Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
134 tokens/sec
GPT-4o
10 tokens/sec
Gemini 2.5 Pro Pro
47 tokens/sec
o3 Pro
4 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

Energy Budget of Cosmological First-order Phase Transitions (1004.4187v1)

Published 23 Apr 2010 in hep-ph and astro-ph.CO

Abstract: The study of the hydrodynamics of bubble growth in first-order phase transitions is very relevant for electroweak baryogenesis, as the baryon asymmetry depends sensitively on the bubble wall velocity, and also for predicting the size of the gravity wave signal resulting from bubble collisions, which depends on both the bubble wall velocity and the plasma fluid velocity. We perform such study in different bubble expansion regimes, namely deflagrations, detonations, hybrids (steady states) and runaway solutions (accelerating wall), without relying on a specific particle physics model. We compute the efficiency of the transfer of vacuum energy to the bubble wall and the plasma in all regimes. We clarify the condition determining the runaway regime and stress that in most models of strong first-order phase transitions this will modify expectations for the gravity wave signal. Indeed, in this case, most of the kinetic energy is concentrated in the wall and almost no turbulent fluid motions are expected since the surrounding fluid is kept mostly at rest.

Citations (461)

Summary

  • The paper details how bubble wall velocities and dynamic regimes like detonations and deflagrations control the energy distribution during phase transitions.
  • It shows that inadequate friction can trigger runaway regimes, accelerating bubble walls to ultra-relativistic speeds and altering gravitational wave signals.
  • The study provides efficiency coefficients for energy transfer that enhance predictions for both baryon asymmetry and gravitational wave observables in the cosmos.

Analysis of Energy Budget in Cosmological First-order Phase Transitions

The paper "Energy Budget of Cosmological First-order Phase Transitions" by Espinosa et al. provides an in-depth examination of the dynamics and energetics associated with first-order cosmological phase transitions. These transitions, pivotal in theoretical physics, notably influence phenomena such as electroweak baryogenesis and the possible generation of a gravitational wave background.

Hydrodynamic Relations and Phase Transition Dynamics

The paper extensively discusses the hydrodynamic treatment required to model bubble growth during these phase transitions. One of the focal points is the determination of bubble wall velocity, an essential factor for predicting both baryon asymmetry and gravitational wave signals. The paper identifies different modes of bubble dynamics - detonations, deflagrations, and hybrids - each characterized by distinct fluid velocity and energy distribution profiles.

The authors compute the efficiency of vacuum energy transfer to the plasma and the bubble wall across these regimes without specifically tying their results to any particular particle physics model. This broad applicability is crucial for understanding phase transitions in diverse cosmological contexts.

Conditions for Runaway Regimes

A significant contribution of this paper is the clarification of the runaway regime, where bubble walls can accelerate to ultra-relativistic speeds. In many strong first-order phase transitions, the friction, typically counteracting wall acceleration, becomes insufficient. In such scenarios, a large portion of the kinetic energy concentrates in the wall rather than causing turbulent fluid motion, leading to distinctive predictions for gravitational wave signals—a facet that contradicts the expectations set by the Chapman-Jouguet condition often applied in earlier studies.

Implications and Future Directions

The paper highlights that most strong first-order models deviate from conventional expectations of gravitational wave signals due to these runaway dynamics. It implies that the emitted gravitational wave spectrum strongly depends on how the energy divides between plasma motions and wall acceleration, which is contingent upon the interaction specifics within the underlying particle physics model.

Future research might focus on integrating detailed particle physics interactions into these models. Such advancement could refine predictions about gravitational waves or baryon asymmetry, especially as observational cosmology inches towards detecting these elusive signals.

In conclusion, this paper advances the theoretical framework to analyze cosmological phase transitions, emphasizing the implications of energy distribution in highly energetic cosmic environments. While providing robust numerical frameworks and efficiency coefficients indispensable for practical calculations, it also sets the grounds for further exploration into the seamless integration of phase transition dynamics with emerging astrophysical data.