Astrophysics Seminars

I will present a novel screening mechanism that allows a scalar field to mediate a long range ~Mpc force of gravitational strength in the cosmos while satisfying local tests of gravity. The mechanism hinges on local symmetry restoration in the...

The idea that peaks in the initial density fluctuation field may be important at later times has been a sort of guiding principle in most models of hierarchical structure formation for about three decades. I will discuss whether the qualitative...

Data from cosmic ray experiments have suggested the need for new, primary sources of cosmic rays. I will review the status of the anomalies and some of the models to explain them, including those models with dark forces. We'll discuss the near-term...

The first potentially habitable exoplanets will likely be discovered in the next two years, but they will be much fainter than their host stars, so these worlds will at first be studied indirectly. Fortunately, the existence of short-period giant...

The discovery of more than 400 extrasolar planets keeps challenging the theory of planet formation. Multi-planetary systems are of particular interest. Their orbital parameters allow us to constrain properties of the otherwise unobservable formation...

Quasars and radio galaxies display great morphological variety that correlates with other properties such as spectral slope and luminosity. The unification theory for radio-loud active galactic nuclei (AGNs) attempts to explain much of this...