Workshops & Events
EFI colloquium: Damiano Caprioli, "On the origin of the cosmic radiation - 70 years later (a tribute for Fermi's pioneering paper of 1949)"
January 7, 2019 | PRC 201 | 4:15 PM | Event
A theory of the origin of cosmic radiation is proposed according to which cosmic rays are originated and accelerated primarily at the blast waves of supernova remnants and in relativistic jets of active galactic nuclei. One of the features of the theory is that it yields naturally a power law for the spectral distribution of the cosmic rays and explains in a straightforward way the heavy nuclei observed in the primary radiation.

PSD colloquium: Pierre-Louis Lions, College de France, "Mean Field Games: What? Why? How?"
February 1, 2019 | Kent Hall 120 | 4:00 PM | Event
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Mathematics presents Pierre-Louis Lions, Professor, College de France

Pierre-Louis Lions is one of the most well known mathematicians of our time. He graduated from the Ecole Normale Superieure in 1977, and received his doctorate from the University of Pierre and Marie Curie in 1979.

His main work is on the theory of nonlinear partial differential equations. He received the Fields Medal (comparable to a Nobel Prize) for his work in 1994. Lions was the first to give a complete solution to the Boltzmann equation with proof. He has received numerous other awards. Currently, he holds the position of Professor of Partial differential equations and their applications at the prestigious College de France in Paris as well as a position at Ecole Polytechnique.

In the paper "Viscosity solutions of Hamilton-Jacobi equations" (1983), written with Michael Crandall, he introduced the notion of viscosity solutions. This has had a great effect on the theory of partial differential equations. More recent work includes the theory of mean-field games, which promises to be highly influential in economics.

Pierre-Louis Lions has also been interested for a long time in mathematical finance writing seminal papers on a variety of subjects, such as the use of Malliavin calculus, Monte Carlo methods, applications of stochastic control, and convexity properties.

Physics colloquium: Marc Kamionkowski, Johns Hopkins University, "Heretical hypotheses in the hunt for dark matter"
February 21, 2019 | MGM Lecture Hall, KPTC 106 | 3:30 PM | Event
We have known for a reasonable fraction of a century that most of the matter in the Universe is dark, and for several decades that it cannot be baryonic. The nature of this dark matter has, however, been elusive. The prevailing weakly- interacting massive particle (WIMP) hypothesis that have long been theorists preferred guess faces considerable pressure from an array of null searches, and this has led theorists to consider previously unpalatable alternatives. I will discuss the rise, and possible fall, of an idea that connected LIGOs discovery of black-hole binaries to dark matter. I will also discuss recent ideas (motivated in part by an intriguing recent experimental result) that involve particles with enhanced couplings to ordinary matter.

Midwest Workshop on Supernovae and Transients
February 25 - 26, 2019 | Chicago, IL | Event
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The purpose of the workshop is to bring together the Midwest community interested in supernovae of all types, and Galactic and extragalactic transients in general, including kilonovae, fast radio bursts, TDEs, gamma-ray bursts, novae, X-ray binaries, and anything that varies on a short timescale. We will deal with all aspects of these objects, including the explosion mechanism, progenitors, evolution, nucleosynthesis, and radiation over all wavelengths from radio to gamma-rays.

Ample time would be given to students and postdocs, and significant time reserved for discussions.

The workshop is organized by the Department of Astronomy and Astrophysics at the University of Chicago.

Broader Horizons: Stephen Hoover, Civis Analytics
March 7, 2019 | ERC 401 | 5:30 PM | Event
Organizer: Andrew Neil

Interested in a career in data science? What does a data scientist do, exactly, and how does a physicist or astronomer become a data scientist? Stephen is a data scientist at the Chicago-based company Civis Analytics, where he helps to build predictive modeling tools for Civis's software offerings and consulting work. He received his PhD in physics from UCLA, and went on to work with the South Pole Telescope group as a postdoc. He joined Civis Analytics in 2014, and in this talk, will discuss his transition from academia and the current nature of a data scientist's job.

Winter 2019 Postdocs Symposium
March 8, 2019 | ERC 401 | 12:00 PM | Event
12:00PM - 12:45PM   Lunch

12:45 - 1:00   Dimitrios Tanoglidis
"Shadows in the dark: searching for Ultra Diffuse Galaxies in the DES data"
Recent astronomical surveys have provided unprecedented sensitivity to extremely low surface brightness "ultra-diffuse" galaxies. These extreme galaxies have sizes comparable to that of the Milky Way (radii 1.5 -10 kpc), but stellar content ~1% of it (central surface brightness μ,0 ∼ 24 − 26 mag arcsec−2). This makes UDGs some of the most dark-matter-dominated systems known. It is currently unclear whether UDGs and more compact field dwarf galaxies have a common or whether their formation is fundamentally different. In this talk I will give a review of the current theoretical and observational literature and I will show how the Dark Energy Survey (DES) will be important for addressing the global distribution of environments for UDGs, as well as some preliminary results of this search.

1:00 - 1:30   Marco Raveri

1:30 - 2:00   Nesar Ramachandra
"Variational autoencoders for the emulation of cosmological functions"
Future cosmological surveys demand high precision requirements on the estimation of cosmological parameters. Substantial improvements on calibration have been achieved using fast emulators of cosmological functions. We present a novel approach to Gaussian process emulation by using an unsupervised learning algorithm of Variational Autoencoders. We compare it to the more classical principal component decomposition. A specific application of CMB power spectra is shown to achieve sub-percent level errors over wide ranges of cosmological parameters.

2:00 - 2:15   William Wolf
"Instabilities in Cosmological Models Beyond LCDM"
Explaining the observed accelerated expansion of our universe is an important challenge within the current theoretical framework of physics. This question has inspired the development of theories beyond the standard Lambda-CDM paradigm that invoke dynamical models of dark energy or more direct modifications of gravity. In this talk, I will discuss the presence of ghost, gradient, and tachyonic instabilities within these models and how they impact their viability. I will also look at how we can use canonical transformations to highlight the relationship between these three pathological instabilities.

2:15 - 2:30   Hanjue Zhu
"Cosmic Reionization On Computers: Reionization Histories of Present-day Galaxies"
The gas content in the present day intergalactic medium (IGM) between galaxies is highly ionized. The history and sources of this ionization is one of the outstanding question in studies of galaxy formation. One of the interesting topics in reionization studies is ionization histories of individual galaxies, including the Milky Way. We examine the reionization history of present-day galaxies in numerical simulations from the Cosmic Reionization On Computers project. We use three $40,h^{-1},{m Mpc}$ reionization simulations to study the neutral fractions at positions of particles that belong $z=0$ halos during rapid global reionization, $6lsim zlsim 9$. We find a systematic trend of reionization redshift with mass - present day halos with higher masses have earlier reionization times.

2:30 - 3:00   Reed Essick
"Non-parametric Inference with Gravitational-Waves and Other Things I think About"
I'll discuss a few uses for non-parametric inference within the context of well resolved Gravitational-Waves events that I'm currently working on, focusing on inferring the Equation of State of dense nuclear matter but also describing preliminary work on detecting anisotropic merger distributions. With the third observing run (O3) starting in April, I'll also discuss how this work connects to my general excitement and fear of the coming data.

3:00 - 3:30   Coffee break

3:30 - 4:00   Brian Nord
"AI in astrophysics and the ethics of AI applications"

4:00 - 4:15   Joao Caldeira
"Quantum Machine Learning for Astrophysics"
While the era of quantum supremacy is not upon us yet, recent developments make it clear that, like winter, it is coming. In this talk I will present preliminary results, roadblocks, and successes in training machine learning models for classification of astrophysical objects with quantum annealers. We hope that the lessons learned will prove useful as computers with more qubits become available.

4:15 - 4:30   Georgios Zacharegkas
"Galaxy-galaxy weak lensing with HOD"
One of the most powerful probes of the relation between dark matter halos and the galaxies they host is galaxy-galaxy weak lensing. Modeling this phenomenon requires very careful treatment of the various contributions to the final signal from central and satellite galaxies. At small scales the main contribution comes from matter distribution inside the lens dark matter halo. Correlations with neighboring halos start to dominate at large scales. We use the framework of the Halo Occupation Distribution (HOD) to fit the model to data and constrain the mass of the lens halo. Our data for the lenses consists of redMaGiC galaxies over a wide range of redshift, 0.2 < z < 0.8. We demonstrate that with our numerical tools we are able to constrain the model parameters and deduce the mass of the lens halo. The same tools can be applied to a wide variety of lenses, thus enabling us to explore the relation between dark matter and galaxies of different types.

4:30 - 5:00   Meng-Xiang Lin
"Separate universe and consistency relation beyond slow-roll inflation"
We clarify the difference between various gauge-invariant quantities typically used in inflation. We show that whereas inflationary consistency relations are calculated to the unitary curvature $zeta_u$, the separate universe condition is determined by the synchronous curvature $zeta_s$. Due to this difference, the separate universe is not enough to have consistency relations, which we illustrate with an explicit example. In addition, we show that the comoving curvature, typically used for evolving primordial perturbations after inflation, does not always coincide with the unitary curvature outside the horizon. This difference must be taken into account when translating inflationary quantities to initial conditions for the universe during radiation and matter domination.

5:00 - 5:30   Yu-Dai Tsai
"Multi-messenger Searches for Dark Matter: Quiet Kilonova, Light Black Hole, and Neutron Star Merger Distribution"
Dark matter-induced neutron star implosions could give astrophysical signatures including light (~ 1-2 solar mass) black hole mergers, quiet kilonova, and potentially, fast radio bursts. The implosions can significantly change the spatial distribution of the neutron star merger events in galaxies, allowing us to explore some dark matter parameter space 5 - 10 orders of magnitude in cross-section beyond the reach direct detection experiments. The implosions also explain peculiar pulsar distribution near the galactic center. We explore all these signatures and detail an updated search for kilonovae in the Dark Energy Survey and a Dark Energy Camera telescope proposal, partly motivated by finding a quiet kilonova. This work is based on arXiv:1706.00001 (PRD '18).

5:30 - 6:30   Reception


Sara Seager, "Exoplanets and the Search for Habitable Worlds"
April 9, 2019 | School of the Art Institute of Chicago, 112 South Michigan Ave., MacLean Ballroom | 6:00 PM | Event
Sara Seager, 2019 Brinson Lecturer
Sara Seager is an astrophysicist and planetary scientist at MIT. Her science research focuses on theory, computation, and data analysis of exoplanets. Her research has introduced many new ideas to the field of exoplanet characterization, including work that led to the first detection of an exoplanet atmosphere. She received her Ph.D from Harvard University in 1999. Before joining MIT in 2007, Professor Seager spent four years on the senior research staff at the Carnegie Institution of Washington preceded by three years at the Institute for Advanced Study in Princeton, NJ. Professor Seager is on the advisory board for Planetary Resources. Professor Seager was elected to the National Academy of Sciences in 2015, is a 2013 MacArthur Fellow, the 2012 recipient of the Raymond and Beverly Sackler Prize in the Physical Sciences, and the 2007 recipient of the American Astronomical Society's Helen B. Warner Prize. She has been recognized in the media, most recently in Time Magazine's 25 Most Influential in Space in 2012.

2019 Brinson Lecture: "Exoplanets and the Search for Habitable Worlds"
For thousands of years people have wondered, "Are there planets like Earth?" "Are such planets common?" "Do any have signs of life?" Today astronomers are poised to answer these ancient questions, having recently found thousands of planets that orbit nearby Sun-like stars, called "exoplanets". Professor Sara Seager will share the latest advances in this revolutionary field.

This event is co-sponsored by the University of Chicago and the School of the Art Institute of Chicago.

Workshop: "Astrophysics with the CMB-S4 Survey"
April 15 - 16, 2019 | Chicago, IL | Event
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The purpose of the workshop is to bring together leading astronomers and astrophysicists to integrate the planned CMB-S4 Legacy Survey, a multi-band millimeter wave survey covering roughly half the sky at unprecedented sensitivity and observing cadence, with other directions in astrophysics. This includes the time variable sky as seen in solar system science, stellar variability, binary evolution, supernovae, tidal disruption events, and gamma-ray bursts, as well as high-redshift star formation and studies of feedback from black holes and star formation on the intergalactic medium, including galaxy cluster thermodynamics and reionization.

LSST Dark Matter Workshop
August 5 - 7, 2019 | Chicago, IL | Event
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Dark matter constitutes roughly 85% of the matter density of the Universe, and represents a critical gap in our understanding of fundamental physics. Despite extensive experimental efforts, the only robust, positive empirical measurement of dark matter continues to come from cosmological and astrophysical observations. The Large Synoptic Survey Telescope (LSST) offers a versatile platform to investigate dark matter. This workshop will focus on new ideas for probing the fundamental nature of dark matter with LSST and other future observations.

Potential discussion topics for this workshop Include:
- Warm and self-interacting particle dark matter
- Compact objects
- Ultra-light and fuzzy dark matter
- Near-field cosmology
- Gravitational lensing (weak, strong, and micro)
- Galaxy clusters
- Large scale structure

SCAM-2019: SNIa-Cosmology Analysis Meeting
October 2 - 4, 2019 | Chicago, IL | Event
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The era of large photometrically identified samples of Type Ia Supernovae (SNIa) has begun, opening the door to a variety of cosmological probes. This workshop will focus on analysis methods being applied to current data sets (e.g., CfA, CSP, DES, Foundation, PS1, SDSS, SNf, SNLS) and new methods anticipated for future data sets (e.g., LSST, WFIRST). We will discuss how current methods need to evolve for the challenge of much larger SNIa samples, and also discuss the challenges of developing new analysis methods. This meeting will include presentations with significant discussion time. We have limited travel support for early career scientists.

Conference: Cosmic Controversies
October 5 - 8, 2019 | Gleacher center, Chicago | Event
Gleacher center, Chicago
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Are we close to a fundamental cosmological paradigm, or is a major disruption imminent?

Is cosmology on the verge of a fundamental description of the Universe from a tiny fraction of a second after the big bang until today based upon LCDM, or is it on the cusp of major disruption and re-organization of our understanding of the Universe? Eight cosmic controversies - the value(s) the Hubble constant, viability of CDM, cause of cosmic acceleration, validity of inflation, the existence of a dark matter particle, clarity about the multiverse, origin of ordinary matter, and other loose ends in the paradigm - have much to say about the direction cosmology will take in the next decade and may the answer the question above. Our cosmology conclave will focus on these controversies and address how best to resolve them.

The controversies
  1. What is the resolution of the current H0 discrepancy?
  2. Is a theory beyond Cold Dark Matter needed to describe structure formation?
  3. What is the explanation of Cosmic Acceleration?
  4. Can Inflation be transformed into a fundamental theory of the early Universe?
  5. Do we need the Multiverse and can it made turned into a scientific theory?
  6. Is there a Dark Matter Particle or do we need another explanation for the dark matter phenomenon?
  7. Whither Baryogenesis?
  8. Are we close to Cosmic Convergence or on a path to Cosmic Disruption?


... and what tools are critical for making progress in cosmology in the coming decades?

Conference Format
Eight, 90-minute afternoon panels featuring a moderator/chair and 3 speakers. Forty-some 25-minute invited morning talks that inform the panels, and contributed posters. Evenings include a public event, a banquet and a poster session reception.