Gravitational waves from holographic first-order QCD phase transition with magnetic field

TL;DR

This study explores gravitational wave signals generated by a first-order QCD phase transition influenced by magnetic fields, using holographic models to predict observable spectra for future gravitational wave detectors.

Contribution

It introduces a holographic framework to analyze magnetic field effects on gravitational waves from QCD phase transitions, including spectral predictions for various bubble dynamics.

Findings

Magnetic fields shift GW spectral peaks to lower frequencies.

Sound waves dominate GW signals near the spectral peak.

Bubble collisions are significant at spectral edges.

Abstract

In this paper, we investigate the generation of gravitational waves (GWs) from a first-order QCD confinement-deconfinement phase transition under external magnetic field from holography. We analyze the GWs spectra across both hard wall and soft wall models for Jouguet detonations and non-runaway scenarios. Our results indicate that increasing the magnetic field shifts the spectral peak to lower frequencies. The predicted GWs signals are potentially detectable by observatories such as IPTA, SKA, BBO and NANOGrav. Decomposing the spectra reveals that sound waves typically dominate the signal around the peak frequency, bubble collisions prevail at spectral extremities, and the contribution from MHD turbulence is significant only for non-runaway bubble scenarios at high frequencies. This work suggests that magnetized QCD phase transitions are viable cosmological sources for observable GW backgrounds, offering a potential pathway to constrain primordial magnetic fields through future PTA observations.