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Northwestern University

Theory Group Meetings 2017-2018

Theory Group Meetings are held at 12:00 PM in Tech F160 (2145 Sheridan Rd) unless otherwise noted

Theory Group Meeting is the informal weekly discussion group of theoretical astrophysicists at CIERA. Discussions usually center around blackboard talks given by graduate students and postdocs at Northwestern, but can include prepared talks given external speakers, as well. Whatever slides or material the speaker brings in, Theory Group Meeting often becomes a quite detailed discussion of the fundamental theoretical astrophysics topic being addressed. Also, while topics under discussion often relate to theory, observational astrophysicists are definitely welcome!

Fall Quarter 2017

  Date Speaker / Seminar
  Sep. 22

Suzanne Aigrain
   University of Oxford
   Taming the Stochastic: How Gaussian Processes are Transforming Exoplanet Studies

Almost all of the staggering progress in detecting and characterizing extra-solar planetary systems over the past 20 years or so has relied on time-series data. The planetary signals are typically buried in complex, correlated noise, such as stellar variability or instrumental systematics, which the "traditional" statistical toolbox of most astronomers was ill equipped to deal with. Over the past few years, Gaussian process (GP) regression has become increasingly popular as a means of modelling these "nuisance signals" explicitly, within a Bayesian framework, so that the resulting uncertainties can be propagated through to the final exoplanet parameters.

I will give a brief historical overview of how this has come about, drawing from my own experience with transmission and eclipse spectra of hot exoplanets, and radial velocity searches for planets around active stars. I will highlight the importance of having a fully specified generative model for one's data set, which can be used for simulations as well as regression, and reflect on the new possibilities which are opening up thanks to the increasing availability of highly scalable GP regression tools. Finally, I will discuss some new ways in which GPs are likely to impact the field of exoplanets even further in the future, including GP classifiers for automated vetting of transiting planet candidates, and Bayesian quadrature to model radial velocity and/or astrometry observations of stars hosting an unknown number of planets.

  Sep. 29

Phil Cowperthwaite
   Harvard University


Chelsea Harris
   UC Berkeley

  Oct. 6

Paz Beniamini
   George Washington University

  Oct. 27

Aleksey Generozov
   Columbia University

  Nov. 17

Dan Stevens
   Ohio State University

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Past Theory Group Meetings