A VLT/MUSE analysis of HeIIλ1640 emitters at z = 2 – 4. Issue Volume 15:Issue S352(2019) (June 2019)

• Record Type: Journal Article
• Authors: Nanayakkara, Themiya
• Editors: da Cunha, Elisabete; Hodge, Jacqueline; Afonso, José; Pentericci, Laura; Sobral, David
• Is Part Of: Proceedings of the International Astronomical Union. Volume 15:Issue S352(2019)
• Page Start: 78
• Page End: 78
• Publication Date: 2019-06
• Subjects: Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S1743921320001143
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: In the quest to study early star-formation physics in the universe, one of the most sought after tracers is HeIIλ1640, with its presence in the lack of other metal emission/absorption lines generally being interpreted as evidence for metal-poor stellar populations. HeII ionizing photons are produced via sources of hard ionizing radiation and requires photons with energies ⩾ 54.4eV, however, traditional stellar population models lack sufficient ionising photons to match with current observations. Our analysis of z = 2 – 4 HeIIλ1640 emitters from deep 10-30h pointings from MUSE has shown that ISM properties inferred from multiple rest-UV diagnostics are not compatible with requirements necessary to reproduce HeIIλ1640 equivalent-widths. Thus, we have used latest generation of single, rotational, and binary stellar population models with realistic dust physics to explore rest-UV emission line diagnostics and link with H and He + ionisation photon production efficiencies (ξion (H, He + )) in a variety of stellar/gas metallicities and star-formation histories. I will discus our latest results and show that including 'exotic' stellar phenomena such as extreme low-metallicity binary stars, X-ray binaries, and dust dissociation physics may be necessary to lessen the tension between models and observations.