Gravitational waves from vacuum first order phase transitions II: from thin to thick walls. (arXiv:2005.13537v1 [astro-ph.CO])

Gravitational waves from vacuum first order phase transitions II: from thin to thick walls. (arXiv:2005.13537v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Cutting_D/0/1/0/all/0/1">Daniel Cutting</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Escartin_E/0/1/0/all/0/1">Elba Granados Escartin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hindmarsh_M/0/1/0/all/0/1">Mark Hindmarsh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weir_D/0/1/0/all/0/1">David J. Weir</a>

In a vacuum first order phase transition gravitational waves are generated
from collision of bubbles of the true vacuum. The spectrum from such collisions
takes the form of a broken power law. We consider a toy model for such a phase
transition where the dynamics of the scalar field depends on a single parameter
$bar{lambda}$, which controls how thin the bubble wall is at nucleation and
how close to degenerate the vacua are relative to the barrier. We extend on our
previous work by performing a series of simulations with a range of
$bar{lambda}$. The peak of the gravitational wave power spectrum varies by up
to a factor of $1.3$, which is probably an unobservable effect. We find that
the ultraviolet (UV) power law in the gravitational wave spectrum becomes
steeper as $bar{lambda} rightarrow 0$, varying between $k^{-1.4}$ and
$k^{-2.3}$ for the $bar{lambda}$ considered. This provides some evidence that
the form of the underlying effective potential of a vacuum first order phase
transition could be determined from the gravitational wave spectrum it
produces.

In a vacuum first order phase transition gravitational waves are generated
from collision of bubbles of the true vacuum. The spectrum from such collisions
takes the form of a broken power law. We consider a toy model for such a phase
transition where the dynamics of the scalar field depends on a single parameter
$bar{lambda}$, which controls how thin the bubble wall is at nucleation and
how close to degenerate the vacua are relative to the barrier. We extend on our
previous work by performing a series of simulations with a range of
$bar{lambda}$. The peak of the gravitational wave power spectrum varies by up
to a factor of $1.3$, which is probably an unobservable effect. We find that
the ultraviolet (UV) power law in the gravitational wave spectrum becomes
steeper as $bar{lambda} rightarrow 0$, varying between $k^{-1.4}$ and
$k^{-2.3}$ for the $bar{lambda}$ considered. This provides some evidence that
the form of the underlying effective potential of a vacuum first order phase
transition could be determined from the gravitational wave spectrum it
produces.

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