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The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star-forming Galaxies from z ~ 1 to z ~ 3

Rafelski, Marc and Gardner, Jonathan P. and Fumagalli, Michele and Neeleman, Marcel and Teplitz, Harry I. and Grogin, Norman and Koekemoer, Anton M. and Scarlata, Claudia (2016) The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star-forming Galaxies from z ~ 1 to z ~ 3. Astrophysical Journal, 825 (2). Art. No. 87. ISSN 0004-637X.

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Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in damped Lyα systems (DLAs) at z ~ 3 is more than 10 times lower than predicted by the Kennicutt–Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galaxy properties, we measure the SFR efficiency of atomic gas at z ~ 1, z ~ 2, and z ~ 3 around star-forming galaxies. We use new robust photometric redshifts in the Hubble Ultra Deep Field to create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies' outskirts. We find that the SFR efficiency of H I gas at z > 1 is ~1%–3% of that predicted by the KS relation. Contrary to simulations and models that predict a reduced SFR efficiency with decreasing metallicity and thus with increasing redshift, we find no significant evolution in the SFR efficiency with redshift. Our analysis instead suggests that the reduced SFR efficiency is driven by the low molecular content of this atomic-dominated phase, with metallicity playing a secondary effect in regulating the conversion between atomic and molecular gas. This interpretation is supported by the similarity between the observed SFR efficiency and that observed in local atomic-dominated gas, such as in the outskirts of local spiral galaxies and local dwarf galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rafelski, Marc0000-0002-9946-4731
Fumagalli, Michele0000-0001-6676-3842
Neeleman, Marcel0000-0002-9838-8191
Teplitz, Harry I.0000-0002-7064-5424
Koekemoer, Anton M.0000-0002-6610-2048
Scarlata, Claudia0000-0002-9136-8876
Additional Information:© 2016 The American Astronomical Society. Received 2016 February 3; revised 2016 April 27; accepted 2016 April 27; published 2016 July 6. We would like to thank Rachel Somerville, Mark Krumholz, and Bruce Elmegreen for useful discussions on interpreting the results. We also thank the referee for useful comments that improved the clarity of the paper. M.R. acknowledges support from an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center. M.F. acknowledges support by the Science and Technology Facilities Council (grant number ST/L00075X/1). Support for HST Program GO-12534 was provided by NASA through grants from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Facilities: HST (WFC/ACS, WFC3/UVIS, WFC3/IR).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Postdoctoral ProgramUNSPECIFIED
Science and Technology Facilities Council (STFC)ST/L00075X/1
Subject Keywords:galaxies: evolution – galaxies: high-redshift – galaxies: photometry – galaxies: star formation – galaxies: structure – quasars: absorption lines
Issue or Number:2
Record Number:CaltechAUTHORS:20160916-155824076
Persistent URL:
Official Citation:Marc Rafelski et al 2016 ApJ 825 87
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70411
Deposited By: Tony Diaz
Deposited On:20 Sep 2016 15:05
Last Modified:09 Mar 2020 13:18

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