Heavy cosmic strings

We argue that cosmic strings with high winding numbers generally form in first-order gauge symmetry breaking phase transitions, and we demonstrate this using computer simulations. These strings are heavier than single-winding strings and therefore more easily observable. Their cosmological evolution may also be very different.

Figure 1

Time evolution of $⟨{\varphi }^2⟩$ for different cooling rates. The time axis has been rescaled by the cooling rate, so that it is in one-to-one correspondence with the effective temperature.

Figure 2

Bubbles of broken phase at the time when $⟨{\varphi }^2⟩=0.33$ in the simulations with cooling rates (a) $\sigma =2.5\times {10}^{-4}$ and (b) $\sigma =2.5\times {10}^{-5}$. With lower cooling rate, the bubbles are larger and there are fewer of them, because the nucleation rate was lower at the time of their nucleation.

Figure 3

String networks formed in simulations with two different cooling rates $\sigma$. In both cases, we have used a short period of gradient flow to remove short-distance thermal noise, and plotted isosurfaces of $|\varphi |$. We have made movies of the full time evolution available in Ref. 22.