English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

By combining optical and near-IR observations from the Hubble Space Telescopewith NIR photometry from the Spitzer Space Telescope it is possible to measurethe rest-frame UV-optical colours of galaxies at z=4-8. The UV-optical spectralenergy distribution of star formation dominated galaxies is the result ofseveral different factors. These include the joint distribution of stellarmasses, ages, and metallicities, and the subsequent reprocessing by dust andgas in the ISM. Using a large cosmological hydrodynamical simulation weinvestigate the predicted spectral energy distributions of galaxies athigh-redshift with a particular emphasis on assessing the potentialcontribution of nebular emission. We find that the average pure stellarUV-optical colour correlates with both luminosity and redshift such thatgalaxies at lower-redshift and higher-luminosity are typically redder. Assumingthe escape fraction of ionising photons is close to zero, the effect of nebularemission is to redden the UV-optical 1500-V_w colour by, on average, 0.4 mag atz=8 declining to 0.25 mag at z=4. Young and low-metallicity stellarpopulations, which typically have bluer pure stellar UV-optical colours,produce larger ionising luminosities and are thus more strongly affected by thereddening effects of nebular emission. This causes the distribution of 1500-V_wcolours to narrow and the trends with luminosity and redshift to weaken. Thestrong effect of nebular emission leaves observed-frame colours criticallysensitive to the source redshift. For example, increasing the redshift by 0.1can result in observed frame colours changing by up to ~0.6. These predictionsreinforce the need to include nebular emission when modelling the spectralenergy distributions of galaxies at high-redshift and also highlight thedifficultly in interpreting the observed colours of individual galaxies withoutprecise redshifts.

Theoretical predictions for the effect of nebular emission on the broad band photometry of high-redshift galaxies