Merging Rates of the First Objects and the Formation of First Mini-Filaments in Models with Massive Neutrinos

TL;DR

This paper analytically examines how massive neutrinos influence the formation and merging rates of early cosmic structures like filaments and halos, impacting galaxy formation and early universe evolution.

Contribution

It introduces an analytical framework to evaluate the effect of neutrino mass on the merging rates of first star-forming halos and filaments, revealing significant dependencies on neutrino fraction.

Findings

Halo-to-filament merging rate increases with neutrino mass fraction.

Redshift distribution of filament collapse peaks at z~8.

Formation of second-generation filaments occurs around z~3.

Abstract

We study the effect of massive neutrinos on the formation and evolution of the first filaments containing the first star-forming halos of mass M~10^{6}M_sun at z~20. With the help of the extended Press-Schechter formalism, we evaluate analytically the rates of merging of the first star-forming halos into zero-dimensional larger halos and one-dimensional first filaments. It is shown that as the neutrino mass fraction f_{\nu} increases, the halo-to-filament merging rate increases while the halo-to-halo merging rate decreases sharply. For f_{\nu}<=0.04, the halo-to-filament merging rate is negligibly low at all filament mass scales, while for f_{\nu}>=0.07 the halo-to-filament merging rate exceeds 0.1 at the characteristic filament mass scale of ~10^{9}M_sun. The distribution of the redshifts at which the first filaments ultimately collapse along their longest axes is derived and found to have a sharp maximum at z~8. We also investigate the formation and evolution of the second generation filaments which contain the first galaxies of mass 10^{9}M_sun at z=8 as the parent of the first generation filaments. A similar trend is found: For f_{\nu}>= 0.07 the rate of clustering of the first galaxies into the second-generation filaments exceeds 0.3 at the characteristic mass scale of ~10^{11}M_sun. The longest-axis collapse of these second-generation filaments are found to occur at z~3. The implications of our results on the formation of massive high-z galaxies and the early metal enrichment of the intergalactic media by supernova-driven outflows, and possibility of constraining the neutrino mass from the mass distribution of the high-z central blackholes are discussed.