Joint Condensed Matter and Gravitation Theory Seminar
Thursday, October 12, 2000, 2 p.m.
Plant Sciences Building, Room 1130
Sonic Pulses from Crossed Vortices in Liquid
4He: A Simulation
of High-Energy Radiation from Crossed Cosmic Strings
(Department of Physics, University of Maryland)
Abstract: The crossing and recombination of a pair of cosmic
strings provides a plausible explanation for the extremely high amount
of energy that is observed in gamma ray bursts. Cosmic strings are
hypothesized remnants that are expected inevitably to be left over from
the phase transition that must have taken place in the early universe.
We are proposing, as an analogue that can be studied in the laboratory,
an experiment to detect the crossing and recombination of a pair of vortices
in superfluid 4He. Like the cosmic strings, these are
topological singularities with surplus trapped energy stored in their cores.
Although nominally metastable, such a singularity is an excited state of
the system that has robust stability until it is triggered to release its
energy of excitation by an the encounter with a second singularity.
These energy bursts will generate pressure pulses detectable by suitable
instrumentation. A simple model yield a characteristic time signature
for the sonic pulses that should enable their unambiguous identification.
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