Early Structure Formation from Cosmic String Loops in Light of Early JWST Observations

Abstract: Cosmic strings, if they exist, source nonlinear and non-Gaussian perturbations all the way back to the time of equal matter and radiation (and earlier). Here, we compute the mass function of halos seeded by a scaling distribution of cosmic string loops, and we compare the results with the predictions of the standard Gaussian $\Lambda$CDM model. Assuming a simple linear relation between stellar mass and halo mass, we also compute the stellar mass function. The contribution of cosmic strings dominates at sufficiently high redshifts $z > z_c$ where $z_c$ depends on the mass of the halo and on the mass per unit length $\mu$ of the strings and is of the order $z_c \sim 12$ for $G\mu = 10^{-8}$. We find that strings with this value of $G\mu$ can explain the preliminary JWST data on the high redshift stellar mass density. Based on an extreme value statistic, we find that the mass of the heaviest expected string-seeded galaxy for the current JWST sky coverage is compatible with the heaviest detected galaxy. Given the uncertainties in the interpretation of the JWST data, we discuss predictions for higher redshift observations.