期刊
ASTROPHYSICAL JOURNAL
卷 784, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/784/1/58
关键词
galaxies: evolution; galaxies: formation; galaxies: high-redshift
资金
- ERC [227749]
- NASA through Hubble Fellowship [HST-HF-51334.01-A]
- STFC [ST/F001991/1, ST/J001511/1, ST/I000879/1] Funding Source: UKRI
Growing observational evidence indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z similar to 5-7 galaxies. This line emission makes z similar to 5-7 galaxies appear more massive, with lower specific star-formation rates (sSFRs). However, corrections for this line emission have been difficult to perform reliably because of huge uncertainties on the strength of such emission at z greater than or similar to 5.5. In this paper, we present the most direct observational evidence thus far for ubiquitous high-equivalent-width (EW) [O (III)]+ H beta line emission in Lyman-break galaxies at z similar to 7, and we present a strategy for an improved measurement of the sSFR at z similar to 7. We accomplish this through the selection of bright galaxies in the narrow redshift window z similar to 6.6-7.0 where the Spitzer/Infrared Array Camera (IRAC) 4.5 mu m flux provides a clean measurement of the stellar continuum light, in contrast with the 3.6 mu m flux, which is contaminated by the prominent [O III]+ H beta lines. To ensure a high signal-to-noise ratio for our IRAC flux measurements, we consider only the brightest (H-160 < 26 mag) magnified galaxies we have identified behind galaxy clusters. It is remarkable that the mean rest-frame optical color 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 require that the rest-frame EW of [O III]+ H beta is greater than 637 angstrom for the average source. The four bluest sources from our seven-source sample require an even more extreme EW of 1582 angstrom. We can also set a robust lower limit of greater than or similar to 4Gyr(-1) on the sSFR of our sample based on the mean spectral energy distribution.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据