Gravitational waves from deflagration bubbles in first-order phase transitions

The walls of bubbles in a first-order phase transition can propagate either as detonations, with a velocity larger than the speed of sound, or deflagrations, which are subsonic. We calculate the gravitational radiation that is produced by turbulence during a phase transition which develops via deflagration bubbles. We take into account the fact that a deflagration wall is preceded by a shock front which distributes the latent heat throughout space and influences other bubbles. We show that turbulence can induce peak values of Omega(GW) as high as similar to 10(-9). We discuss the possibility of detecting at LISA (Laser Interferometer Space Antennae) gravitational waves produced in the electroweak phase transition with wall velocities v(w)less than or similar to 10(-1), which favor electroweak baryogenesis.