Dust masses of z > 5 galaxies from SED fitting and ALMA upper limits
Abstract
We aim at constraining the dust mass in high-z (z ≳ 5) galaxies using the upper limits obtained by Atacama Large Millimetre/submillimetre Array (ALMA) in combination with the rest-frame UV-optical spectral energy distributions (SEDs). For SED fitting, because of degeneracy between dust extinction and stellar age, we focus on two extremes: continuous star formation (Model A) and instantaneous star formation (Model B). We apply these models to Himiko (as a representative UV-bright object) and a composite SED of z > 5 Lyman break galaxies (LBGs). For Himiko, Model A requires a significant dust extinction, which leads to a high dust temperature >70 K for consistency with the ALMA upper limit. This high dust temperature puts a strong upper limit on the total dust mass Md ≲ 2 × 106 M⊙, and the dust mass produced per supernova (SN) md,SN ≲ 0.1 M⊙. Such a low md, SN suggests significant loss of dust by reverse shock destruction or outflow, and implies that SNe are not the dominant source of dust at high z. Model B allows Md ∼ 2 × 107 M⊙ and md,SN ∼ 0.3 M⊙. We could distinguish between Models A and B if we observe Himiko at wavelength < 1.2 mm by ALMA. For the LBG sample, we obtain Md ≲ 2 × 106 M⊙ for a typical LBG at z > 5, but this only puts an upper limit for md,SN as ∼2 M⊙. This clarifies the importance of observing UV-bright objects (like Himiko) to constrain the dust production by SNe.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2017
- DOI:
- 10.1093/mnras/stx2349
- arXiv:
- arXiv:1709.02526
- Bibcode:
- 2017MNRAS.472.4587H
- Keywords:
-
- dust;
- extinction;
- galaxies: evolution;
- galaxies: high-redshift;
- galaxies: ISM;
- galaxies: star formation;
- submillimetre: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 12 pages, 6 figures, accepted for publication in MNRAS