University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Monday, November 4th 2019
12:15 pm:
Speaker: Sharan Banagiri, UMN
Subject: Hyper-parametric Bayesian searches for a BBH background and methods for measuring anisotropies

The Advanced LIGO and Advanced Virgo detectors have detected ten binary-black hole (BBH) mergers in the first two observing runs and many new candidate events in the ongoing third observing run. These BBH detections has been immensely useful as a probe of population statistics, formation rates and merger rates of the progenitor black holes, enabling us to observe a population an entirely new astrophysical population. However, in addition to these detected events there exists a background of a much larger number of mergers which are not individually detectable. This background has traditionally been a target for cross-correlation based stochastic searches by LIGO and Virgo. The statistics of this ensemble of mergers encode much information of astrophysical and cosmological interest. A new method first developed by Smith and Thrane using BBH parameter estimation with Bayesian hyperparameter analysis, promises to be much more sensitive to this background and its properties than cross-correlation methods. In this talk I will describe this new technique and how population properties can be extracted using it. I will also describe ongoing work to use this technique to study the angular and spatial distributions of the binary black hole merger distribution. I will also sketch a statistical formalism to combine the information from the binary black hole spatial distribution with electromagnetic tracers like galaxy counts, to study the structure of the universe at the scales simultaneously accessible to both probes.

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