Predicting the observability of population III stars with ELT-HARMONI via the helium 1640 Å emission line

Kearn Grisdale, Niranjan Thatte, Julien Devriendt, Miguel Pereira-Santaella, Adrianne Slyz, Taysun Kimm, Yohan Dubois, Sukyoung K. Yi

Research output: Contribution to journalArticlepeer-review

Abstract

Population III (Pop. III) stars, as of yet, have not been detected, however as we move into the era of extremely large telescopes this is likely to change. One likely tracer for Pop. III stars is the He iiλ1640 emission line, which will be detectable by the HARMONI spectrograph on the European Extremely Large Telescope (ELT) over a broad range of redshifts (2 ≤ z ≤ 14). By post-processing galaxies from the cosmological, AMR-hydrodynamical simulation newhorizon with theoretical spectral energy distributions (SED) for Pop. III stars and radiative transfer (i.e. the Yggdrasil Models and cloudy look-up tables, respectively) we are able to compute the flux of He iiλ1640 for individual galaxies. From mock 10 h observations of these galaxies we show that HARMONI will be able to detect Pop. III stars in galaxies up to z ∼10 provided Pop. III stars have a top heavy initial mass function (IMF). Furthermore, we find that should Pop. III stars instead have an IMF similar to those of the Pop. I stars, the He iiλ1640 line would only be observable for galaxies with Pop. III stellar masses in excess of $10^{7}\, {\rm M}_\odot$, average stellar age $\lt 1\, {\rm Myr}$ at z = 4. Finally, we are able to determine the minimal intrinsic flux required for HARMONI to detect Pop. III stars in a galaxy up to z = 10.

Original languageEnglish
Pages (from-to)5517-5537
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume501
Issue number4
DOIs
Publication statusPublished - 2021 Mar 1

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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