An Alternative Hubble parameter: Explaining DESI data and High redshift Supermassive Black Hole

TL;DR

This paper proposes a novel cosmological model with multiple non-comoving fluids to explain DESI data and early supermassive black holes, aligning well with observations and providing a new timeline for SMBH formation.

Contribution

It introduces a mixed fluid FLRW model with non-comoving frames to address high-redshift observations and SMBH formation timelines, extending standard cosmology.

Findings

Hubble parameter matches DESI DR2 and Cosmic Chronometers data up to z<2.33

Model accommodates early SMBH formation timelines

Consistent with CMB acoustic scale constraints

Abstract

Phantom dark energy from DESI DR2 BAO [1]-[3] and bservations of Supermassive Black Hole (SMBH) at very high redshift present two new challenges in cosmology and astrophysics. In this work, we show that both problems can be addressed by considering the possibility that any single cosmic background fluid is described by a FLRW metric with its own comoving frame, but these frames are relatively non-comoving with one another. This idea is used to model the peculiar velocities of galaxies. In Lemaitre-Tolman formulation, a solution for a particle's free fall velocity in this mixed fluid is given by adding free fall velocities due to individual fluid components. We find that the Hubble parameter in this model is consistent with Cosmic Chronometers (CC) and DESI DR2 data upto z<2.33, while matching the observed CMB acoustic angular scale constraint. We use this new solution to examine the SMBH formation timeline and find that the lapse between redshifts increases and provides sufficient cosmological time for the formation of SMBHs at high redshifts.t