Feebly Self-Interacting Cold Dark Matter: New theory for the Core-Halo structure in GLSB Galaxies

TL;DR

This paper proposes a new model for feebly self-interacting cold dark matter that explains the core-halo structure in LSB galaxies and relates CMB anisotropies to dark matter perturbations during early universe epochs.

Contribution

It introduces a novel theoretical framework for feebly self-interacting cold dark matter, linking galaxy rotation curves and CMB anisotropies with perturbation growth.

Findings

Relation between CMB oscillations and baryon-radiation plasma ejection velocity

Expression for growth of dark matter perturbations consistent with standard theory at late epochs

Impact of dark matter potential perturbations on CMB temperature anisotropy

Abstract

We explore the low energy cosmological dynamics of feebly self-interacting cold dark matter and propose a new simple explanation for the rotation curves of the core-halo model in massive LSB (Low Surface brightness)galaxies. We argue in favor of the truly collisionless nature of cold dark matter,which is feebly,self-interacting at small scales between epochs of equality and recombination.For this, we assume a model, wherein strongly coupled baryon-radiation plasma ejects out of small regions of concentrated cold dark matter without losing its equilibrium. We use the Merscerskii equation i.e. the variable mass formalism of classical dynamics.We obtain new results relating the oscillations in the CMB anisotropy to the ejection velocity of the baryon-radiation plasma,which can be useful tool for numerical work for exploring the second peak of CMB. Based on this model, we discuss the growth of perturbations in such a feebly self-interacting,cold dark matter both in the Jeans theory and in the expanding universe using Newton's theory.We obtain an expression for the growth of fractional perturbations in cold dark matter,which reduce to the standard result of perturbation theory for late recombination epochs. We see the effect of the average of the perturbations in the cold dark matter potential on the cosmic microwave background temperature anisotropy that originated at redshifts between equality and recombination i.e. 1100 < z < z_{eq}. Also we obtain an expression for the Sachs-Wolfe effect,i.e. the CMB temperature anisotropy at decoupling in terms of the average of the perturbations in cold dark matter potential.