%0 Generic %1 Kriek2011 %A Kriek, Mariska %A van Dokkum, Pieter G. %A Whitaker, Katherine E. %A Labbe, Ivo %A Franx, Marijn %A Brammer, Gabriel B. %D 2011 %K galaxy high-z sfr spectra %T Halpha and 4000 Angstrom Break Measurements for ~3500 K-selected Galaxies at 0.5<z<2.0 %U http://arxiv.org/abs/1103.0279 %X We use the high-quality photometry of the NEWFIRM medium-band survey (NMBS) in the COSMOS field to study correlations between Halpha emission, the 4000 Angstrom break, and the specific star formation rate (SSFR) of ~3500 K-selected galaxies at 0.5<z<2.0. Based on the full SED shape, we identify analogous galaxies and construct a sample of 32 different SED types. For each type we make a composite SED by de-redshifting and scaling the observed photometry. The composite SEDs are of spectroscopic quality. We measure the equivalent width (EW) of Halpha, the strength of the 4000 Angstrom break (Dn(4000)), and derive the best-fit SSFR. All these properties are strongly correlated: galaxies with shallow breaks have high Halpha EWs and are best fit by stellar population models with high SSFR, while galaxies with low SSFRs and strong 4000 Angstrom breaks have low Halpha EWs. There is also a correlation with morphology: with increasing Dn(4000), galaxies appear to change from irregular and clumpy, to fairly regular disks, to regular early-type systems at the highest Dn(4000). Strikingly, the most dusty galaxies are typically edge-on disks. The relation between the Halpha EW and Dn(4000) is similar to the low-redshift relation, with a slight offset to higher Halpha EWs at fixed Dn(4000). A comparison of the observed relation to stellar population synthesis models suggests that the suppression of star formation in galaxies is not abrupt, but a gradual process. Altogether, the NMBS opens up efficient studies of Halpha and other spectroscopic features for large samples of distant galaxies, which would otherwise require extensive near-infrared spectroscopic campaigns.

@misc{Kriek2011, abstract = { We use the high-quality photometry of the NEWFIRM medium-band survey (NMBS) in the COSMOS field to study correlations between Halpha emission, the 4000 Angstrom break, and the specific star formation rate (SSFR) of ~3500 K-selected galaxies at 0.5&lt;z&lt;2.0. Based on the full SED shape, we identify analogous galaxies and construct a sample of 32 different SED types. For each type we make a composite SED by de-redshifting and scaling the observed photometry. The composite SEDs are of spectroscopic quality. We measure the equivalent width (EW) of Halpha, the strength of the 4000 Angstrom break (Dn(4000)), and derive the best-fit SSFR. All these properties are strongly correlated: galaxies with shallow breaks have high Halpha EWs and are best fit by stellar population models with high SSFR, while galaxies with low SSFRs and strong 4000 Angstrom breaks have low Halpha EWs. There is also a correlation with morphology: with increasing Dn(4000), galaxies appear to change from irregular and clumpy, to fairly regular disks, to regular early-type systems at the highest Dn(4000). Strikingly, the most dusty galaxies are typically edge-on disks. The relation between the Halpha EW and Dn(4000) is similar to the low-redshift relation, with a slight offset to higher Halpha EWs at fixed Dn(4000). A comparison of the observed relation to stellar population synthesis models suggests that the suppression of star formation in galaxies is not abrupt, but a gradual process. Altogether, the NMBS opens up efficient studies of Halpha and other spectroscopic features for large samples of distant galaxies, which would otherwise require extensive near-infrared spectroscopic campaigns. }, added-at = {2011-03-03T18:35:37.000+0100}, author = {Kriek, Mariska and van Dokkum, Pieter G. and Whitaker, Katherine E. and Labbe, Ivo and Franx, Marijn and Brammer, Gabriel B.}, biburl = {https://www.bibsonomy.org/bibtex/25fd54069cba4e72955ee210784da2311/miki}, description = {[1103.0279] Halpha and 4000 Angstrom Break Measurements for ~3500 K-selected Galaxies at 0.5<z<2.0}, interhash = {c8e4331566db77c7c1621c209523e2bf}, intrahash = {5fd54069cba4e72955ee210784da2311}, keywords = {galaxy high-z sfr spectra}, note = {cite arxiv:1103.0279 Comment: Submitted to ApJ, high-resolution version can be downloaded at https://www.cfa.harvard.edu/~mkriek/papers/}, timestamp = {2011-03-03T18:35:37.000+0100}, title = {Halpha and 4000 Angstrom Break Measurements for ~3500 K-selected Galaxies at 0.5&lt;z&lt;2.0}, url = {http://arxiv.org/abs/1103.0279}, year = 2011 }