Talk 1: A Jetted Tidal Disruption: Need for Dynamically-important Magnetic Flux Threading the Supermassive Black Hole // Talk 2: A Brief Introduction to Hamiltonian Monte Carlo

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• Talk 1: Luke Kelley (Harvard) // Talk 2: Michael Betancourt (UCL)
• Thursday 15 August 2013, 14:00-15:00
• Physics West 106.

If you have a question about this talk, please contact Ilya Mandel.

Talk 1: The disruption of a star by a massive black-hole has been a topic of interest for decades. An isotropic, optical transient, with a characteristic light-curve decay had become a well accepted observational signature of such a disruption—-with numerous candidates observed. In 2011 the Swift satellite observed perhaps the most convincing example, and the most unlike expectations. I’ll present Swift J1644 +57 which is believed to be a jetted tidal disruption event, observed in the x-ray and radio, with rapid short-term variability and signs of a stark jet shut-off. The power of the jet suggests a dynamically-important magnetic flux, and flaring in the early light-curve might provide insight into the initial jet formation, and the interplay between black-hole spin and magnetic field. Finally I’ll discuss possible origins of the magnetic flux, which is many orders of magnitude too large to be carried by the disrupted star. We propose that this flux was assembled from a preexisting quiescent accretion disk.

A Brief Introduction to Hamiltonian Monte Carlo

Talk 2: Although they have admitted efficient Bayesian inference in the past, established Markov Chain Monte Carlo algorithms are pushing the limitations of their practicality in the complex models common to scientific data analysis today. In this talk I’ll review both the foundations and recent developments of Hamiltonian Monte Carlo, a technique that leverages tools from mathematical physics to overcome these limitations and provide efficient inference for large and intricate models.

This talk is part of the Astrophysics Talks Series series.

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• Astrophysics Talks Series
• Bham Talks
• Physics West 106
• What's on in Physics?

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