The MUSE Hubble Ultra Deep Field Survey

Michael V. Maseda (1) , Jarle Brinchmann (1, 2) , Marijn Franx (1) , Roland Bacon (3) , Rychard J. Bouwens (1) , Kasper B. Schmidt (4) , Leindert A. Boogaard (1) , Thierry Contini (5) , Anna Feltre (3) , Hanae Inami (3) , Wolfram Kollatschny (6) , Raffaella A. Marino (7) , Johan Richard (3) , Anne Verhamme (3, 8) , Lutz Wisotzki (4)

1 Universiteit Leiden = Leiden University
2 Universidade do Porto = University of Porto
3 CRAL - Centre de Recherche Astrophysique de Lyon
4 AIP - Leibniz-Institut für Astrophysik Potsdam
5 IRAP - Institut de recherche en astrophysique et planétologie
6 Georg-August-University = Georg-August-Universität Göttingen
7 Institute of Astronomy [ETH Zürich]
8 ObsGE - Observatoire Astronomique de l'Université de Genève

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 ~ 7 × 10-18 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] λ5007, finding a strong correlation between the two. Down to the flux limits that we observe (~ 1 × 10-18 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.

Mots clés: galaxies: high-redshift; intergalactic medium; galaxies: evolution

Domaines: Astrophysique [astro-ph]

Michael V. Maseda, Jarle Brinchmann, Marijn Franx, Roland Bacon, Rychard J. Bouwens, et al.. The MUSE Hubble Ultra Deep Field Survey: IV. Global properties of C III] emitters. Astronomy and Astrophysics - A&A, 2017, 608, pp.A4. ⟨10.1051/0004-6361/201730985⟩. ⟨hal-02959103⟩