Year: 2019
Type: article
Abstract: Deep optical spectroscopic surveys of galaxies provide a unique opportunity to investigate rest-frame ultra-violet (UV) emission line properties of galaxies atz ∼ 2 − 4.5. Here we combine VLT/MUSE Guaranteed Time Observations of theHubbleDeep Field South, Ultra Deep Field, COSMOS, and several quasar fields with other publicly available data from VLT/VIMOS and VLT/FORS2 to construct a catalogue of He II λ1640 emitters atz ≳ 2. The deepest areas of our MUSE pointings reach a 3σline flux limit of 3.1 × 10−19erg s−1cm−2. After discarding broad-line active galactic nuclei, we find 13 He II λ1640 detections from MUSE with a medianMUV = −20.1 and 21 tentative He II λ1640 detections from other public surveys. Excluding Lyα, all except two galaxies in our sample show at least one other rest-UV emission line, with C III]λ1907,λ1909 being the most prominent. We use multi-wavelength data available in theHubblelegacy fields to derive basic galaxy properties of our sample through spectral energy distribution fitting techniques. Taking advantage of the high-quality spectra obtained by MUSE (∼10 − 30 h of exposure time per pointing), we use photo-ionisation models to study the rest-UV emission line diagnostics of the He II λ1640 emitters. Line ratios of our sample can be reproduced by moderately sub-solar photo-ionisation models, however, we find that including effects of binary stars lead to degeneracies in most free parameters. Even after considering extra ionising photons produced by extreme sub-solar metallicity binary stellar models, photo-ionisation models are unable to reproduce rest-frame He II λ1640 equivalent widths (∼0.2 − 10 Å), thus additional mechanisms are necessary in models to match the observed He II λ1640 properties.
Source: Astronomy and Astrophysics
Authors: Themiya Nanayakkara, Jarle Brinchmann, Leindert Boogaard, Rychard Bouwens, Sebastiano Cantalupo, Anna Feltre, Wolfram Kollatschny, Raffaella Anna Marino, Michael Maseda, Jorryt Matthee, Mieke Paalvast, Johan Richard, Anne Verhamme
Institutions: Leiden University, Leiden Observatory, Universidade do Porto, Institute of Astrophysics and Space Sciences, Centro de Astrofísica da Universidade do Porto, ETH Zurich, Centre National de la Recherche Scientifique, Scuola Internazionale Superiore di Studi Avanzati, Centre de Recherche Astrophysique de Lyon, University of Göttingen, University of Geneva
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2913342645