Properties of Central Regions of the Dark Matter Halos in the Model with a Bump in the Power Spectrum of Density Perturbations

TL;DR

This study investigates how a bump in the primordial power spectrum influences the properties and survival of early compact dark matter halos, with implications for galaxy formation and observations.

Contribution

It demonstrates that a bump in the power spectrum leads to denser, more resilient early galaxies that can survive to the present day, a novel insight into galaxy evolution.

Findings

Galaxies from the bump region are denser and more compact.

These galaxies are less affected by tidal disruption.

Some survive to the current epoch, influencing galaxy outskirts.

Abstract

A surprisingly large number of galaxies with masses of $\sim10^9-10^{10}M_\odot$ at redshifts of $z\geq9$ are discovered with the James Webb Space Telescope. A possible explanation for the increase in the mass function can be the presence of a local maximum (bump) in the power spectrum of density perturbations on the corresponding scale. In this paper, it is shown that simultaneously with the growth of the mass function, galaxies from the bump region must have a higher density (compactness) compared to cosmological models without a bump. These more compact galaxies have been partially included in larger galaxies and have been subjected to tidal gravitational disruption. They have been less destructed than ``ordinary'' galaxies of the same mass, and some of them could survive to $z = 0$ and persist on the periphery of some galaxies. The formation and evolution of compact halos in a cube with a volume of $(47 \,\text{Mpc})^3$ with $(1024)^3$ dark matter particles in the redshift range from 120 to 0 have been numerically simulated and observational implications of the presence of such galaxies in the current Universe have been discussed.