Understand
Since the energy momentum tensor of a magnetic field always contains a spin-2 component in its anisotropic stress, stochastic primordial magnetic field (PMF) in the early universe must generate stochastic gravitational wave (GW) background.
- This process will greatly affect the relic gravitational wave (RGW), which is one of major scientific goals of the laser interferometer GW detections.
- Recently, the fifth science (S5) run of laser interferometer gravitational-wave observatory (LIGO) gave a latest upper limit $\Omega_{GW}<6.9\times10^{-6}$ on the RGW background.
- Utilizing this upper limit, we derive new PMF Limits: for a scale of galactic cluster $\lambda=1$ Mpc, the amplitude of PMF, that produced by the electroweak phase transition (EPT), has to be weaker than $B_{\lambda} \leq 4\times 10^{-7}$ Gauss; for a scale of supercluster $\lambda=100$ Mpc, the amplitude of PMF has to be weaker than $B_{\lambda} \leq 9\times 10^{-11}$ Gauss.
Reading the bibliography…