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

M. Maseda, R. Bacon, M. Franx, J. Brinchmann, J. Schaye, L. A. Boogaard, N. Bouchť, R. Bouwens, S. Cantalupo, T. Contini, T. Hashimoto, H. Inami, R. A. Marino, S. Muzahid, T. Nanayakkara, J. Richard, K. B. Schmidt, A. Verhamme, L. Wisotzki

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 mAB ≳ 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 1216Å breaks and faint ultraviolet continua (MUV∼-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.

galaxies: evolution, galaxies: high-redshift, quasars: emission lines

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.

The Astrophysical Journal Letters
Volume 865, Number 1
2018 September

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Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia