The Stellar Population Completeness of Narrow-band Emission-line Surveys
Abstract
Narrow-band surveys have been conducted to identify high redshift star-forming galaxies by detecting their nebular emission lines when redshifted into narrow bandpasses. Such surveys have yielded large samples from low redshifts (z<0.4) to as high as z=7. These surveys have the ability to (1) measure redshifts to 1 percent accuracy, (2) derive robust emission line fluxes, which can be used to determine star-formation rates (SFRs) and trace the cosmic SFR density, and (3) is roughly ten times more efficient than spectroscopic surveys in terms of (1) and (2).
In this poster, we illustrate a unique advantage of these narrow-band surveys in identifying star-forming galaxies that span a wide range of physical properties. This survey is the first to study the stellar population completeness of emission-line surveys. It utilizes two samples of [O II] emitters at z=1.47 and z=1.61 in the Subaru Deep Field. The survey consists of 1,200 emission-line galaxies with accurate photometric redshifts, and photometric coverage over 22 wave-bands (1500 Angstroms to 4.5 µm). We find that these [O II] samples simultaneously probed the two extremes (from the bluest to the reddest) of galaxy populations. That is, the [O II] emitters are also selected as BX/BM (UV) galaxies and/or the star-forming BzK (NIR) galaxies. We attribute this success to the adopted low minimum observed equivalent width (EW) of 10 Angstroms. In addition, we find that roughly 10% of the z=1.47 [O II] emitters are not selected by either the UV or NIR techniques. These galaxies have the reddest rest-frame optical colors and very low [O II] EWs. We argue that ultra-deep narrow-band surveys are able to catch the most reddenned galaxies by detecting their weak, dust-obscured emission lines, which standard color selections, including NIR techniques, miss.- Publication:
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American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21733513L