The impact of nebular emission on the ages of z~6 galaxies

By Daniel Schaerer, S. de Barros. 2009

233 citations recorded by the source corpus.

We examine the influence of nebular continuous and line emission in high redshift star forming galaxies on determinations of their age, formation redshift and other properties from SED fits. We include nebular emission consistently with the stellar emission in our SED fitting tool and analyse differentially a sample of 10 z~6 galaxies in the GOODS-S field studied earlier by Eyles et al. (2007). We find that the apparent Balmer/4000 Ang breaks observed in a number of z~6 galaxies detected at >~3.6 micron with IRAC/Spitzer can be mimicked by the presence of strong restframe optical emission lines, implying in particular younger ages than previously thought. Applying these models to the small sample of z~6 galaxies, we find that this effect may lead to a typical downward revision of their stellar ages by a factor ~3. In consequence their average formation redshift may drastically be reduced, and these objects may not have contributed to cosmic reionisation at z>6. Extinction and stellar mass estimates may also be somewhat modified, but to a lesser extent. Careful SED fits including nebular emission and treating properly uncertainties and degeneracies are necessary for more accurate determinations of the physical parameters of high-z galaxies.

View Paper: https://www.semanticscholar.org/paper/f9f4fd4e473f2c91e60f40c84a9ae74bf0cfe704

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

1. T. Treu
2. M. Oguri
3. Y. Harikane
4. C. Mason
5. Y. Isobe
6. Yechi Zhang
7. Hiroya Umeda
8. M. Bradač

Citations in the corpus

• Early Results from GLASS-JWST. III. Galaxy Candidates at z ∼9–15 (2022, methodology): “As described by Merlin et al. (2021), the BC03 library includes templates with both declining and delayed starformation histories and models the contribution from nebular continuum and line emission following Schaerer & de Barros (2009) and Castellano et al. (2014).”
• A Comprehensive Study of Galaxies at z ∼ 9–16 Found in the Early JWST Data: Ultraviolet Luminosity Functions and Cosmic Star Formation History at the Pre-reionization Epoch (2022, background): “…with top-heavy IMFs (PopIII.1 and PopIII.2 in YGGDRASIL) produce ∼3–4 times more UV photons than the canonical assumption given the SFR, because nebular continuum emission boosts the UV luminosity as discussed in previous studies (e.g., Zackrisson et al. 2008; Schaerer & de Barros 2009, 2010).”