English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We analyze the rest-optical emission-line spectra of $z\sim2.3$ star-forminggalaxies in the complete MOSFIRE Deep Evolution Field (MOSDEF) survey. Ininvestigating the origin of the well-known offset between the sequences ofhigh-redshift and local galaxies in the [O III]5008/H$\beta$ vs. [NII]6585/H$\alpha$ ("[N II] BPT") diagram, we define two populations of$z\sim2.3$ MOSDEF galaxies. These include the "high" population that is offsettowards higher [O III]5008/H$\beta$ and/or [N II]6585/H$\alpha$ with respect tothe local SDSS sequence and the "low" population that overlaps the SDSSsequence. These two groups are also segregated within the [O III]5008/H$\beta$vs. [S II]6718,6733/H$\alpha$ and the [O III]4960,5008/[O II]3727,3730(O$_{32}$) vs. ([O III]4960,5008+[O II]3727,3730)/H$\beta$ (R$_{23}$) diagram,which suggests qualitatively that star-forming regions in the more offsetgalaxies are characterized by harder ionizing spectra at fixed nebular oxygenabundance. We also investigate many galaxy properties of the split sample andfind that the "high" sample is on average smaller in size and less massive, buthas higher specific star-formation rate and star-formation-rate surface densityvalues and is slightly younger compared to the "low" population. FromCloudy+BPASS photoionization models, we estimate that the "high" population hasa lower stellar metallicity (i.e., harder ionizing spectrum) but slightlyhigher nebular metallicity and higher ionization parameter compared to the"low" population. While the "high" population is more $\alpha$-enhanced (i.e.,higher $\alpha$/Fe) than the "low" population, both samples are significantlymore $\alpha$-enhanced compared to local star-forming galaxies with similarrest-optical line ratios. These differences must be accounted for in allhigh-redshift star-forming galaxies -- not only those "offset" from localexcitation sequences.

The MOSDEF Survey: A Comprehensive Analysis of the Rest-optical Emission-line Properties of $z\sim 2.3$ Star-forming Galaxies