A Multiwavelength Study of ELAN Environments (AMUSE2). Mass Budget, Satellites Spin Alignment, and Gas Infall in a Massive z 3 Quasar Host Halo

The systematic targeting of extended Lyα emission around high-redshift quasars resulted in the discovery of rare and bright Enormous Lyα Nebulae (ELANe) associated with multiple active galactic nuclei (AGNs). We initiate here "a multiwavelength study of ELAN environments" (AMUSE²) focusing on the ELAN around the z ~ 3 quasar SDSS J1040+1020, aka the Fabulous ELAN. We report on VLT/HAWK-I, APEX/LABOCA, JCMT/SCUBA-2, SMA/850μm, and ALMA CO(5-4), and 2 mm observations and compare them to previously published VLT/MUSE data. The continuum and line detections enable a first estimate of the star formation rates, dust, stellar, and molecular gas masses in four objects associated with the ELAN (three AGNs and one Lyα emitter), confirming that the quasar host is the most star-forming (star formation rate of ~500 M _⊙ yr^-1) and massive galaxy (M _star ~ 10¹¹ M _⊙) in the system, and thus can be assumed as central. All four embedded objects have similar molecular gas reservoirs ( ${M}_{{{\rm{H}}}_{2}}\sim {10}^{10}$ M _⊙), resulting in short depletion timescales. This fact together with the estimated total dark matter halo mass, M _DM = (0.8-2) × 10¹³ M _⊙, imply that this ELAN will evolve into a giant elliptical galaxy. Consistently, the constraint on the baryonic mass budget for the whole system indicates that the majority of baryons should reside in a massive warm/hot reservoir (up to 10¹² M _⊙), needed to complete the baryons count. Additionally, we discuss signatures of gas infall on the compact objects as traced by Lyα radiative transfer effects and the evidence for the alignment between the satellites' spins and their directions to the central.