10/1Graduate Student Seminar
Graduate Student SeminarFriday, October 1st, 202112:15 PM - 01:15 PMStorrs CampusGS-119
The Cycle of Gas and Stars in Galaxies
There exists a “life cycle” of baryonic matter within galaxies between stars and the gas from which they formed. Dense gas clouds coalesce from the diffuse interstellar medium then collapse locally under the influence of gravity into star clusters. The most massive stars emit copious amounts of ultraviolet radiation during their short lifetimes, ionizing and disrupting their natal clouds, culminating in supernovae that inject energy, momentum, and heavy elements back into the bulk interstellar medium, where the cycle starts anew. The locations and rates of these various stages in the baryonic life cycle greatly impact the dynamical and chemical evolution of galaxies, and yet the details are still poorly understood outside our home galaxy. New observational facilities are now for the first time providing data of sufficiently high resolution to study the individual clouds in which stars are born across the full extent of other galaxies, shedding light on the key similarities and differences in the matter cycle across the local Universe. I will highlight recent results from three large observing campaigns of nearby galaxies of which my group is a part, which includes submillimeter, optical, and ultraviolet programs targeting newly formed stars and dense and ionized gas. Among a number of interesting conclusions, we are discovering that while most dense clouds appear to be near virial equilibrium and thus capable of forming stars, their environments clearly regulate the local baryonic cycle.
Astronomy SeminarWednesday, October 6th, 202102:00 PM - 03:00 PMStorrs CampusGS-119
Jasmine Ramirez: “Comprehending How Alkali Opacities Affect Brown Dwarf Spectra”
Niranjan Roy: “Simulating Star-Death: Hydrodynamical Simulations of Type La Supernovae”
Josiah Walker: “Using Neural Networks to Predict Momentum"
Meeting URL: https://uconn-cmr.webex.com/meet/cab16109
10/8Graduate Student Seminar
Graduate Student SeminarFriday, October 8th, 202112:15 PM - 01:15 PMStorrs CampusGS-119
Functional and Multiferroic Materials
In this talk, some of the basic properties of ferroics and multiferroics, and their applications in many devices will be discussed. Functional materials, such as ferroic materials have been grouped by the driving field that aligns their ordering parameters. Four primary ferroic materials: ferroelectric, ferromagnetic, ferroelastic, and ferrotoroidic, are characterized by a wealth of intriguing physical properties. The entire class of ferroic materials has found extensive applications in consumer electronics, a variety of sensors, memory devices, health care, and military applications. Current trends toward device miniaturization have led to an increased interest in multifunctionality, multifunctional devices, and thin-film microelectronics where a single device component can do multiple tasks simultaneously. Multiferroic materials with the coexistence of at least two ferroic order parameters have the potential for such multifunctional devices. One interesting class of multiferroics is magnetoelectric materials, which concurrently have some form of magnetic and ferroelectric order parameters. The synthesis techniques, properties, and process optimization will be discussed that can impact the direct applications of these aforementioned materials.
10/8UConn Physics Colloquium
UConn Physics ColloquiumFriday, October 8th, 202103:30 PM - 04:30 PMOtheronline
Multi-messenger Autopsies of Stellar Death
The expanding zoo of astronomical transients has become one of the most important driving forces of scientific discovery in extreme astrophysics. Increasingly sophisticated all-sky surveys are uncovering unexpected phenomena that are forcing radical revisions to long-accepted models of massive star evolution and their compact remnant objects. These discoveries, which will increase by orders of magnitude in the upcoming decade, are shaping the priorities of the next generation of science facilities such as the Rubin Observatory, the James Webb Space Telescope, and Extremely Large Telescopes.
I will review how radio-through-X-ray investigations of transients are revolutionizing our understanding of stellar death and its myriad impacts. This includes the terminal and often dramatic evolutionary phases massive stars pass though when approaching core collapse; the physical mechanisms behind the subsequent supernova explosion; and the formation of powerful compact objects that can participate in the explosion dynamics. I will also discuss how the new synergy between electromagnetic, neutrino, and gravitational wave facilities can enable transformative progress towards finally solving the enigma of core collapse by accurately interpreting the multi-messenger signals from the next Galactic supernova, which will first be detected by the global network of neutrino facilities known as the Supernova Early Warning System.
Meeting URL: https://uconn-cmr.webex.com/meet/cab16109
Astronomy SeminarWednesday, October 13th, 202102:00 PM - 03:00 PMOtherOnline
Collisional Dynamics in the Field: Ultra-Wide BH Systems as Sources of GW Signals
Dynamical interactions are known to play an important role in the evolution of dense stellar systems such as globular clusters and galactic nuclei. In contrast, the galactic field (where most of the stellar systems are) is a low-density environment, where strong stellar encounters were thought to be too rare to play any role in collisional dynamics. However, the low density in the field also allows for the existence of long-lived ultra-wide systems which would have been quickly destroyed in a dense environment. The large separation of such binaries can therefore compensate for the low densities and still allow for relatively high rates of interactions with field stars. Such interactions change the orbital properties of the binaries or outer binaries in the case of triples. Therefore, when considering the evolution of ultra-wide systems one needs to account for random gravitational interaction with passing stars, flybys, even in low-density environments like the field of the host galaxy. The outcome of the interactions between ultra-wide black-holes (BH) systems with random field stars may excite the eccentricity of the system sufficiently to radiate gravitational waves (GW) and drive the system to a merger within Hubble time. This channel may explain a fraction of the current observed binary BH merger rate and provides predictions for future observational runs, e.g. eccentric mergers. The underlying dynamics of this channel is not unique to BH or GW sources, and have implications to other stellar exotica such: low-mass X-ray binaries, Type Ia SNe, main sequence - white dwarf collisions, and more.
Meeting URL: https://uconn-cmr.webex.com/meet/drl20003Contact Information: Grad Student D. Lipman More
10/15Graduate Student Seminar
Graduate Student SeminarFriday, October 15th, 202112:15 PM - 01:15 PMStorrs CampusGS-119
Our Galaxy’s Center: a Window into the High-Redshift Universe
Galaxy centers are the hubs of activity that drive galaxy evolution, from supermassive black holes to dense stellar clusters and feedback from newly-formed stars. Our own galaxy’s center has properties (densities, temperatures, and turbulent line widths) that are reminiscent of galaxies at the peak of cosmic star formation, but in our own cosmic backyard, where the interplay of these physical processes can be resolved in detail. In this talk, I will discuss gas inflow into our Galaxy’s Center, properties of the gas, and incipient star formation. I will discuss simulations of gas flows into the Galactic Center, which are thought to contribute to the unusual properties of star formation in this region, namely that it is producing 10x fewer stars than predicted by standard scaling relations. I will describe observations of the gas and incipient star formation in this region, as well as discuss efforts to measure whether or not this unusual environment results in a change to the Initial Mass Function.
10/15CANCELLED Dr. Steve Mirmina, NASA (UConn Physics Colloquium)
CANCELLED Dr. Steve Mirmina, NASA (UConn Physics Colloquium)Friday, October 15th, 202103:30 PM - 04:30 PMOtherCANCELLEDCANCELLED
Dr. Steve Mirmina, NASA (UConn Physics Colloquium)
Title and abstract: TBD
10/18Particle, Astrophysics, And Nuclear Physics Seminar
Particle, Astrophysics, And Nuclear Physics SeminarMonday, October 18th, 202102:00 PM - 03:00 PMOtheronline
Precision calculation of the x-dependence of PDFs from lattice QCD
The large-momentum effective theory (LaMET) is a general approach to calculate parton physics in high-energy scatterig from lattice gauge theory. In this approach, one approximates light-cone parton observables by time-independent Euclidean matrix elements in a boosted hadron state, and then extracts the former by performing a power expansion at large hadron momentum. With the subleading power corrections suppressed by the hadron momentum, the parton observable is obtained from the leading-power contribution through perturbative QCD running and matching, which therefore can be systematically improved. In this talk, we present a model-independent calculation of the x-dependence of pion valence PDF with LaMET, where we adopt the most up-to-date developments on the systematic corrections, including the hybrid renormalization scheme that rigorously renormalizes the lattice matrix elements at both short and long distances, as well as the next-to-next-to-leading matching kernel for extracting the PDF. As a result, we are able to make predictions for the PDF within a range of $x$ where the systematic uncertainties are under control, which is a firm step towards high-precision calculation.Contact Information: Prof. Luchang Jin More
10/22UConn Physics Colloquium
UConn Physics ColloquiumFriday, October 22nd, 202103:30 PM - 04:30 PMStorrs CampusGant North 20 (formerly IMS-20)
The 2021 Nobel Prize in Physics
The 2021 Nobel Prize in Physics, awarded to Syukoro Manabe, Klaus Hasselmann, and Giorgio Parisi, recognizes contributions key to understanding complex systems and strategies to predict their evolution with time. The forecasting of climate change, although rooted in simple laws of conservation of mass, momentum, and energy is an example of one such complex system in which longer time trends must be extracted from a background of short-term cycles and a near white noise behavior of small spatial and temporal variations in data. This Nobel Prize recognizes the seminal work of Manabe, in advancing the sophistication of computational climate modeling, and the work of Hasselmann, in the statistical treatment of small-scale spatial and temporal variations in climate models and data. Their combined work has enabled a confident extraction of an anthropomorphic fingerprint of greenhouse gas additions to our climate. The work of Giorgio Parisi centers on the statistical treatment of complex systems existing in competing and evolving states. It originated in predicting the behavior of spin glasses in which the spin state of neighboring electrons of iron form an amorphous glass-like structure. Parisi’s work has found applications in a broad range of sciences in which the evolution of competing states cannot accurately be predicted by a search for a stable equilibrium configuration.Contact Information: Prof. P. Mannheim More