The MOSDEF Survey: Outflows from Broadened Emission Lines at z=[1.3 - 3.8]
Abstract
We present results from the MOSFIRE Deep Evolution Field (MOSDEF) survey on broad emission from the nebular emission lines H-alpha, [NII], [OIII], H-beta, and [SII]. After removing known AGN, the sample consists of 171 galaxies with 1.37 < z < 2.61 and 84 galaxies with 2.95 < z < 3.80. We study broad flux by decomposing the emission lines using narrow and broad components for individual galaxies and stacks. For the z~2 sample, the broad flux accounts for 20-50% of the flux in nebular emission lines and in the z~3.3 sample the broad component comprises 30-60% of the flux. We estimate the mass loading factor (mass outflow rate/SFR), assuming the outflow is photoionized, as a function of SFR, mass, sSFR, and star formation surface density and compare to recent simulations. We find our galaxies are compatible with simulations only if a large fraction of the outflowing material is <300 km/s for galaxies below 10^10 stellar mass. We calculate [SII]/H-alpha, [NII]/H-alpha, and [OIII]/H-beta line ratios for the narrow components and broad components. When placed on the BPT diagram ([OIII]/H-beta vs. [NII]/H-alpha) the broad components are shifted towards the higher [OIII]/H-beta and [NII]/H-alpha ratios. This is likely the results of shocks or low luminosity AGN. The narrow component line ratios are closer to local measurements than other studies at z~2 but are still slightly offset. Outflows and shocks may significantly alter measurements made from emission lines and line ratios.
- Publication:
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American Astronomical Society Meeting Abstracts #229
- Pub Date:
- January 2017
- Bibcode:
- 2017AAS...22922904F