%0 Generic %1 chevallard2017ionization %A Chevallard, Jacopo %A Charlot, Stéphane %A Senchyna, Peter %A Stark, Daniel P. %A Vidal-García, Alba %A Feltre, Anna %A Gutkin, Julia %A Jones, Tucker %A Mainali, Ramesh %A Wofford, Aida %D 2017 %K [OIII] formation ionisation lines region star %T The ionization properties of extreme nearby star-forming regions %U http://arxiv.org/abs/1709.03503 %X The bulk of hydrogen-ionizing photons necessary to reionize the intergalactic medium (IGM) by redshift z~6 is likely to have arisen from stars in low-mass galaxies. Whether these galaxies were numerous enough at z>6 to reionize the IGM entirely depends on their production rate of H-ionizing photons, xi_ion, and the fraction of these escaping into the IGM. We derive a novel diagnostic of xi_ion based on the equivalent width of the bright OIII4959,5007 line doublet, which does not require measurements of H-recombination lines. We calibrate this diagnostic through the analysis of the luminosities of 15 nebular emission lines in high-quality optical spectra of 10 low-redshift analogs of primeval galaxies, using the new-generation spectral analysis tool Beagle. The success of this analysis confirms the ability of the models to constrain the ionized-gas properties of extreme star-forming regions, paving the way to similar analyses at high redshift. The new xi_ion diagnostic can be used to derive more accurate estimates of this parameter than currently possible from the contamination by Hbeta+OIII4959,5007 of broad-band photometry in distant galaxies, and, in the future, from direct observations of OIII4959,5007 out to z~9.5 using JWST/NIRSpec.

@misc{chevallard2017ionization, abstract = {The bulk of hydrogen-ionizing photons necessary to reionize the intergalactic medium (IGM) by redshift z~6 is likely to have arisen from stars in low-mass galaxies. Whether these galaxies were numerous enough at z>6 to reionize the IGM entirely depends on their production rate of H-ionizing photons, xi_ion, and the fraction of these escaping into the IGM. We derive a novel diagnostic of xi_ion based on the equivalent width of the bright [OIII]4959,5007 line doublet, which does not require measurements of H-recombination lines. We calibrate this diagnostic through the analysis of the luminosities of 15 nebular emission lines in high-quality optical spectra of 10 low-redshift analogs of primeval galaxies, using the new-generation spectral analysis tool Beagle. The success of this analysis confirms the ability of the models to constrain the ionized-gas properties of extreme star-forming regions, paving the way to similar analyses at high redshift. The new xi_ion diagnostic can be used to derive more accurate estimates of this parameter than currently possible from the contamination by Hbeta+[OIII]4959,5007 of broad-band photometry in distant galaxies, and, in the future, from direct observations of [OIII]4959,5007 out to z~9.5 using JWST/NIRSpec.}, added-at = {2017-09-13T11:52:49.000+0200}, author = {Chevallard, Jacopo and Charlot, Stéphane and Senchyna, Peter and Stark, Daniel P. and Vidal-García, Alba and Feltre, Anna and Gutkin, Julia and Jones, Tucker and Mainali, Ramesh and Wofford, Aida}, biburl = {https://www.bibsonomy.org/bibtex/232e8666a61f999f77abd6ef3fa131ba3/miki}, description = {[1709.03503] The ionization properties of extreme nearby star-forming regions}, interhash = {ba9138b51bdde8437aed2ccf1e0b3459}, intrahash = {32e8666a61f999f77abd6ef3fa131ba3}, keywords = {[OIII] formation ionisation lines region star}, note = {cite arxiv:1709.03503Comment: 6 pages, 5 figures, submitted to MNRAS Letters, comments welcome}, timestamp = {2017-09-13T11:52:49.000+0200}, title = {The ionization properties of extreme nearby star-forming regions}, url = {http://arxiv.org/abs/1709.03503}, year = 2017 }