The MOSDEF survey: Dissecting the star formation rate versus stellar mass relation using Hα and Hβ emission lines at z ∼ 2

Irene Shivaei, Naveen A. Reddy, Alice E. Shapley, Mariska Kriek, Brian Siana, Bahram Mobasher, Alison L. Coil, William R. Freeman, Ryan Sanders, Sedona H. Price, Laura De Groot, Mojegan Azadi

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

We present results on the star formation rate (SFR) versus stellar mass (M) relation (i.e., the "main sequence") among star-forming galaxies at 1.37 ≤ z ≤ 2.61 using the MOSFIRE Deep Evolution Field (MOSDEF) survey. Based on a sample of 261 galaxies with Hα and Hβ spectroscopy, we have estimated robust dust-corrected instantaneous SFRs over a large range in M (∼109.5-1011.5 Mo). We find a correlation between log(SFR(Hα)) and log(M) with a slope of 0.65 ± 0.08 (0.58 ± 0.10) at 1.4 < z < 2.6 (2.1 < z < 2.6). We find that different assumptions for the dust correction, such as using the color excess of the stellar continuum to correct the nebular lines, sample selection biases against red star-forming galaxies, and not accounting for Balmer absorption, can yield steeper slopes of the log(SFR)-log(M) relation. Our sample is immune from these biases as it is rest-frame optically selected, Hα and Hβ are corrected for Balmer absorption, and the Hα luminosity is dust corrected using the nebular color excess computed from the Balmer decrement. The scatter of the log(SFR(Hα))-log(M) relation, after accounting for the measurement uncertainties, is 0.31 dex at 2.1 < z < 2.6, which is 0.05 dex larger than the scatter in log(SFR(UV))-log(M). Based on comparisons to a simulated SFR-M relation with some intrinsic scatter, we argue that in the absence of direct measurements of galaxy-to-galaxy variations in the attenuation/extinction curves and the initial mass function, one cannot use the difference in the scatter of the SFR(Hα)- and SFR(UV)-M relations to constrain the stochasticity of star formation in high-redshift galaxies.

Original languageEnglish
Article number98
JournalAstrophysical Journal
Volume815
Issue number2
DOIs
StatePublished - Dec 20 2015

Bibliographical note

Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved.

Funding

FundersFunder number
National Science Foundation Arctic Social Science Program1312764, 1313171, 1055081, 1312547, 1326120, 1312780

    Keywords

    • galaxies: evolution
    • galaxies: formation
    • galaxies: high-redshift
    • galaxies: star formation

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

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