High-definition imaging of a filamentary connection between a close quasar pair at z=3

TL;DR

This paper reports the first high-definition imaging of a filamentary cosmic web structure connecting two quasar-host galaxies at redshift 3.22, providing insights into the morphology and density of intergalactic filaments predicted by dark matter theories.

Contribution

It presents the first direct detection and detailed imaging of a cosmic web filament in emission at high redshift, validating dark matter model predictions.

Findings

Detection of a filament connecting two quasars at z~3.22

Characterization of filament morphology and surface brightness profiles

Validation of filament density predictions from simulations

Abstract

Filaments connecting halos are a long-standing prediction of cold dark matter theories. We present a detection of the cosmic web emission connecting two quasar-host galaxies at redshift z ~3.22 in the MUSE Ultra Deep Field (MUDF). The very deep observations unlock a high-definition view of the filament morphology, a measure of the transition radius between the intergalactic and circumgalactic medium, and the characterization of the surface brightness profiles along the filament and in the transverse direction. Through systematic comparisons with simulations, we validate the filaments' typical density predicted in the current cold dark-matter model. Our analysis of the MUDF field, an excellent laboratory for quantitatively studying filaments in emission, opens a new avenue to constrain the physical properties of the cosmic web and to trace the distribution of dark matter on large scales.