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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Calibrating [O II] star formation rates at z > 1 from dual Hα-[O II] imaging from HiZELS
AU - Hayashi, Masao
AU - Sobral, David
AU - Best, Philip N.
AU - Smail, Ian
AU - Kodama, Tadayuki
PY - 2013/4/1
Y1 - 2013/4/1
N2 - We investigate the relationship between Hα and [O II](λ3727) emission in faint star-forming galaxies at z = 1.47 with dust uncorrected star formation rates (SFRs) down to 1.4M⊙ yr-1, using data in two narrow bands from wide-field camera/United Kingdom Infrared Telescope and Subaru prime focus camera/Subaru. A stacking analysis allows us to investigate Hα emission flux from bright [O II] emitters as well as faint ones for which Hα is not individually detected, and to compare them with a large sample of local galaxies. We find that there is a clear, positive correlation between the average Hα and [O II] luminosities for [O II] emitters at z = 1.47, with its slope being consistent with the local relation. [O II] emitters at z = 1.47 have lower mean observed ratios of Hα/[O II] suggesting a small but systematic offset (at 2.8σ significance) towards lower values of dust attenuation, AHα ~ 0.35, than local galaxies. This confirms that [O II] selection tends to pick up galaxies which are significantly less dusty on average than Hα-selected ones, with the difference being higher at z = 1.47 than at z = 0. The discrepancy of the observed line ratios between [O II] emitters at z=1.47 and the local galaxies may in part be due to the samples having different metallicities. However, we demonstrate that metallicity is unlikely to be the main cause. Therefore, it is important to take into account that the relations for the dust correction which are derived using Hα emitter samples, and frequently used in many studies of high-z galaxies, may overestimate the intrinsic SFRs of [O II]-selected galaxies, and that surveys of [OII] emission galaxies are likely to miss dusty populations.
AB - We investigate the relationship between Hα and [O II](λ3727) emission in faint star-forming galaxies at z = 1.47 with dust uncorrected star formation rates (SFRs) down to 1.4M⊙ yr-1, using data in two narrow bands from wide-field camera/United Kingdom Infrared Telescope and Subaru prime focus camera/Subaru. A stacking analysis allows us to investigate Hα emission flux from bright [O II] emitters as well as faint ones for which Hα is not individually detected, and to compare them with a large sample of local galaxies. We find that there is a clear, positive correlation between the average Hα and [O II] luminosities for [O II] emitters at z = 1.47, with its slope being consistent with the local relation. [O II] emitters at z = 1.47 have lower mean observed ratios of Hα/[O II] suggesting a small but systematic offset (at 2.8σ significance) towards lower values of dust attenuation, AHα ~ 0.35, than local galaxies. This confirms that [O II] selection tends to pick up galaxies which are significantly less dusty on average than Hα-selected ones, with the difference being higher at z = 1.47 than at z = 0. The discrepancy of the observed line ratios between [O II] emitters at z=1.47 and the local galaxies may in part be due to the samples having different metallicities. However, we demonstrate that metallicity is unlikely to be the main cause. Therefore, it is important to take into account that the relations for the dust correction which are derived using Hα emitter samples, and frequently used in many studies of high-z galaxies, may overestimate the intrinsic SFRs of [O II]-selected galaxies, and that surveys of [OII] emission galaxies are likely to miss dusty populations.
KW - Evolution
KW - Galaxies
KW - High-redshift
U2 - 10.1093/mnras/sts676
DO - 10.1093/mnras/sts676
M3 - Journal article
AN - SCOPUS:84876709300
VL - 430
SP - 1042
EP - 1050
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -