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The MUSE Hubble Ultra Deep Field Survey
IV. Global properties of Cpsp;III] emitters

M. V. Maseda, J. Brinchmann, M. Franx, R. Bacon, R. J. Bouwens, K. B. Schmidt, L. A. Boogaard, T. Contini, A. Feltre, H. Inami, W. Kollatschny, R. A. Marino, J. Richard, A. Verhamme, L. Wisotzki

The C III] λλ1907, 1909 emission doublet has been proposed as an alternative to Lyman-α in redshift confirmations of galaxies at z≳6 since it is not attenuated by the largely neutral intergalactic medium at these redshifts and is believed to be strong in the young, vigorously star-forming galaxies present at these early cosmic times. We present a statistical sample of 17 C III]-emitting galaxies beyond z~1.5 using ~30 h deep VLT/MUSE integral field spectroscopy covering 2 square arcminutes in the Hubble Deep Field South (HDFS) and Ultra Deep Field (UDF), achieving C III] sensitivities of ~2×10-17 erg s-1 cm-2 in the HDFS and ~7x10-18 erg s-1 cm-2 in the UDF. The rest-frame equivalent widths range from 2 to 19 Å. These 17 galaxies represent ~3% of the total sample of galaxies found between 1.5≲z≲4. They also show elevated star formation rates, lower dust attenuation, and younger mass-weighted ages than the general population of galaxies at the same redshifts. Combined with deep slitless grism spectroscopy from the HST/WFC3 in the UDF, we can tie the rest-frame ultraviolet C III] emission to rest-frame optical emission lines, namely [O III]&nbspλ5007, finding a strong correlation between the two. Down to the flux limits that we observe (~1x10-18 erg s-1 cm-2 with the grism data in the UDF), all objects with a rest-frame [O III] λλ4959, 5007 equivalent width in excess of 250 Å, the so-called extreme emission line galaxies, have detections of C III] in our MUSE data. More detailed studies of the C III]-emitting population at these intermediate redshifts will be crucial to understand the physical conditions in galaxies at early cosmic times and to determine the utility of C III] as a redshift tracer.

galaxies: high-redshift / intergalactic medium / galaxies: evolution

Based on observations made with ESO telescopes at the La Silla Paranal Observatory under program IDs 60.A-9100(C), 094.A-2089(B), 095.A-0010(A), 096.A-0045(A), and 096.A-0045(B). This work is also based on observations made with the NASA/ESA Hubble Space Telescope, programs GO-12099 and 12177, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Astronomy & Astrophysics
Volume 608, Article Number A4, Number of pages 16
2017 December

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia