T. Nanayakkara, J. Brinchmann, MUSE Collaboration
Abstract
Heiiλ1640 emission in the absence of other metal lines is the most sought-after emission line to detect and characterize metal free stellar populations. However, even recent stellar population models with sophisticated treatment of stellar evolution also lack sufficient He+ ionising photons to reproduce observed He 0.1em ii fluxes. We use VLT/MUSE GTO observations to compile a catalogue of 15 z ∼ 2–4 He ii λ1640 emitters from ∼10–30 hour pointings. We show that both He ii λ1640 detections and non-detections occupy similar distribution in UV absolute magnitudes. Rest-UV emission line analysis of our sample shows that the emission lines of our He ii λ1640 emitters are driven by star-formation in solar to moderately sub-solar (∼1/20th) metallicity conditions. However, we find that even after considering effects from binary stars, we are unable to reproduce the He ii λ1640 equivalent widths. Alternative mechanisms are necessary to compensate for the missing He+ ionising photons.
Keywords
galaxies: high-redshift; galaxies: ISM; ultraviolet: ISM
Challenges in Panchromatic Modelling with Next Generation Facilities
Médéric Boquien, Elisabeta Lusso, Carlotta Gruppioni, Patricia Tissera
Cambridge University Press
Proceedings of the International Astronomical Union
Volume 341, Page 235
2020 June
