Strong Gravity News & Events

Abstract: There is considerable interest in the strong-field behavior of Lorentz-violating gravity theories. One point of interest is whether or not the notion of a black hole as an absolute causal boundary persists in these theories, which can sometimes propagate signals infinitely fast. Past work on spherically-symmetric black holes reveal that absolute causal boundaries exist in spite of these infinitely-fast propagating modes. These causal boundaries have come to be known as universal horizons. In this talk, I shall discuss black holes in two popular Lorentz-violating theories, Hořava gravity and Einstein-aether theory, and showcase progress made in exploring their rotating black holes. For Hořava gravity, I shall discuss three-dimensional black holes in its infrared sector. Within this setting, we have derived the most general class of stationary, circularly symmetric, asymptotically anti–de Sitter black hole solutions. I also discuss slowly-rotating black holes in four-dimensional Einstein-aether theory, which we construct numerically. Most notably, we learn from these solutions that universal horizons may not be a generic feature of black holes in Lorentz-violating theories.

Abstract: Sun-like oscillations have been discovered in five hundred main sequence and sub-giant stars and in more than twelve thousand red giant stars in the solar neighbourhood. In this talk, I will argue how this network of natural detectors could be used to probe fundamental physics, including dark matter and gravitational waves. Moreover, these star detectors can complement the experimental research done on Earth. Moreover, this observational network of stars could be used to make other type of gravity tests, as unlike experimental detectors, it should be possible to follow the progression of gravitational waves throughout space. The continuous observation and monitoring of the oscillation spectra of the stars around us, within a sphere of up to one thousand parsecs, could help on the discovery of gravitational waves originating in our Galaxy or even elsewhere in the Universe.

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link to paper