KICP Seminars & Colloquia

KICP Seminars & Colloquia, Summer 2018
Seminar schedule for Summer 2018
June 29, 2018 Friday noon seminar  Jo Bovy The University of Toronto  Mapping the Milky Way in 6D with Gaia [Abstract] 
July 5, 2018 Open Group seminar  Sebastian Bruggisser DESY  Electroweak Baryogenesis through varying Yukawas in Composite Higgs models [Abstract] 
July 9, 2018 Astronomy Special Seminar  Vasiliki Pavlidou University of Crete  The Drunken Trek of UltraHighEnergy Cosmic Rays Through The Magnetic Field of the Milky Way [Abstract] 
July 26, 2018 Open Group seminar  Santiago Casas CEA ParisSaclay  Dark Energy with Euclid [Abstract] 
August 15, 2018 Special seminar  Marius Millea IAP  Optimal CMB Lensing Reconstruction and Improved Constraints on Primordial Gravitational Waves [Abstract] 
September 17, 2018 Open Group seminar  Matt Lewandowski IPhT  Analytic IRresummation for the BAO peak [Abstract] 
September 21, 2018 Special seminar  Robert Kirshner Clowes Research Professor of Science, Harvard University Chief Program Officer for Science, Gordon and Betty Moore Foundation  From the Accelerating Universe to Accelerating Science [Abstract] 
FRIDAY NOON SEMINARS
 June 29, 2018  12:00 PM  ERC 401  Friday noon seminar
Mapping the Milky Way in 6D with Gaia Jo Bovy, The University of Toronto
One of the main goals of Gaia, a new astrometric satellite mission, is to provide an empirical measurement of the distribution of stars in the 6+N dimensional space of position, velocity, age, mass, elemental abundances, color, magnitude, etc.. Knowledge of this empirical distribution will allow the formation, evolution, and dynamics of the Milky Way to be strongly constrained. I will give an overview of the Gaia mission and discuss novel methods to map the Milky Way in position and velocity using the billionstar Gaia catalog. I will then discuss results on the stellar content and dynamics of the solar neighborhood from applying these techniques to Gaia's first and second data release. I will also discuss the implications of the structure in the velocity distribution in the extended solar neighborhood observed in Gaia's second data release.
SPECIAL SEMINARS
 August 15, 2018  1:00 PM  ERC 401  Special seminar
Optimal CMB Lensing Reconstruction and Improved Constraints on Primordial Gravitational Waves Marius Millea, IAP
The next generation of CMB experiments are slated to measure the CMB polarization to noise levels and angular resolutions never before probed. One of the most exciting and revolutionary possibilities for this data would be a discovery of the nonzero tensortoscalar ratio $r$, i.e. the first detection of the background of gravitational waves produced by inflation. These gravitational waves are detectable via their impact on CMB Bmode polarization, however the Bmodes are also significantly contaminated by the effects of gravitational lensing. Removing this lensinginduced Bmode foreground (called "delensing") will be necessary to obtain the tightest possible constraints on $r$. While at presentday noise levels, socalled "quadratic estimator" techniques have been massively successful in estimating and removing the lensing contamination, they become statistically suboptimal at the noiselevels of even very nearfuture experiments. It is an open question how to improve upon them, and an exciting one because the potential is to shrink the error bar on $r$ by factors of a few, maybe turning a fewsigma hint of gravitational waves into a full blown discovery! In this talk, I will discuss an optimal Bayesian delensing method which we've developed to solve this problem. In the spirit of this being very much ongoing work, I will tell you about both successes we have had but also roadblocks and outstanding issues. Ultimately, this method can yield not only improved constraints on $r$, but also yield better reconstructions of the lensing potential which can be used in crosscorrelations with various other lowredshift probes of structures.
 September 21, 2018  1:00 PM  ERC 401  Special seminar
From the Accelerating Universe to Accelerating Science Robert Kirshner, Clowes Research Professor of Science, Harvard University Chief Program Officer for Science, Gordon and Betty Moore Foundation
Twenty years ago, astronomers were astonished to learn from observations of exploding stars that cosmic expansion is speeding up. We attribute this to a mysterious “dark energy” that pervades the universe and makes up 70% of it. Scientists are working in many ways to learn more about the nature of dark energy, but our reservoir of ignorance is deep. This talk will summarize the present state of knowledge and look ahead to new ways to use infrared observations of supernovae to improve our grip on dark energy. Accelerating scientific discovery is a mission of the Gordon and Betty Moore Foundation and I will illustrate some of the ways we do that in Chicago and beyond.
OPEN GROUP SEMINARS
 July 5, 2018  3:00 PM  PRC 201  Open Group seminar
Electroweak Baryogenesis through varying Yukawas in Composite Higgs models Sebastian Bruggisser, DESY
Varying Yukawas open new possibilities for electroweak baryogenesis. In this talk I will start by introducing varying Yukawas as a source of CPviolation and explain how baryogenesis can be successful in this framework. I will then present a realization of this paradigm in Composite Higgs models with partial compositeness. Composite Higgs models are, apart from the usual benefits, particularly compelling for this scenario as they feature an intimate link between flavour and Higgs physics. We will see that baryogenesis can be successful in these models if the confinement phase transition happens at the same time as the electroweak phase transition. I will identify regions in parameter space where this is fulfilled and I will compute the baryon yield of those models.
 July 26, 2018  12:00 PM  ERC 401  Open Group seminar
Dark Energy with Euclid Santiago Casas, CEA ParisSaclay
Euclid is an ESA mediumclass mission expected to launch in 2022 that will map the geometry of the Universe by imaging 109 galaxies and measuring 107 galaxy redshifts in 15000 square degrees of the sky. This will provide us detailed information about the accelerated expansion, the evolution of largescale structure and the matterenergy content of the Universe up to a redshift of about z ≈ 2. In this talk, I will review how the main probes of Euclid, namely galaxy clustering and weak lensing, will be able to constrain theories beyond the standard cosmological ΛCDM model and how we will be able to pin down the equation of state of dark energy with about 1% precision. Galaxy clustering measures mainly the movement of tracers along geodesics, while weak lensing is an almost direct mapping of the gravitational potentials at large scales. Using both of these observables, we can obtain valuable information about the growth of perturbations and the geometrical quantities of the Universe and therefore constrain the properties of General Relativity. Since the measurements of Euclid will also give insights on the properties of dark matter and neutrinos at cosmological scales, I will also show how we can measure nonstandard couplings between matter species and dark energy and how we can give tight constraints on many alternative theories of gravity.
 September 17, 2018  10:30 AM  ERC 419  Open Group seminar
Analytic IRresummation for the BAO peak Matt Lewandowski, IPhT
We develop an analytic method for implementing the IRresummation of 1404.5954, which allows one to correctly and consistently describe the imprint of baryon acoustic oscillations (BAO) on statistical observables in largescale structure. We show that the final IRresummed correlation function can be computed analytically without relying on numerical integration, thus allowing for an efficient and accurate use of these predictions on real data in cosmological parameter fitting. In this work we focus on the oneloop correlation function, where the challenge is to reproduce the BAO peak. We show that, compared with the standard numerical integration method of IRresummation, the new method is accurate to better than 0.2%, and is quite easily improvable. We also give an approximate resummation scheme which is based on using the linear displacements of a fixed fiducial cosmology, which when combined with the method described above, is about six times faster than the standard numerical integration. Finally, we show that this analytic method is generalizable to higher loop computations.
ASTRONOMY SPECIAL SEMINARS
 July 9, 2018  12:00 PM  ERC 501  Special Seminar
The Drunken Trek of UltraHighEnergy Cosmic Rays Through The Magnetic Field of the Milky Way Vasiliki Pavlidou, University of Crete
Cosmic rays are charged so that the magnetic field of the galaxy acts as a distorting lens to our view of the ultrahighenergy cosmic ray sky. I will discuss how we can reconstruct this lens and use it to our advantage to investigate both where cosmic rays come from, and what their composition is.
