MUSE Spectroscopic Identifications of Ultra-faint Emission Line Galaxies with M UV ∼ -15
Bacon, Roland; Bouché, Nicolas; Inami, Hanae; Boogaard, Leindert A.; Brinchmann, Jarle; Contini, Thierry; Marino, Raffaella A.; Maseda, Michael V.; Richard, Johan; Schmidt, Kasper B.; Verhamme, Anne; Franx, Marijn; Nanayakkara, Themiya; Hashimoto, Takuya; Bouwens, Rychard J.; Wisotzki, Lutz; Cantalupo, Sebastiano; Schaye, Joop; Muzahid, Sowgat
Netherlands, France, Portugal, Switzerland, Japan, Germany
Abstract
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.
Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program IDs 094.A-2089(B), 095.A-0010(A), 096.A-0045(A), and 096.A-0045(B); and based on data obtained with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.