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TAP Colloquia on YouTube

TAP - University of Arizona (TAP at UA)

TAP - University of Arizona (TAP at UA)
YouTube Video VVVnalEtOEJOZVZrWklHUDlnMndTQkRRLmJIMW95S3laVzNj University of Arizona, Theoretical Astrophysics Program (TAP) Cosmology Initiative Lectureship Series TITLE: Beyond the Observable: A Machine Learning Perspective on Modern Cosmology ABSTRACT: Our observations have painted a simple portrait of cosmic evolution, yet fundamental questions remain unanswered: What is the nature of dark matter, the invisible substance that makes up most of the matter in the Universe? What is driving the accelerated expansion of the cosmos? How did it begin? Addressing these questions demands integrating advances in machine learning, high-performance computing, and astrophysics. In this talk, I will present frameworks that bridge the gap between numerical simulations and increasingly precise astronomical observations to decode these invisible components. I will demonstrate how generative models can analyze astronomical data at its full complexity, while remaining robust to uncertainties in galaxy formation physics. This allows us not only to reconstruct the dark matter distribution and primordial Universe from observed galaxy clustering, but also to identify potential anomalies that might signal new physics beyond our standard cosmological model. These advances come at a pivotal moment, as we enter an era of extremely precise cosmological surveys that may transform current statistical tensions into discoveries of new fundamental physics. BIO: Carol is an IAIFI Fellow at the NSF Institute for Artificial Intelligence and Fundamental Interactions. She splits her time between MIT and the Center for Astrophysics at Harvard, developing robust machine learning models that can guide us towards future discoveries in physics. Carolina received her Ph.D. in Physics and Data Intensive Science from the Institute of Computational Cosmology at Durham University, UK, in 2022. Alongside her PhD, she has been a research collaborator with the United Nations (UN) Global Pulse and the UK’s National Health Service (NHS), developing epidemiological simulations, and a research intern at Amazon’s Alexa team. She is also passionate about science communication and making astrobabble understandable.
University of Arizona, Theoretical Astrophysics Program (TAP) Cosmology Initiative Lectureship Series TITLE: Beyond the Observable: A Machine Learning Perspective on Modern Cosmology ABSTRACT: Our observations have painted a simple portrait of cosmic evolution, yet fundamental questions remain unanswered: What is the nature of dark matter, the invisible substance that makes up most of the matter in the Universe? What is driving the accelerated expansion of the cosmos? How did it begin? Addressing these questions demands integrating advances in machine learning, high-performance computing, and astrophysics. In this talk, I will present frameworks that bridge the gap between numerical simulations and increasingly precise astronomical observations to decode these invisible components. I will demonstrate how generative models can analyze astronomical data at its full complexity, while remaining robust to uncertainties in galaxy formation physics. This allows us not only to reconstruct the dark matter distribution and primordial Universe from observed galaxy clustering, but also to identify potential anomalies that might signal new physics beyond our standard cosmological model. These advances come at a pivotal moment, as we enter an era of extremely precise cosmological surveys that may transform current statistical tensions into discoveries of new fundamental physics. BIO: Carol is an IAIFI Fellow at the NSF Institute for Artificial Intelligence and Fundamental Interactions. She splits her time between MIT and the Center for Astrophysics at Harvard, developing robust machine learning models that can guide us towards future discoveries in physics. Carolina received her Ph.D. in Physics and Data Intensive Science from the Institute of Computational Cosmology at Durham University, UK, in 2022. Alongside her PhD, she has been a research collaborator with the United Nations (UN) Global Pulse and the UK’s National Health Service (NHS), developing epidemiological simulations, and a research intern at Amazon’s Alexa team. She is also passionate about science communication and making astrobabble understandable.
University of Arizona, Theoretical Astrophysics Program (TAP) Planet Formation Initiative Series and SO/NSF NOIRLab Joint Colloquium TITLE: Effects of Clusters on their Constituent Planetary Systems ABSTRACT: Most stars -- and most solar systems -- form within groups and clusters. The principle objective of this talk is to explore how these star forming environments affect the solar systems forming within them via three channels: dynamical interactions, elevated radiation fields, and increased particle fluxes. The discussion starts with the dynamical simulations, which are used to study how cluster evolution depends on system size and initial conditions. Multiple realizations of equivalent cases are used to build up a statistical description of these systems, e.g., distributions of closest approaches and radial locations. These results provide a framework from which to assess the effects of clusters on solar system formation. Distributions of radial positions are used in conjunction with UV luminosity distributions to estimate the radiation exposure of circumstellar disks. Photo evaporation models determine the efficacy of radiation in removing disk gas and compromising planet formation. The distributions of closest approaches are used in conjunction with scattering cross-sections to determine probabilities for solar system disruption. Finally, we determine the distributions of radioactive nuclei and cosmic rays that are provided to circumstellar disks, where they enhance ionization and heating. This work provides a quantitative determination of the effects of clusters on forming solar systems. As an application, these results are used to place constraints on the possible birth environments for our own Solar System. BIO: Born in Redwood City, California, Fred Adams graduated from Iowa State University in 1983 with a BS in Physics and Mathematics. He went on to receive his PhD in Physics from the University of California, Berkeley (in 1988), where his dissertation received the Robert J. Trumpler Award from the Astronomical Society of the Pacific. After serving as a postdoctoral research fellow at the Harvard-Smithsonian Center for Astrophysics, Adams joined the faculty in the Physics Department at the University of Michigan in 1991. Adams was promoted to Associate Professor in 1996, and to Full Professor in 2001. He is the recipient of the Helen B. Warner Prize from the American Astronomical Society and the National Science Foundation Young Investigator Award. At the University of Michigan, he has been awarded the Excellence in Education Award, the Excellence in Research Award, the Faculty Recognition Award, and was elected to the Michigan Society of Fellows. Adams was subsequently elected to be a fellow of the American Physical Society, fellow of the American Astronomical Society, and Chair of the AAS Division on Dynamical Astronomy. He was named as the Ta-You Wu Collegiate Professor of Physics at the University of Michigan, and is currently the director of the Leinweber Center for Theoretical Physics. Professor Adams works in the general area of theoretical astrophysics with a focus on the study of star formation, exoplanets, and cosmology. He is internationally recognized for his work on the radiative signature of the star formation process, the dynamics of circumstellar disks, the development of a theory for the initial mass function, and studies of extra-solar planetary systems. In cosmology, he has studied the inflationary universe, magnetic monopoles, cosmic rays, and cosmic background radiation fields. His work in cosmology also includes explorations of the long-term fate and evolution of the universe, as well as a re-examination of its degree of fine-tuning.
University of Arizona, Theoretical Astrophysics Program (TAP) Planet Formation Initiative Lectureship Series and Origins Seminar TITLE: Revisiting the Core Accretion Paradigm for Giant Planet Formation: Analytic Framework for the Late Infall Stage and the Distribution of Planetary Masses ABSTRACT: This talk presents an analytic description for the late stages of giant planet formation, when planets gather the majority of their mass. The resulting solutions show how the protoplanet properties (envelope density distribution, velocity field, column density, disk surface density, system luminosity, and emergent spectral energy distributions) vary with the input parameters of the problem (instantaneous mass, orbital location, accretion rate, and planetary magnetic field strength). We then construct a framework for calculating the distribution of planet masses resulting from this paradigm. In this scenario, the disk lifetime determines the end of mass accretion onto the planet. The mass accretion rate depends on the size of the Hill sphere, the fraction of the disk accretion flow that enters the sphere of influence, and the efficiency with which the planet captures the incoming material. The resulting model produces a planetary mass function with a nearly power-law form, roughly consistent with current observational estimates. BIO: Born in Redwood City, California, Fred Adams graduated from Iowa State University in 1983 with a BS in Physics and Mathematics. He went on to receive his PhD in Physics from the University of California, Berkeley (in 1988), where his dissertation received the Robert J. Trumpler Award from the Astronomical Society of the Pacific. After serving as a postdoctoral research fellow at the Harvard-Smithsonian Center for Astrophysics, Adams joined the faculty in the Physics Department at the University of Michigan in 1991. Adams was promoted to Associate Professor in 1996, and to Full Professor in 2001. He is the recipient of the Helen B. Warner Prize from the American Astronomical Society and the National Science Foundation Young Investigator Award. At the University of Michigan, he has been awarded the Excellence in Education Award, the Excellence in Research Award, the Faculty Recognition Award, and was elected to the Michigan Society of Fellows. Adams was subsequently elected to be a fellow of the American Physical Society, fellow of the American Astronomical Society, and Chair of the AAS Division on Dynamical Astronomy. He was named as the Ta-You Wu Collegiate Professor of Physics at the University of Michigan, and is currently the director of the Leinweber Center for Theoretical Physics. Professor Adams works in the general area of theoretical astrophysics with a focus on the study of star formation, exoplanets, and cosmology. He is internationally recognized for his work on the radiative signature of the star formation process, the dynamics of circumstellar disks, the development of a theory for the initial mass function, and studies of extra-solar planetary systems. In cosmology, he has studied the inflationary universe, magnetic monopoles, cosmic rays, and cosmic background radiation fields. His work in cosmology also includes explorations of the long-term fate and evolution of the universe, as well as a re-examination of its degree of fine-tuning.
University of Arizona, Theoretical Astrophysics Program T(AP) Colloquia Series TITLE: A Case for Mars Terraforming Research ABSTRACT: Diverse perspectives inform research on planetary environmental modification. Building on pioneering work by Carl Sagan, we now understand Mars as a world that once sustained rivers and lakes before experiencing global cooling - presenting unique opportunities for understanding planetary habitability changes. Some argue that a hospitable Mars could enable greater self-sufficiency compared to isolated outposts. Others are motivated by the scientific desire to learn about the universe, as the realization of humanity's dreams to explore the universe is assisted by expanded human presence. While some advocate preserving Mars in its current state, research can transform abstract debates into concrete technical assessments. A key scientific challenge in making Mars's surface suitable for Earth-like life is understanding planetary temperature modification. Recent advances in engineered-aerosol warming approaches, (e.g. Ansari et al. Science Advances 2024) demonstrate unprecedented mass-efficiency (5000x compared to traditional methods), opening new possibilities for stepwise research into planetary temperature modification. I will discuss what we know about Mars, what we think we know about Mars terraforming, including alternative approaches, and suggest priorities for future research. As we evaluate approaches ranging from minimal intervention to more extensive modification, we must rigorously assess technical requirements, resource efficiency, and risk management. While full planetary environmental enhancement would span multiple centuries, immediate research priorities can focus on understanding fundamental physical, chemical, and biological constraints that will shape any future decisions about Mars. BIO: Edwin Kite is a Resident at Astera Institute in Emeryville, CA, an associate professor with tenure at the University of Chicago, and a participating scientist on the Mars "Curiosity" rover. Following undergraduate work at the University of Cambridge, Kite moved to UC Berkeley for a PhD in the Earth and Planetary Science Department. Prior to joining the University of Chicago, Kite held prize postdoctoral fellowships at Caltech and at Princeton. Kite is a co-recipient of the Newcomb Cleveland Prize and a recipient of the AGU Greeley Early Career Award. Kite's research interests include Early Mars, small-radius exoplanets, and Mars terraforming.
University of Arizona, Theoretical Astrophysics Program (TAP) Colloquia Series TITLE: Electromagnetic Transients in the Disks of Active Galactic Nuclei ABSTRACT: The disks of Active Galactic Nuclei (AGNs) have emerged as interesting environments for the evolution of stars and the compact objects they leave behind. The very high density of the medium, combined with torques from the gas, yield evolutionary paths for main sequence stars which differ from those in typical galaxies. Well known transient phenomena such as long and short GRBs may have a different-than-usual appearance when emerging from AGN disks, and new astrophysical phenomena, such as the accretion induced collapse of neutron stars to black holes, may be commonplace in AGN disks. BIO: Rosalba Perna is a theoretical astrophysicist with a broad range of research interests, spanning high-energy astrophysics, cosmology, and exoplanets. She earned her undergraduate degree in Physics, as well as a conservatory degree in piano, in Italy. She then obtained her Ph.D. in Physics at Harvard University, followed by appointments as a Harvard Junior Fellow and a Lyman Spitzer Fellow at Princeton University. Dr. Perna has held faculty positions at the University of Colorado Boulder and, since 2014, at Stony Brook University, where she is a professor and served as Associate Chair of the Department of Physics and Astronomy from 2021 to 2024. She was elected a Fellow of the American Physical Society in 2014.
University of Arizona, Theoretical Astrophysics Program (TAP) Cosmology Initiative Lectureship Series TITLE: Representation Learning: A Causal Perspective ABSTRACT: Representation learning constructs low-dimensional representations to summarize essential features of high-dimensional data like images and texts. Ideally, such a representation should eliciently capture non-spurious features of the data. It shall also be disentangled so that we can interpret what feature each of its dimensions captures. However, these desiderata are often intuitively defined and challenging to quantify or enforce. In this talk, we take on a causal perspective of representation learning. We show how desiderata of representation learning can be formalized using counterfactual notions, enabling metrics and algorithms that target elicient, non-spurious, and disentangled representations of data. We discuss the theoretical underpinnings of the algorithm and illustrate its empirical performance in both supervised and unsupervised representation learning. This is joint work with Michael Jordan, Kartik Ahuja, Divyat Mahajan, and Yoshua Bengio. BIO: Wang is an assistant professor of statistics at the University of Michigan. She works in the fields of Bayesian statistics, machine learning, and causal inference. Previously, she was a postdoctoral researcher with Professor Michael Jordan at the University of California, Berkeley. She completed her PhD in statistics at Columbia, advised by Professor David Blei, and her undergraduate studies in mathematics and computer science at the Hong Kong University of Science and Technology. Her research has been recognized by the j-ISBA Blackwell-Rosenbluth Award, ICSA Conference Young Researcher Award, ISBA Savage Award Honorable Mention, ACIC Tom Ten Have Award Honorable Mention, and INFORMS data mining and COPA best paper awards.
University of Arizona, Theoretical Astrophysics Program (TAP) Colloquia Series TITLE: Testing Inflation and the Standard Cosmological Model with the Cosmic Microwave Background ABSTRACT: Inflation--the leading model for the earliest moments of the time, in which the Universe undergoes a period of rapid, accelerating expansion -- generically predicts a background of primordial gravitational waves, which generate a B-mode component in the polarization of the cosmic microwave background (CMB). The measurement of such a B-mode signature would lend significant support to the paradigm of inflation. However, observed B modes also contain a component from the gravitational lensing of primordial E modes, which can obscure the measurement of the primordial B modes. We reduce the uncertainties in the B-mode measurement contributed from this lensing component by a technique called 'delensing.’ In this talk, I will show results of the first and only analysis that reduces cosmological parameter uncertainty, in this case the uncertainty on the tensor-to-scalar ratio from the BICEP/Keck experiments, with delensing. For upcoming analyses, efficient delensing relies on high signal-to-noise measurements of the CMB lensing mass map. Such lensing maps not only will be essential for testing inflation, they will also provide new cosmological information compared to the primary CMB. This is particularly interesting in light of the current tensions between inferred parameter values of the standard cosmological model LCDM such as the Hubble parameter using different data sets. I will show the latest state-of-the-art measurement of CMB lensing using data from the South Pole Telescope, its cosmological parameter constraints, and discuss implications for cosmic tensions and the sum of neutrino masses. BIO: Kimmy Wu is an observational cosmology specializing the cosmic microwave background. She is interested in using CMB and large-scale structure data to probe inflation, test the standard model of cosmology LCDM. and find new physics. She completed her undergraduate studies at the University of Michigan at Ann Arbor, did her PhD at Stanford University, and postdoc-ed at UC Berkeley and UChicago before joining SLAC as a Panofsky Fellow.
University of Arizona, Theoretical Astrophysics Program (TAP) Dynamics Initiative Computational Workshop TITLE: Orbital Dynamics in Python OVERVIEW: This computational workshop will provide a hands-on introduction to the REBOUND N-body integration package. We will introduce some of the basics, discuss its new visualization tools, as well as go through how to customize the code for your own scientific goals. We will then show how various common astrophysical effects (tides, oblateness, radiation pressure etc.) can be easily incorporated using the REBOUNDx library, and how you can add your own custom effects. Finally, we will introduce celmech, a new Python package for facilitating theoretical orbital mechanics calculations, and isolating the effects of resonances, secular dynamics, and much more!
University of Arizona, Theoretical Astrophysics Program (TAP) Dynamics Initiative Lectureship TITLE: Toward a Theory of How Chaos Drives Dynamical Instabilities and Shapes Compact Exoplanet Systems ABSTRACT: While several processes are thought to be important in the early phase of planet formation, most theories converge on a final stage dominated by giant impacts that set the ultimate masses and orbital architectures that we observe today in exoplanet systems. Nevertheless, despite enormous theoretical effort, we do not yet fully understand the dynamical processes driving chaos in such systems, and we are unable to predict a priori which regions in the space of possible orbital configurations will be long-term stable, and which will lead to instability. As a motivation, I will first present our recent work suggesting that dynamical instabilities have indeed strongly shaped the observed distribution of exoplanetary systems. I will then survey our current understanding of chaos in planetary systems, discuss recent theoretical developments, and close with a roadmap of ongoing work and open questions. BIO: Dan Tamayo is an assistant professor in the physics department at Harvey Mudd College in the greater Los Angeles area. He grew up in northern Spain, was a Peace Corps volunteer in Namibia, and obtained his Ph.D. in Astronomy & Space Sciences at Cornell University. Before joining the faculty at Harvey Mudd College he was a Centre for Planetary Sciences postdoctoral fellow at the University of Toronto and a NASA Sagan fellow at Princeton. His graduate work with the Cassini mission around Saturn focused on the collisional evolution of Saturn's small, distant irregular satellites. His subsequent work has focused on numerical integration algorithms for planetary orbital dynamics as a lead developer of the REBOUND N-body package, and on theoretical and machine learning approaches to predicting the stability of exoplanet orbital configurations.
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