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ABSTRACT We analyse the completeness of the MOSDEF survey, in which z ∼ 2 galaxies were selected for rest-optical spectroscopy from well-studied HST extragalactic legacy fields down to a fixed rest-optical magnitude limit (HAB = 24.5). The subset of z ∼ 2 MOSDEF galaxies with high signal-to-noise (S/N) emission-line detections analysed in previous work represents a small minority (<10 per cent) of possible z ∼ 2 MOSDEF targets. It is therefore crucial to understand how representative this high S/N subsample is, while also more fully exploiting the MOSDEF spectroscopic sample. Using spectral-energy distribution (SED) models and rest-optical spectral stacking, we compare the MOSDEF z ∼ 2 high S/N subsample with the full MOSDEF sample of z ∼ 2 star-forming galaxies with redshifts, the latter representing an increase in sample size of more than a factor of three. We find that both samples have similar emission-line properties, in particular in terms of the magnitude of the offset from the local star-forming sequence on the [N ii] BPT diagram. There are small differences in median host galaxy properties, including the stellar mass (M*), star formation rate (SFR) and specific SFR (sSFR), and UVJ colours; however, these offsets are minor considering the wide spread of the distributions. Using SED modelling, we also demonstrate that the sample of z ∼ 2 star-forming galaxies observed by the MOSDEF survey is representative of the parent catalog of available such targets. We conclude that previous MOSDEF results on the evolution of star-forming galaxy emission-line properties were unbiased relative to the parent z ∼ 2 galaxy population.
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Reconciling the results of the z ∼ 2 MOSDEF and KBSS-MOSFIRE Surveys
ABSTRACT The combination of the MOSDEF and KBSS-MOSFIRE surveys represents the largest joint investment of Keck/MOSFIRE time to date, with ∼3000 galaxies at 1.4 ≲ z ≲ 3.8, roughly half of which are at z ∼ 2. MOSDEF is photometric- and spectroscopic-redshift selected with a rest-optical magnitude limit, while KBSS-MOSFIRE is primarily selected based on rest-UV colours and a rest-UV magnitude limit. Analysing both surveys in a uniform manner with consistent spectral-energy-distribution (SED) models, we find that the MOSDEF z ∼ 2 targeted sample has higher median M* and redder rest U−V colour than the KBSS-MOSFIRE z ∼ 2 targeted sample, and smaller median SED-based SFR and sSFR (SFR(SED) and sSFR(SED)). Specifically, MOSDEF targeted a larger population of red galaxies with U−V and V−J ≥1.25, while KBSS-MOSFIRE contains more young galaxies with intense star formation. Despite these differences in the z ∼ 2 targeted samples, the subsets of the surveys with multiple emission lines detected and analysed in previous work are much more similar. All median host-galaxy properties with the exception of stellar population age – i.e. M*, SFR(SED), sSFR(SED), AV, and UVJ colours – agree within the uncertainties. Additionally, when uniform emission-line fitting and stellar Balmer absorption correction techniques are applied, there is no significant offset between both samples in the [O iii]λ5008/H β versus [N ii]λ6585/H α diagnostic diagram, in contrast to previously reported discrepancies. We can now combine the MOSDEF and KBSS-MOSFIRE surveys to form the largest z ∼ 2 sample with moderate-resolution rest-optical spectra and construct the fundamental scaling relations of star-forming galaxies during this important epoch.
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- PAR ID:
- 10367460
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 513
- Issue:
- 3
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- p. 3871-3892
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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