%0 Generic %1 kashino2016fmoscosmos %A Kashino, D. %A Silverman, J. D. %A Sanders, D. %A Kartaltepe, J. S. %A Daddi, E. %A Renzini, A. %A Valentino, F. %A Rodighiero, G. %A Juneau, S. %A Kewley, L. J. %A Zahid, H. J. %A Arimoto, N. %A Nagao, T. %A Chu, J. %A Sugiyama, N. %A Civano, F. %A Ilbert, O. %A Kajisawa, M. %A Fevre, O. Le %A Maier, C. %A Onodera, M. %A Puglisi, A. %A Taniguchi, Y. %A COSMOS, %D 2016 %K emission forming galaxies high-z lines star %T The FMOS-COSMOS survey of star-forming galaxies at z~1.6. IV: Excitation state and chemical enrichment of HII regions %U http://arxiv.org/abs/1604.06802 %X We present results on the physical conditions of the interstellar medium of star-forming galaxies at 1.4<~z<~1.7 from the FMOS-COSMOS survey. We use a sample of 701 galaxies, for which the H$\alpha$ emission line is detected, that represents the star-forming population over the stellar mass range 10^9.6<~M*/Msun<~10^11.6 with those at M*>10^11Msun being well sampled. The excitation state and chemical enrichment of the ionized gas are investigated using diagnostic diagrams based on the ratios of emission line strengths, including Alpha, NII6584, SII6717,6731, Hbeta, and OIII5007. Our data confirm an offset of the star-forming sequence on the BPT diagram (OIII/Hbeta vs. NII/Halpha), primarily towards higher OIII/Hbeta, compared with local star-forming galaxies. Based on the SII ratio, we measure an electron density (n_e=222^+172_-128 cm^-3), higher than that of local galaxies. Overall, these changes in emission-line properties are due to a higher ionization parameter in high redshift galaxies as demonstrated by a lower than expected SII/Halpha ratio and a comparison to theoretical models. These results likely rule out an offset in the BPT diagram caused by a harder radiation field or AGN as assessed with Chandra. Finally, we revisit the mass-metallicity relation by using a conventional NII/Halpha-based indicator and a new calibration based on the NII/SII ratio introduced by Dopita et al. Consistent with our previous results, the most massive galaxies (M*>~10^11Msun) are fully enriched, while lower mass galaxies have metallicities considerably lower than local galaxies, in agreement with many studies. In addition, we show that the FMOS sample is inconsistent with a "fundamental metallicity relation", though well-fit with a physically-motivated model of galaxy evolution with gas regulation.

@misc{kashino2016fmoscosmos, abstract = {We present results on the physical conditions of the interstellar medium of star-forming galaxies at 1.4<~z<~1.7 from the FMOS-COSMOS survey. We use a sample of 701 galaxies, for which the H$\alpha$ emission line is detected, that represents the star-forming population over the stellar mass range 10^9.6<~M*/Msun<~10^11.6 with those at M*>10^11Msun being well sampled. The excitation state and chemical enrichment of the ionized gas are investigated using diagnostic diagrams based on the ratios of emission line strengths, including Alpha, [NII]6584, [SII]6717,6731, Hbeta, and [OIII]5007. Our data confirm an offset of the star-forming sequence on the BPT diagram ([OIII]/Hbeta vs. [NII]/Halpha), primarily towards higher [OIII]/Hbeta, compared with local star-forming galaxies. Based on the [SII] ratio, we measure an electron density (n_e=222^{+172}_{-128} cm^-3), higher than that of local galaxies. Overall, these changes in emission-line properties are due to a higher ionization parameter in high redshift galaxies as demonstrated by a lower than expected [SII]/Halpha ratio and a comparison to theoretical models. These results likely rule out an offset in the BPT diagram caused by a harder radiation field or AGN as assessed with Chandra. Finally, we revisit the mass-metallicity relation by using a conventional [NII]/Halpha-based indicator and a new calibration based on the [NII]/[SII] ratio introduced by Dopita et al. Consistent with our previous results, the most massive galaxies (M*>~10^11Msun) are fully enriched, while lower mass galaxies have metallicities considerably lower than local galaxies, in agreement with many studies. In addition, we show that the FMOS sample is inconsistent with a "fundamental metallicity relation", though well-fit with a physically-motivated model of galaxy evolution with gas regulation.}, added-at = {2016-04-26T10:56:04.000+0200}, author = {Kashino, D. and Silverman, J. D. and Sanders, D. and Kartaltepe, J. S. and Daddi, E. and Renzini, A. and Valentino, F. and Rodighiero, G. and Juneau, S. and Kewley, L. J. and Zahid, H. J. and Arimoto, N. and Nagao, T. and Chu, J. and Sugiyama, N. and Civano, F. and Ilbert, O. and Kajisawa, M. and Fevre, O. Le and Maier, C. and Onodera, M. and Puglisi, A. and Taniguchi, Y. and COSMOS}, biburl = {https://www.bibsonomy.org/bibtex/23bf0a618c04283f5a8491b5ebcc290b4/miki}, description = {[1604.06802] The FMOS-COSMOS survey of star-forming galaxies at z~1.6. IV: Excitation state and chemical enrichment of HII regions}, interhash = {e3b94303090ec887b1ba946ca866a598}, intrahash = {3bf0a618c04283f5a8491b5ebcc290b4}, keywords = {emission forming galaxies high-z lines star}, note = {cite arxiv:1604.06802Comment: 22 pages, 17 Figures, submitted to ApJ}, timestamp = {2016-04-26T10:56:04.000+0200}, title = {The FMOS-COSMOS survey of star-forming galaxies at z~1.6. IV: Excitation state and chemical enrichment of HII regions}, url = {http://arxiv.org/abs/1604.06802}, year = 2016 }