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Investigating Hα, UV, and IR Star-formation Rate Diagnostics for a Large Sample of z ~ 2 Galaxies

Shivaei, Irene and Reddy, Naveen A. and Steidel, Charles C. and Shapley, Alice E. (2015) Investigating Hα, UV, and IR Star-formation Rate Diagnostics for a Large Sample of z ~ 2 Galaxies. Astrophysical Journal, 804 (2). Art. No. 149. ISSN 0004-637X.

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We use a sample of 262 spectroscopically confirmed star-forming galaxies at redshifts 2.08 ≤ z ≤ 2.51 to compare Hα, ultraviolet (UV), and IR star formation rate (SFR) diagnostics and to investigate the dust properties of the galaxies. At these redshifts, the Hα line shifts to the K_s band. By comparing K_s-band photometry to underlying stellar population model fits to other UV, optical, and near-infrared data, we infer the Hα flux for each galaxy. We obtain the best agreement between Hα- and UV-based SFRs if we assume that the ionized gas and stellar continuum are reddened by the same value and that the Calzetti attenuation curve is applied to both. Aided with MIPS 24 μm data, we find that an attenuation curve steeper than the Calzetti curve is needed to reproduce the observed IR/UV ratios of galaxies younger than 100 Myr. Furthermore, using the bolometric SFR inferred from the UV and mid-IR data (SFR_(IR)+SFR_(UV), we calculated the conversion between the Hα luminosity and SFR to be (7.5 ± 1.3) x 10^(-42) for a Salpeter initial mass function, which is consistent with the Kennicutt conversion. The derived conversion factor is independent of any assumption of the dust correction and is robust to stellar population model uncertainties.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Reddy, Naveen A.0000-0001-9687-4973
Steidel, Charles C.0000-0002-4834-7260
Shapley, Alice E.0000-0003-3509-4855
Additional Information:© 2015 American Astronomical Society. Received 2014 August 26; accepted 2015 March 12; published 2015 May 12. I.S. thanks Valentino González for useful discussions. Support for I.S. is provided through the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1326120. N.A.R. is supported by an Alfred P. Sloan Research Fellowship.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1326120
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: high-redshift; galaxies: star formation
Issue or Number:2
Record Number:CaltechAUTHORS:20150619-095300192
Persistent URL:
Official Citation:Investigating Hα, UV, and IR Star-formation Rate Diagnostics for a Large Sample of z ~ 2 Galaxies Irene Shivaei et al. 2015 ApJ 804 149
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58376
Deposited By: Ruth Sustaita
Deposited On:19 Jun 2015 18:17
Last Modified:03 Oct 2019 08:35

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