The MUSE Hubble Ultra Deep Field Survey

• Published in: Astronomy and astrophysics (Berlin) 2017-12, Vol.608
• Main Authors: Maseda, Michael V., Brinchmann, Jarle, Franx, Marijn, Bacon, Roland, Bouwens, Rychard J., Schmidt, Kasper B., Boogaard, Leindert A., Contini, Thierry, Feltre, Anna, Inami, Hanae, Kollatschny, Wolfram, Marino, Raffaella A., Richard, Johan, Verhamme, Anne, Wisotzki, Lutz
• Format: Article
• Language: English
• Subjects: Attenuation; Cosmic dust; Emissions; Equivalence; Galaxies; galaxies: evolution; galaxies: high-redshift; Hubble deep field; Integral field spectroscopy; Intergalactic media; intergalactic medium; Population (statistical); Red shift; Rest; Spectroscopy; Spectrum analysis; Star & galaxy formation; Star formation; Stellar age
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201730985

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.