Hydrodynamics of ultra-relativistic bubble walls

LEONARDO LEITAO; ARIEL MÉGEVAND

NUCLEAR PHYSICS B

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 905 p. 45 - 72

0550-3213

In cosmological first-order phase transitions, gravitational waves aregenerated by the collisions of bubble walls and by the bulk motions caused inthe fluid. A sizeable signal may result from fast-moving walls. In this work westudy the hydrodynamics associated to the fastest propagation modes, namely,ultra-relativistic detonations and runaway solutions. We compute the energyinjected by the phase transition into the fluid and the energy whichaccumulates in the bubble walls. We provide analytic approximations and fits asfunctions of the net force acting on the wall, which can be readily evaluatedfor specific models. We also study the back-reaction of hydrodynamics on thewall motion, and we discuss the extrapolation of the friction force awayfrom the ultra-relativistic limit. We use these results to estimate thegravitational wave signal from detonations and runaway walls.