Search Talks

Quantum superpositions of matter are unusually sensitive to decoherence by tiny momentum transfers, in a way that can be made precise with a new diffusion standard quantum limit.  Upcoming matter interferometers will produce unprecedented spatial superpositions of over a million nucleons. What sorts of dark matter scattering events could be seen in these experiments as anomalous decoherence?  We show that it is extremely weak but medium range interaction between matter and dark matter that would be most visible, such as scattering through a Yukawa potential. We construct toy models for these interactions, discuss existing constraints, and delineate the expected sensitivity of forthcoming experiments.  In particular, the OTIMA interferometer developing at the University of Vienna will directly probe many orders of magnitude of parameter space, and the proposed MAQRO satellite experiment would be vastly more sensitive yet.  This is a multidisciplinary talk that will be accessible to a non-specialized audience.

Magnetars are exceptional neutron stars with the highest magnetic
fields ( 10^15 gauss) in the universe, an unusual quasi steady X
radiation (10^35 ergs/sec) and also produce flares which are some of
the brightest events (10^46 ergs in one fifth of a second) to be
recorded. There is no satisfactory model of magnetars.
The talk will cover neutron stars and a new model for the origin of
the magnetic fields in which magnetars arise from a high baryon
density ( phase transition) magnetized core which forms when they are
born. The core magnetic field is initially shielded by the ambient
high conductivity plasma. With time the shielding currents dissipate
transporting the core field out, first to the crust and then breaking
through the crust to the surface of the star. Recent observations
provide support for this model which accounts for several properties
of magnetars and also enables us to identify new magnetars.