrograph on Kitt Peak designed to detect diffuse ionized gas around nearby galaxies. Both of these spectrographs are powerful survey instruments, leveraging a large light gathering power (grasp) to compete with much larger aperture instruments. The paring of optical and UV instrumentation is key to uncovering the faint reservoir of gas around galaxies including: the fuel for future star formation, the remnants of past galaxy mergers, and the large-scale structure of the universe. I will debut the discovery of a new extended emission line region around NGC 1068 and highlight advances in ultra-low surface brightness spectroscopy – including the development of future instruments for SOAR – that will continue to uncover similarly faint, far-flung gas in the local universe.

W, April 3rd

Near-Field Cosmology with wide-field surveys of resolved galaxies

Denija Crnojevic-University of Tampa

The widely accepted Lambda Cold Dark Matter cosmological paradigm faces important challenges at the scales of individual galaxies, primarily linked to the implementation of baryonic physics in cosmological simulations. The study of resolved stellar populations in the nearest galaxies, or “near-field cosmology”, provides key constraints on the physics underlying galaxy formation and evolution. In this talk, I will present ongoing panoramic imaging surveys of galaxies in the Local Volume, performed with ground-based wide-field imagers and extensively followed-up with a multiwavelength approach. Such surveys constitute the first accurate characterization of the past and ongoing accretion processes shaping the halos of these nearby galaxies and their satellite populations: they do not only quantitatively inform theoretical models of galaxy formation and evolution, but also represent a necessary testbed in preparation for the next generation of ground-based and space-borne telescopes (JWST, VRO, Roman, TMT).

M, April 15th

Investigating and supporting student reasoning in physics:
The role of dual-process theories of reasoning

MacKenzie R. Stetzer- University of Maine

For over 30 years, research-based materials developed by the physics education research community have helped transform introductory physics instruction. Many of these materials focus on the development of student conceptual understanding and place considerable emphasis on qualitative inferential reasoning. An emerging body of research, however, suggests that poor student performance on certain physics tasks – even after research-based instruction – may stem more from the nature of human reasoning itself than from specific conceptual difficulties. Analysis of student reasoning patterns through the lens of dual-process theories of reasoning (DPToR) from cognitive science suggests that students may struggle to engage analytical processing productively when responding to physics questions containing salient distracting features. As part of a multi-institutional effort to examine and support student reasoning in physics by leveraging DPToR, we have been developing novel methodologies to probe student reasoning more deeply (including, for example, reasoning chain construction tasks) and designing and testing DPToR-aligned interventions aimed at promoting productive and consistent reasoning. In this talk, results from this ongoing work will be presented and implications for instruction and research-based curriculum development will be discussed.

M, April 29th

Hunting for Neutrinos and Dark Radiation with Cosmic Datasets

Marilena Loverde- University of Washington

Neutrinos and other light particles can leave a number of imprints in the cosmic microwave background anisotropies and on maps of the large-scale structure of our Universe. These imprints can not only demonstrate the presence of these particles and constrain their masses, but can provide insight into their nature via signatures of interactions or other behavior that changes during the history of the Universe. I will describe this physics, present constraints on non-standard neutrino self-interactions and other forms of dark radiation from cosmic datasets. I will also discuss novel signatures of massive neutrinos and the new technology needed to model their impact on structures in the Universe today.