2017/09/24 by Fabrizio Arrigoni Battaia, J. Xavier Prochaska, Joseph F. Hennawi +5 · 1 citation
Physics and Astronomy · #astro-ph.GA #astro-ph.CO
paper · pdf · doi:10.1093/mnras/stx2465
39 pages with 27 figures and 5 appendices. Accepted to MNRAS
arxiv created 2017/09/24 · arxiv updated 2017/12/06
In an effort to search for Lyα emission from circum- and intergalactic gas on scales of hundreds of kpc around z∼3 quasars, and thus characterise the physical properties of the gas in emission, we have initiated an extensive fast-survey with the Multi Unit Spectroscopic Explorer (MUSE): Quasar Snapshot Observations with MUse: Search for Extended Ultraviolet eMission (QSO MUSEUM). In this work, we report the discovery of an enormous Lyα nebula (ELAN) around the quasar SDSS~J102009.99+104002.7 at z=3.164, which we followed-up with deeper MUSE observations. This ELAN spans ∼297 projected kpc, has an average Lyα surface brightness \rm SB\rm Lyα∼ 6.04×10-18 erg s-1 cm-2 arcsec-2 (within the 2σ isophote), and is associated with an additional four, previously unknown embedded sources: two Lyα emitters and two faint active galactic nuclei (one Type-1 and one Type-2 quasar). By mapping at high significance the line-of-sight velocity in the entirety of the observed structure, we unveiled a large-scale coherent rotation-like pattern spanning ∼300 km s-1 with a velocity dispersion of <270 km s-1, which we interpret as a signature of the inspiraling accretion of substructures within the quasar's host halo. Future multiwavelength data will complement our MUSE observations, and are definitely needed to fully characterise such a complex system. None the less, our observations reveal the potential of new sensitive integral-field spectrographs to characterise the dynamical state of diffuse gas on large scales in the young Universe, and thereby witness the assembly of galaxies.