Detection of companion galaxies around hot dust-obscured hyper-luminous galaxy W0410-0913

TL;DR

This study detects multiple galaxies around a hyper-luminous, hot dust-obscured galaxy at high redshift, revealing a dense environment but no clear merger signs, challenging some galaxy growth models.

Contribution

It provides the first observational evidence of a dense galaxy environment around W0410-0913 without clear merger signatures, informing galaxy formation theories.

Findings

Detection of 24 Lyman-alpha emitting galaxies within 400 kpc of W0410-0913

W0410-0913 resides in a very dense environment at z=3.631

No clear signs of major mergers affecting the galaxy's growth

Abstract

The phase transition between galaxies and quasars is often identified with the rare population of hyper-luminous, hot dust-obscured galaxies. Galaxy formation models predict these systems to grow via mergers, that can deliver large amounts of gas toward their centers, induce intense bursts of star formation and feed their supermassive black holes. Here we report the detection of 24 galaxies emitting Lyman-alpha emission on projected physical scales of about 400 kpc around the hyper-luminous hot dust-obscured galaxy W0410-0913, at redshift z = 3.631, using Very Large Telescope observations. While this indicates that W0410-0913 evolves in a very dense environment, we do not find clear signs of mergers that could sustain its growth. Data suggest that if mergers occurred, as models expect, these would involve less massive satellites, with only a moderate impact on the internal interstellar medium of W0410-0913, which is sustained by a rotationally-supported fast-rotating molecular disk, as Atacama Large Millimeter Array observations suggest.