TAP Colloquia on YouTube

TAP - University of Arizona (TAP at UA)

YouTube Video VVVnalEtOEJOZVZrWklHUDlnMndTQkRRLjEyWTc4bzdVWDhz

"The movie shows a magnetically regulated filamentary cloud formation. In this scenario,
gas collision at reverse magnetic fields triggers magnetic reconnection. Reconnected fields
(streamlines in the movie) pull gas (color rendering) toward the central axis, resulting in a
filamentary cloud which proceeds to form stars. The physical mechanism shows an active
role of magnetic fields in gas dynamics in the ISM. It is potentially an important mode of
molecular cloud and star formation. See Kong et al. (2021, ApJ, 906, 80) for details."

University of Arizona, Theoretical Astrophysics Program (TAP) Cosmology Initiative Computational Workshop

TITLE:
From Zero to Generative: Learning Generative Models from Scratch

ABSTRACT:
This workshop introduces generative modeling with no prerequisites in machine learning or
deep learning. Starting with basic concepts, we guide participants through the intuition and
implementation of key generative frameworks, such as diffusion models. Participants will gain hands-on
experience building simple versions of these models and understanding when to apply different
architectures.

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 PhD 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.

Load More... Subscribe