Strong Gravity

This series consists of talks in areas where gravity is the main driver behind interesting or peculiar phenomena, from astrophysics to gravity in higher dimensions.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.


Thursday May 09, 2013

In the last few years several interesting phenomena associated to the interaction between massive black holes and fundamental bosonic fields have been discovered. I present a selection of them, including superradiance instabilities of spin-0, spin-1 and spin-2 fields, floating orbits in extreme-mass ratio inspirals and black-hole spontaneous scalarization. The theoretical potential of these effects
as almost-model-independent smoking guns for exotic particles and modified gravity, as well as their limitations in realistic astrophysical scenarios, are discussed.

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Thursday Apr 25, 2013

The last few years have seen new opportunities for
constraining the physics of neutron star interiors. I will first discuss the
current state of neutron star radius measurements and then go on to discuss
thermal tomography as a probe of the nuclear, magnetic, and transport
properties of neutron star crusts. In each case, I will emphasize the
astrophysics that must be understood to make reliable inferences about the
properties of dense matter from observations of neutron stars.

Scientific Areas: 


Thursday Apr 04, 2013

In the past few years, optical
cooling and manipulating of macroscopic objects, such as micro-mirrors and
cantilevers has developed into an active field of research.
In mechanical systems, the oscillator is attached to its suspension,
a thermal contact that limits the motion isolation. On the other hand, when
these small objects are levitated using the radiation pressure force of lasers,
the excellent thermal isolation even at room temperatures helps produce
very sensitive force detectors, and eventually quantum transducers for quantum

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Tuesday Apr 02, 2013

The bimodality of gamma-ray burst (GRB) durations points
to distinct progenitor classes for the long- and short-duration GRBs. While the
progenitors of long-duration GRBs are now known to be massive stars, the
progenitors of short-duration GRBs remain unidentified. In this talk I will
discuss the discovery of short GRB afterglow and their host galaxies, detailed
studies of their environments from parsec to galactic scales, and studies of
their energetics and beaming. Taken together, these observations point to the

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Thursday Mar 21, 2013

The relativistic wind of pulsars consists of toroidal
stripes of opposite magnetic field polarity, separated by current sheets of hot
plasma. By means of 2D and 3D particle-in-cell simulations, we investigate
particle acceleration and magnetic field dissipation at the termination shock
of a striped pulsar wind. At the shock, the flow compresses and the alternating
fields annihilate by driven magnetic reconnection. Irrespective of the stripe
wavelength "lambda" or the wind magnetization "sigma" (in

Scientific Areas: 


Thursday Mar 14, 2013

The majority of work on asymptotically anti-de Sitter
spacetimes, much of it motivated by the AdS/CFT correspondence, assumes
configurations which are either at or close to equilibrium.

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Thursday Feb 28, 2013

Neutron stars possess the strongest gravitational fields
among stellar objects in the Universe that are not surrounded by a horizon.
This causes the emission from their surfaces to be strongly lensed and
deformed. Two upcoming space X-ray missions, ESA's LOFT and NASA's NICER, aim
to use observations of lightcurves from spinning neutron stars to map their
gravitational fields as well as measure their masses and radii. In this talk, I
will discuss some unexpected strong-field phenomena that affect gravitational

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Thursday Feb 21, 2013

Gamma Rays at 130 GeV and How They Might Come from Dark

I'll discuss the exciting (but somewhat controversial)
new discovery of a sharp gamma ray feature at 130 GeV from near the galactic
center and review some other evidence that might link it to annihilation of
dark matter. I will then explain the challenges in understanding how dark
matter might produce this signal and explain a model or two that overcome these

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Thursday Jan 10, 2013

In the context of holography applied to condensed matter
theory, I will present an analysis of transport properties of p-wave
superfluids by means of a gravity dual. Fluctuations modes in the SU(2)
Einstein-Yang-Mills theory are considered, and phenomenological implications
are derived. Due to the spatial anisotropy of the system, a non-universal shear
viscosity is obtained, along with a new coefficient associated to normal stress
differences. I will also discuss how the transport phenomena in this model is

Scientific Areas: