EMU/GAMA: Refining dust extinction corrections for Hα luminosity functions using radio-based calibration

Publications of the Astronomical Society of Australia, vol. 43

Abstract

Abstract We present a novel approach to correcting H ${\unicode{x03B1}}$ luminosity functions for dust extinction by calibrating against radio-based star formation rates (SFRs), using data from the Evolutionary Map of the Universe (EMU) and Galaxy and Mass Assembly (GAMA) surveys. Accurate dust correction is essential for deriving SFRs from rest-frame UV-optical emission lines, particularly as the James Webb Space Telescope extends such measurements to galaxies at $z\gt5$ . While a luminosity dependence of dust obscuration has long been recognised, our method exploits the empirical relationship between obscured (H ${\unicode{x03B1}}$ ) and unobscured (radio) SFRs to provide a dust correction that can be applied where traditional spectroscopic techniques, for example, Balmer line based approaches, are unavailable. We apply the SFR based dust correction to 25 published H ${\unicode{x03B1}}$ luminosity functions spanning $0\lt z\lt 8$ and derive corresponding star formation rate densities (SFRDs). Adopting the locally calibrated H ${\unicode{x03B1}}$ –radio relation ends up with an overestimate of the cosmic SFRD by more than two orders of magnitude at $z\gtrsim1$ . Motivated by the luminosity dependent relation in the local Universe, we introduce a new model where the luminosity dependence of the dust obscuration decreases with increasing redshift. This approach can reproduce observed SFRDs across cosmic time. These results highlight the potential of a radio-based calibration for dust correction, where a luminosity dependent correction would need to decline in strength with increasing redshift. This implies that the dust content or distribution in galaxies at early epochs differs substantially from that in the local Universe.

Authors 20

1. Jayde Willingham corresponding

   Macquarie University

   Affiliation as printed

   Macquarie University

2. Andrew Hopkins

   Macquarie University

   Affiliation as printed

   Macquarie University

3. Tayyaba Zafar

   Macquarie University

   Affiliation as printed

   Macquarie University

4. J. Afonso

   University of Lisbon

   Affiliation as printed

   Universidade de Lisboa

5. UT Ahmed

   University of Southern Queensland · Macquarie University

   Affiliation as printed

   Macquarie University

   University of Southern Queensland

6. A. Ahmad

   Western Sydney University

   Affiliation as printed

   Western Sydney University

7. Andrew J Battisti

   Australian National University · The University of Western Australia

   Affiliation as printed

   Australian National University

   The University of Western Australia

8. D. J. Bomans

   Ruhr University Bochum

   Affiliation as printed

   Astronomisches Institut (AIRUB), Ruhr-Universität

9. M. J. I. Brown

   Monash University

   Affiliation as printed

   Monash University

10. Michael J. Cowley

    Queensland University of Technology · University of Southern Queensland

    Affiliation as printed

    Queensland University of Technology

    University of Southern Queensland

11. D. Farrah

    University of Hawaiʻi at Mānoa

    Affiliation as printed

    University of Hawai’i at Manoa

    University of Hawai’i at Māanoa

12. T.J. Galvin

    Commonwealth Scientific and Industrial Research Organisation · Curtin University

    Affiliation as printed

    CSIRO Space and Astronomy

    Curtin University

13. Benne Willem Holwerda Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University

14. Denis Alan Leahy

    University of Calgary

    Affiliation as printed

    University of Calgary

15. Umberto Maio

    Institute for Fundamental Physics of the Universe

    Affiliation as printed

    IFPU – Institute for Fundamental Physics of the Universe

16. Tamal Mukherjee

    Macquarie University

    Affiliation as printed

    Macquarie University

17. Jahang Prathap

    Macquarie University

    Affiliation as printed

    Macquarie University

18. Nicholas Seymour

    Curtin University

    Affiliation as printed

    Curtin University

19. Jacco Th. van Loon

    Keele University

    Affiliation as printed

    Keele University

20. E. Ward

    Macquarie University

    Affiliation as printed

    Macquarie University