The MOSDEF Survey: Towards a Complete Census of the z ~ 2.3 Star-forming Galaxy Population

Jordan N. Runco, Alice E. Shapley, Ryan L. Sanders, Mariska Kriek, Naveen A. Reddy, Alison L. Coil, Bahram Mobasher, Brian Siana, Michael W. Topping, William R. Freeman, Irene Shivaei, Mojegan Azadi, Sedona H. Price, Gene C. K. Leung, Tara Fetherolf, Laura de Groot, Tom Zick, Francesca M. Fornasini, Guillermo Barro

Submitted on 29 June 2022


We analyze 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 (H_AB = 24.5). The subset of z ~ 2 MOSDEF galaxies with high signal-to-noise (S/N) emission-line detections analyzed in previous work represents a small minority (<10%) 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 colors; however, these offsets are minor considering the wide spread of the distributions. Using SED modeling, 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.


Comment: 18 pages, 10 figures, 3 tables

Subject: Astrophysics - Astrophysics of Galaxies