The D-material universe

TL;DR

This paper explores a brane world model with D-particle defects that can mimic dark matter, influence galaxy lensing, and induce cosmic inflation through D-particle recoil velocity condensates, connecting early universe inflation to large-scale structure growth.

Contribution

It extends previous work by analyzing D-particle recoil effects as dark matter mimics, presenting lensing phenomenology, and proposing a D-particle driven inflation mechanism linked to string theory parameters.

Findings

D-particle recoil velocities can mimic dark matter in galaxies.

The model aligns with galaxy lensing data that challenge modified gravity theories.

Inflation can be driven by D-particle condensates under certain string scale and brane tension conditions.

Abstract

In a previous publication by some of the authors (N.E.M., M.S. and M.F.Y.), we have argued that the "D-material universe", that is a model of a brane world propagating in a higher-dimensional bulk populated by collections of D-particle stringy defects, provides a model for the growth of large-scale structure in the universe via the vector field in its spectrum. The latter corresponds to D-particle recoil velocity excitations as a result of the interactions of the defects with stringy matter and radiation on the brane world. In this article, we first elaborate further on the results of the previous study on the galactic growth era and analyse the circumstances under which the D-particle recoil velocity fluid may "mimic" dark matter in galaxies. A lensing phenomenology is also presented for some samples of galaxies, which previously were known to provide tension for modified gravity (TeVeS) models. The current model is found in agreement with these lensing data. Then we discuss a cosmic evolution for the D-material universe by analysing the conditions under which the late eras of this universe associated with large-scale structure are connected to early epochs, where inflation takes place. It is shown that inflation is induced by dense populations of D-particles in the early universe, with the role of the inflaton field played by the condensate of the D-particle recoil-velocity fields under their interaction with relativistic stringy matter, only for sufficiently large brane tensions and low string mass scales compared to the Hubble scale. On the other hand, for large string scales, where the recoil-velocity condensate fields are weak, inflation cannot be driven by the D-particle defects alone. In such cases inflation may be driven by dilaton (or other moduli) fields in the underlying string theory.