12:00–1:00 pm Zoom
Host: Vikram Dwarkadas
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Nora Bailey (UChicago) "Planetary Period Ratio Sculpting Near Second-Order Mean-Motion Resonances"
Second-order mean-motion resonances between planets lead to an interesting phenomenon in the sculpting of the period ratio distribution due to their shape and width in period-ratio/eccentricity space. As the osculating periods librate in resonance, the time-averaged period ratio approaches the exact resonance location. The width of second order resonances increases with increasing eccentricity, and thus more eccentric systems have a stronger peak at the resonance location when averaged over sufficient time. The libration period is short enough that this time-averaging behavior is expected to appear on the timescale of the Kepler mission. In this talk, I will present results obtained from N-body integrations of simulated planet pairs near the 5:3 and 3:1 mean-motion resonances. I will demonstrate how these results constrain the eccentricity distributions of real Kepler planets near second-order resonance, placing an upper limit on the Rayleigh scale parameter, σ, at σ = 0.245 (3:1) and σ = 0.095 (5:3) at 95% confidence.
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Anastasia Sokolenko (UChicago) "Intergalactic medium as a probe of fundamental physics"
Most of the volume of the Universe consists of the Intergalactic Medium (IGM), space between collapsed structures like galaxies and galaxy clusters. Extragalactic photons and charged particles that propagate through the Universe spend most of their time in the IGM and can be influenced by its properties. In this talk, I will present a few examples of how we can study fundamental physics from IGM-particles interaction. These include constraints on new light feebly interacting particles as dark photons and axions from resonant photon-new particle conversion, measurement of the intergalactic magnetic field and its influence on ultrahigh-energy cosmic rays and gamma-rays propagation, studying properties of DM using Ly-alpha forest.
