The Baryonic and Dark Matter Properties of High Redshift Gravitationally Lensed Disk Galaxies

TL;DR

This study analyzes four gravitationally lensed disk galaxies at redshift 1, revealing their dark matter and stellar properties, and suggesting disk growth through angular momentum conserving accretion over cosmic time.

Contribution

It provides detailed modeling of high-redshift disk galaxies, comparing their dark matter and stellar properties to local galaxies, and supports a gradual disk formation scenario.

Findings

High redshift disks have larger dark matter densities than local counterparts.

Stellar masses in z=1 disks are smaller than similar local galaxies.

Angular momentum per unit mass remains consistent from z=1 to present.

Abstract

We present a detailed study of the structural properties of four gravitationally lensed disk galaxies at z=1. Modelling the rotation curves on sub-kpc scales we derive the values for the disk mass, the reference dark matter density and core radius, and the angular momentum per unit mass. The derived models suggest that the rotation curve profile and amplitude are best fit with a dark matter component similar to those of local spiral galaxies. The stellar component also has a similar length scale, but with substantially smaller masses than similarly luminous disk galaxies in the local universe. Comparing the average dark matter density inside the optical radius we find that the disk galaxies at z=1 have larger densities (by up to a factor of 7) than similar disk galaxies in the local Universe. Furthermore, the angular momentum per unit mass versus reference velocity is well matched to the local relation, suggesting that the angular momentum of the disk remains constant between high redshifts and the present day. Though statistically limited, these observations point towards a spirals' formation scenario in which stellar disks are slowly grown by the accretion of angular momentum conserving material.