Nebular emission line ratios in z~2-3 star-forming galaxies: exploring the impact of ionization, excitation, and abundance patterns

Add to your list(s) Download to your calendar using vCal

• Allison Strom (Caltech)
• Friday 17 June 2016, 11:30-12:30
• Kavli LMR, IoA.

If you have a question about this talk, please contact Martin Haehnelt.

I will present new results from the MOSFIRE component of the Keck Baryonic Structure Survey (KBSS-MOSFIRE), focusing on the rest-optical spectra of around 350 star-forming galaxies at z=2-3, for which we have robust measurements of many of the strong diagnostic emission lines (including H-alpha, H-beta, [OIII], [OII], [NII], [SII], and [NeIII]). The observations strongly suggest that the primary difference between HII regions in z=2 galaxies and those in local galaxies is a strong enhancement in the degree of excitation, driven by the hard ionizing radiation from populations of metal-poor stars. At the same time, z=2 KBSS -MOSFIRE galaxies have significantly higher gas-phase oxygen abundances than local star-forming galaxies with similar ionization and excitation properties, along with values of N/O at fixed O/H that are consistent with galaxies in the local Universe. I will show that the combination of these two effects naturally explains the combined nebular properties of high-z galaxies—-including the controversial ‘BPT offset’—-and highlights a population of young, massive galaxies at high-redshift that must have accumulated their stellar mass significantly more rapidly than the majority of galaxies today.

This talk is part of the Galaxies Discussion Group series.

This talk is included in these lists:

• Combined External Astrophysics Talks DAMTP
• Cosmology, Astrophysics and General Relativity
• Galaxies Discussion Group
• Institute of Astronomy Talk Lists
• Kavli Institute for Cosmology Talk Lists
• Kavli LMR, IoA

Note that ex-directory lists are not shown.