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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Growing observational evidence now indicates that nebular line emission has asignificant impact on the rest-frame optical fluxes of z~5-7 galaxies observedwith Spitzer. This line emission makes z~5-7 galaxies appear more massive, withlower specific star formation rates. However, corrections for this lineemission have been very difficult to perform reliably due to huge uncertaintieson the overall strength of such emission at z>~5.5. Here, we present the mostdirect observational evidence yet for ubiquitous high-EW [OIII]+Hbeta lineemission in Lyman-break galaxies at z~7, while also presenting a strategy foran improved measurement of the sSFR at z~7. We accomplish this through theselection of bright galaxies in the narrow redshift window z~6.6-7.0 where theIRAC 4.5 micron flux provides a clean measurement of the stellar continuumlight. Observed 4.5 micron fluxes in this window contrast with the 3.6 micronfluxes which are contaminated by the prominent [OIII]+Hbeta lines. To ensure ahigh S/N for our IRAC flux measurements, we consider only the brightest(H_{160}<26 mag) magnified galaxies we have identified in CLASH and otherprograms targeting galaxy clusters. Remarkably, the mean rest-frame opticalcolor for our bright seven-source sample is very blue, [3.6]-[4.5]=-0.9+/-0.3.Such blue colors cannot be explained by the stellar continuum light and requirethat the rest-frame EW of [OIII]+Hbeta be greater than 637 Angstroms for theaverage source. The bluest four sources from our seven-source sample require aneven more extreme EW of 1582 Angstroms. Our derived lower limit for the mean[OIII]+Hbeta EW could underestimate the true EW by ~2x based on a simplemodeling of the redshift distribution of our sources. We can also set a robustlower limit of >~4 Gyr^-1 on the specific star formation rates based on themean SED for our seven-source sample. (abridged)

astrophysical journal/the astrophysical journal

Evidence for Ubiquitous, High-EW Nebular Emission in z~7 Galaxies:  Towards a Clean Measurement of the Specific Star Formation Rate using a  Sample of Bright, Magnified Galaxies