MUSE Spectroscopic Identifications of Ultra-faint Emission Line Galaxies with M_UV ∼ −15

Michael V Maseda , Roland Bacon (1) , Marijn Franx , Jarle Brinchmann (2) , Joop Schaye (2) , Leindert Boogaard (2) , Nicolas Bouche , Rychard J Bouwens , Sebastiano Cantalupo (3) , Thierry Contini (4) , Takuya Hashimoto , Hanae Inami (1) , Raffaella A Marino , Sowgat Muzahid , Themiya Nanayakkara , Johan Richard , Kasper B Schmidt , Anne Verhamme , Lutz Wisotzki

1 CRAL - Centre de Recherche Astrophysique de Lyon
2 Leiden Observatory [Leiden]
3 D-INFK - Department of Computer Science [ETH Zürich]
4 IRAP - Institut de recherche en astrophysique et planétologie

Using an ultra-deep blind survey with the MUSE integral field spectrograph on the European Southern Observatory Very Large Telescope, we obtain spectroscopic redshifts to a depth never before explored: galaxies with observed magnitudes m AB 30-32. Specifically, we detect objects via Lyα emission at 2.9<z<6.7 without individual continuum counterparts in areas covered by the deepest optical/near-infrared imaging taken by the Hubble Space Telescope, the Hubble Ultra Deep Field. In total, we find 102 such objects in 9 square arcminutes at these redshifts. Detailed stacking analyses confirm the Lyα emission as well as the 1216 Å breaks and faint ultraviolet continua (M UV ∼−15). This makes them the faintest spectroscopically confirmed objects at these redshifts, similar to the sources believed to reionize the universe. A simple model for the expected fraction of detected/undetected Lyα emitters as a function of luminosity is consistent with these objects being the high-equivalent width tail of the normal Lyα-emitter population at these redshifts.

Domaines: Astrophysique [astro-ph]

Michael V Maseda, Roland Bacon, Marijn Franx, Jarle Brinchmann, Joop Schaye, et al.. MUSE Spectroscopic Identifications of Ultra-faint Emission Line Galaxies with M_UV ∼ −15. The Astrophysical journal letters, 2018, 865 (1), pp.L1. ⟨10.3847/2041-8213/aade4b⟩. ⟨hal-02325247⟩