Past Events

  • 2019 Dec 10

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room
    The new BHI Fellows will derived a short presentation about their work. Speakers will be: Martin Lesourd (Mathematics/Philosophy), Kevin Nguyen (Physics), Achilleas Porfyriadis (Physics) and Max Zimet (Mathematics/Physics).
  • 2019 Dec 03

    BHI Colloquium

    1:30pm

    Location: 

    BHI Meeting Room

    Xiaohui Fan (University of Arizona)

    Title: The First Luminous Quasars

    Abstract: I will describe the ongoing surveys to discover luminous quasars at the highest redshift. These surveys allow the first measurements of quasar luminosity function at the epoch of reionization, and predict the redshift at which we will find the earliest luminous quasars powered by billion solar mass black holes in the observable universe. I will also update the effort to measure black hole mass function in quasars at the...

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  • 2019 Nov 26

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Wlodek Kluzniak (University of Warsaw)

    Title: Diskoseismic modes in radiative general-relativistic hydrodynamical simulations of thin disks

    Abstract: High frequency quasiperiodic variability in accreting black hole sources is thought to reflect the underlying space-time metric. A detailed analytic theory of normal modes of thin disks has been worked out and can be found in books (e.g., Kato 2016) and review papers (e.g., Wagoner 2008). Other mechanisms, such as resonance resulting in a 3:2 ratio of...

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  • 2019 Nov 19

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Andreas Bauswein (University of Heidelberg)

    Title: The QCD phase transition in neutron star mergers

    Abstract: At low temperature quantum chromodynamics predicts a transition from ordinary hadronic matter to de-confined quark matter at higher densities. Whether or not this transition occurs at densities which are realized in neutron stars is currently unclear. We discuss an unambiguous signature of this phase transition in neutron star mergers. This idea is based on a comparison between information from the...

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  • 2019 Nov 05

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Charles Gammie (University of Illinois)

    Title: The Next Generation of Theory for EHT

    Abstract: The first EHT images were consistent with expectations based on synthetic observations of GRMHD simulations. Analysis of the images combined with other astronomical data provided constraints on the accretion rate, magnetization, and magnitude and direction of the black hole spin. The next generation of EHT images will demand a thorough review of the theory, a clear error budget attached to model uncertainties,...

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  • 2019 Oct 29

    BHI Colloquium

    1:30pm to 3:00pm

    Location: 

    BHI Meeting Room

    David Kaiser (MIT)

    Title: The Price of Gravity: Private Patronage and the Transformation of Gravitational Physics after World War II

    Abstract: This talk (based on research conducted with Dean Rickles) focuses on how various private patrons intervened to support research in gravitational physics from the late 1940s through the early 1960s. The analysis centers primarily on two wealthy and eccentric entrepreneurs, Roger Babson and Agnew Bahnson, and their efforts to galvanize the study of gravitation. Not...

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  • 2019 Oct 22

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Shane Davis (University of Virginia)

    Title: Solving the Quasar "Crisis"

    Abstract: Observational constraints on the spectral shape and the sizes of quasar emission regions are in conflict with standard accretion disk models. This contrasts with disk dominated states of X-ray binaries, which seem to be reasonably consistent with theoretical predictions. This difference motivates focusing on aspects of the accretion flow that differ between these two systems and one possibility is the ultraviolet...

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  • 2019 Oct 15

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Elena Giorgi (Princeton University)

    Title: On the stability of black holes in classical GR

    Abstract: The stability of black holes is one of the main open problems in GR, and fits in the broader picture of the "final state conjecture", according to which all asymptotically flat initial data for the
    Einstein equation eventually evolve into a finite number of Kerr solutions. We give an overview of the problem of stability of solutions to the Einstein equation, starting from the Minkowski space to the...

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  • 2019 Oct 08

    BHI Colloquium

    1:30pm to 2:30pm

    Location: 

    BHI Meeting Room

    Kento Yagi (Virginia University)

    Title: Theory-agnostic Tests of Gravity with Gravitational Waves

    Abstract: Compact binary merger events recently discovered by the LIGO and Virgo Collaboration offer us excellent testbeds for probing fundamental physics. In this talk, I will focus on two theory-agnostic ways of probing gravity in the strong- and dynamical-field regime. I will first review the current status with the observed binary black hole merger events. I will then describe how such tests will improve in...

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