%0 Generic %1 steidel2016reconciling %A Steidel, C. C. %A Strom, A. L. %A Pettini, M. %A Rudie, G. C. %A Reddy, N. A. %A Trainor, R. F. %D 2016 %K composite lbg lines metallicity nebular stellar %T Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies %U http://arxiv.org/abs/1605.07186 %X We present a combined analysis of rest-frame far-UV (1000-2000 A) and rest-frame optical (3600-7000 A) composite spectra formed from very deep observations of a sample of 30 star-forming galaxies with z=2.4+/-0.1, selected to be representative of the full KBSS-MOSFIRE spectroscopic survey. Since the same massive stars are responsible for the observed FUV continuum and the excitation of the observed nebular emission, a self-consistent stellar population synthesis model must simultaneously match the details of the far-UV stellar+nebular continuum and-- when inserted as the excitation source in photoionization models-- account for all observed nebular emission line ratios. We find that only models including massive star binaries, having low stellar metallicity (Z_*/Z_sun ~ 0.1) but relatively high ionized gas-phase oxygen abundances (Z_neb/Z_sun ~ 0.5), can successfully match all of the observational constraints. We argue that this apparent discrepancy is naturally explained by highly super-solar O/Fe 4-5 times (O/Fe)_sun, expected for gas whose enrichment is dominated by the products of core-collapse supernovae. Once the correct ionizing spectrum is identified, photoionization models reproduce all of the observed strong emission line ratios, the direct T_e measurement of O/H, and allow accurate measurement of the gas-phase abundance ratios of N/O and C/O -- both of which are significantly sub-solar but, as for O/Fe, are in remarkable agreement with abundance patterns observed in Galactic thick disk, bulge, and halo stars with similar O/H. High nebular excitation is the rule at high-z (and rare at low-z) because of systematically shorter enrichment timescales (<<1 Gyr): low Fe/O environments produce harder (and longer-lived) stellar EUV spectra at a given O/H, enhanced by dramatic effects on the evolution of massive star binaries.

@misc{steidel2016reconciling, abstract = {We present a combined analysis of rest-frame far-UV (1000-2000 A) and rest-frame optical (3600-7000 A) composite spectra formed from very deep observations of a sample of 30 star-forming galaxies with z=2.4+/-0.1, selected to be representative of the full KBSS-MOSFIRE spectroscopic survey. Since the same massive stars are responsible for the observed FUV continuum and the excitation of the observed nebular emission, a self-consistent stellar population synthesis model must simultaneously match the details of the far-UV stellar+nebular continuum and-- when inserted as the excitation source in photoionization models-- account for all observed nebular emission line ratios. We find that only models including massive star binaries, having low stellar metallicity (Z_*/Z_{sun} ~ 0.1) but relatively high ionized gas-phase oxygen abundances (Z_{neb}/Z_{sun} ~ 0.5), can successfully match all of the observational constraints. We argue that this apparent discrepancy is naturally explained by highly super-solar O/Fe [4-5 times (O/Fe)_{sun}], expected for gas whose enrichment is dominated by the products of core-collapse supernovae. Once the correct ionizing spectrum is identified, photoionization models reproduce all of the observed strong emission line ratios, the direct T_e measurement of O/H, and allow accurate measurement of the gas-phase abundance ratios of N/O and C/O -- both of which are significantly sub-solar but, as for O/Fe, are in remarkable agreement with abundance patterns observed in Galactic thick disk, bulge, and halo stars with similar O/H. High nebular excitation is the rule at high-z (and rare at low-z) because of systematically shorter enrichment timescales (<<1 Gyr): low Fe/O environments produce harder (and longer-lived) stellar EUV spectra at a given O/H, enhanced by dramatic effects on the evolution of massive star binaries.}, added-at = {2016-05-25T12:26:32.000+0200}, author = {Steidel, C. C. and Strom, A. L. and Pettini, M. and Rudie, G. C. and Reddy, N. A. and Trainor, R. F.}, biburl = {https://www.bibsonomy.org/bibtex/257154652cffe3d5ddf09cf9aa91359e7/miki}, description = {[1605.07186] Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies}, interhash = {b7b0a071c9ba8b18780c7293b4460c9b}, intrahash = {57154652cffe3d5ddf09cf9aa91359e7}, keywords = {composite lbg lines metallicity nebular stellar}, note = {cite arxiv:1605.07186Comment: 29 pages, 17 figures. Accepted for publication in the Astrophysical Journal}, timestamp = {2016-05-25T12:26:32.000+0200}, title = {Reconciling the Stellar and Nebular Spectra of High Redshift Galaxies}, url = {http://arxiv.org/abs/1605.07186}, year = 2016 }