135 research outputs found
Self-gravitating scalar breathers with negative cosmological constant
Breather-type (time-periodic and spatially localized) solutions with
spherical symmetry are investigated in a massless scalar field theory coupled
to Einstein's gravity with cosmological constant in spatial dimensions
imposing anti de Sitter (AdS) asymptotics on space-time. Using a code
constructed with the Kadath library that enables the use of spectral methods,
the phase space of breather solutions is explored in detail for and
. It is found that there are discrete families of solutions indexed by an
integer and by their frequency. Using a time evolution code these AdS breathers
are found to be stable for up to a critical central density, in analogy to
boson stars. Using an analytical perturbative expansion small amplitude
breathers are worked out for arbitrary dimensions .Comment: 24 pages, 13 figures, one figure and references added, version
accepted for Phys. Rev.
Scalar field breathers on anti-de Sitter background
We study spatially localized, time-periodic solutions (breathers) of scalar
field theories with various self-interacting potentials on Anti-de Sitter (AdS)
spacetimes in dimensions. A detailed numerical study of spherically
symmetric configurations in dimensions is carried out, revealing a rich
and complex structure of the phase-space (bifurcations, resonances). Scalar
breather solutions form one-parameter families parametrized by their amplitude,
, while their frequency, , is a
function of the amplitude. The scalar breathers on AdS we find have a small
amplitude limit, tending to the eigenfunctions of the linear Klein-Gordon
operator on AdS. Importantly most of these breathers appear to be generically
stable under time evolution.Comment: 30 pages, 22 figure
Radiation of scalar oscillons in 2 and 3 dimensions
The radiation loss of small-amplitude radially symmetric oscillons
(long-living, spatially localized, time-dependent solutions) in two- and
three-dimensional scalar field theories is computed analytically in the
small-amplitude expansion. The amplitude of the radiation is beyond all orders
in perturbation theory and it is determined using matched asymptotic series
expansions and Borel summation. The general results are illustrated on the case
of the two- and three-dimensional sine-Gordon theory and a two-dimensional
model. The analytic predictions are found to be in good agreement with
the results of numerical simulations of oscillons.Comment: 7 pages, 3 figure
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