The REQUIEM Survey. I. A Search for Extended Lyα Nebular Emission around 31 z > 5.7 Quasars

Emanuele Paolo Farina, Fabrizio Arrigoni-Battaia, Tiago Costa, Fabian Walter, Joseph F. Hennawi, Alyssa B. Drake, Roberto Decarli, Thales A. Gutcke, Chiara Mazzucchelli, Marcel Neeleman, Iskren Georgiev, Anna Christina Eilers, Frederick B. Davies, Eduardo Bañados, Xiaohui Fan, Masafusa Onoue, Jan Torge Schindler, Bram P. Venemans, Feige Wang, Jinyi YangSebastian Rabien, Lorenzo Busoni

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


The discovery of quasars a few hundred megayears after the Big Bang represents a major challenge to our understanding of black holes as well as galaxy formation and evolution. Quasars' luminosity is produced by extreme gas accretion onto black holes, which have already reached masses of M BH > 109 M o&dot; by z ∼ 6. Simultaneously, their host galaxies form hundreds of stars per year, using up gas in the process. To understand which environments are able to sustain the rapid formation of these extreme sources, we started a Very Large Telescope/Multi-Unit Spectroscopic Explorer (MUSE) effort aimed at characterizing the surroundings of a sample of 5.7 < z < 6.6 quasars, which we have dubbed the Reionization Epoch QUasar InvEstigation with MUSE (REQUIEM) survey. We here present results of our searches for extended Lyα halos around the first 31 targets observed as part of this program. Reaching 5σ surface brightness limits of 0.1-1.1 × 10-17 erg s-1 cm-2 arcsec-2 over a 1 arcsec2 aperture, we were able to unveil the presence of 12 Lyα nebulae, eight of which are newly discovered. The detected nebulae show a variety of emission properties and morphologies with luminosities ranging from 8 × 1042 to 2 × 1044 erg s-1, FWHMs between 300 and 1700 km s-1, sizes <30 pkpc, and redshifts consistent with those of the quasar host galaxies. As the first statistical and homogeneous investigation of the circumgalactic medium of massive galaxies at the end of the reionization epoch, the REQUIEM survey enables the study of the evolution of the cool gas surrounding quasars in the first 3 Gyr of the universe. A comparison with the extended Lyα emission observed around bright (M1450 ≲ -25 mag) quasars at intermediate redshift indicates little variations on the properties of the cool gas from z ∼ 6 to z ∼ 3, followed by a decline in the average surface brightness down to z ∼ 2.

Original languageEnglish (US)
Article number196
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 20 2019

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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  • REQUIEM survey. I. Ly{alpha} halos around QSOs

    Farina, E. P. (Creator), Arrigoni-Battaia, F. (Creator), Costa, T. (Creator), Walter, F. (Creator), Hennawi, J. F. (Creator), Drake, A. B. (Creator), Decarli, R. (Creator), Gutcke, T. A. (Creator), Mazzucchelli, C. (Creator), Neeleman, M. (Creator), Georgiev, I. (Creator), Eilers, A. (Creator), Davies, F. B. (Creator), Fan, X. (Creator), Onoue, M. (Creator), Schindler, J. (Creator), Venemans, B. P. (Creator), Wang, F. (Creator), Yang, J. (Creator), Rabien, S. (Creator), Busoni, L. (Creator), Davies, F. B. (Creator), Banados, E. (Creator) & Fan, X. (Creator), Centre de Donnees Strasbourg (CDS), 2021


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