Gravitational waves from a very strong electroweak phase transition

Abstract

We investigate the production of a stochastic background of gravitational waves in the electroweak phase transition. We consider extensions of the Standard Model which can give very strongly first-order phase transitions, such that the transition fronts either propagate as detonations or run away. To compute the bubble wall velocity, we estimate the friction with the plasma and take into account the hydrodynamics. We track the development of the phase transition up to the percolation time, and we calculate the gravitational wave spectrum generated by bubble collisions, magnetohydrodynamic turbulence, and sound waves. For the kinds of models we consider, we find parameter regions for which the gravitational waves are potentially observable at the planned space-based interferometer eLISA. In such cases, the signal from sound waves is generally dominant, while that from bubble collisions is the least significant of them. Since the sound waves and turbulence mechanisms are diminished for runaway walls, the models with the best prospects of detection at eLISA are those which do not have such solutions. In particular, we find that heavy extra bosons provide stronger gravitational wave signals than tree-level terms. *

Gravitational waves from a supercooled electroweak phase transition and their detection with pulsar timing arrays

“…According to numerical simulations performed with spheres of equal size, percolation occurs when approximately 29% of space is covered by bubbles [51]. As suggested by [15,16], we thus define t p from the condition p(t p ) ≈ 0.7.…”

“…This motivated a series of investigations into the production of GWs in various BSM models, see e.g. [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The characteristic frequency and amplitude of the spectrum are derived from the dynamics of the PT and depend on a few key parameters: the duration of the transition, the size of colliding bubbles, the bubble-walls velocity and the fraction of vacuum energy transferred into the bubble walls.…”

Chiral magnetohydrodynamic turbulence

“…Indeed, a large class of models trying to explain the observed magnetic fields assumes that they have a cosmological origin [8][9][10][11]. It also seems plausible to characterize the early universe by a non-vanishing velocity field, coming from potential first-order phase transitions [12][13][14][15][16] or density perturbations [17]. It then follows that MHD turbulence could be an important phenomenon not only in astrophysical, but also in the cosmological context.…”

Leptophilic dark matter from gauged lepton number: phenomenology and gravitational wave signatures

“…In the following we will briefly review the relevant parameters and the calculation of the GW spectrum, and explain how we evaluate the detectability of the resulting spectra. See [88,[95][96][97] for some recent, more comprehensive reviews. The corresponding results are presented in section 6.4.…”