Disc scalelengths out to redshift 5.8

TL;DR

This study measures the exponential disc scalelength of 686 galaxies up to redshift 5.8, revealing a significant decrease in size at high redshift compared to local galaxies, challenging existing cosmological models.

Contribution

It provides the first large-scale measurement of disc scalelengths at high redshift, showing a greater size evolution than predicted by current cosmological theories.

Findings

Disc scalelengths decrease by up to a factor of 8 at high redshift.

Exponential disc component dominates galaxy structure out to redshift 5.8.

Observed size evolution exceeds theoretical predictions.

Abstract

We compute the exponential disc scalelength for 686 disc galaxies with spectroscopic redshifts out to redshift 5.8 based on Hubble Space Telescope archival data. We compare the results with our previous measurements based on 30000 nearby galaxies from the Sloan Digital Sky Survey. Our results confirm the presence of a dominating exponential component in galaxies out to this redshift. At the highest redshifts, the disc scalelength for the brightest galaxies with absolute magnitude between -24 and -22 is up to a factor 8 smaller compared to that in the local Universe. This observed scalelength decrease is significantly greater than the value predicted by a cosmological picture in which baryonic disc scalelength scales with the virial radius of the dark matter halo.