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Correlation between star formation activity and electron density of ionized gas at z = 2.5

Shimakawa, Rhythm and Kodama, Tadayuki and Steidel, Charles C. and Tadaki, Ken-ichi and Tanaka, Ichi and Strom, Allison L. and Hayashi, Masao and Koyama, Yusei and Suzuki, Tomoko L. and Yamamoto, Moegi (2015) Correlation between star formation activity and electron density of ionized gas at z = 2.5. Monthly Notices of the Royal Astronomical Society, 451 (2). pp. 1284-1289. ISSN 0035-8711.

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In the redshift interval of 2 < z < 3, the physical conditions of the interstellar medium (ISM) in star-forming galaxies are likely to be different from those in the local Universe because of lower gaseous metallicities, higher gas fractions, and higher star formation activities. In fact, observations suggest that higher electron densities, higher ionization parameters, and harder UV radiation fields are common. In this paper, based on the spectra of H α-selected star-forming galaxies at z = 2.5 taken with Multi-Object Spectrometer for InfraRed Exploration on Keck-1 telescope, we measure electron densities (n_e) using the oxygen line ratio ([O II] λλ3726,3729), and investigate the relationships between the electron density of ionized gas and other physical properties. As a result, we find that the specific star formation rate (sSFR) and the surface density of SFR (Σ_(SFR)) are correlated with the electron density at z = 2.5 for the first time. The Σ_(SFR)–n_e relation is likely to be linked to the star formation law in H II regions (where star formation activity is regulated by interstellar pressure). Moreover, we discuss the mode of star formation in those galaxies. The correlation between sSFR and Σ_(SFR) suggests that highly star-forming galaxies (with high sSFR) tend to be characterized by higher surface densities of star formation (Σ_(SFR)) and thus higher n_e values as well.

Item Type:Article
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URLURL TypeDescription Paper
Steidel, Charles C.0000-0002-4834-7260
Strom, Allison L.0000-0001-6369-1636
Additional Information:© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 April 22. Received 2015 March 25. In original form 2014 November 5. First published online June 5, 2015. We are grateful to the anonymous referee for useful comments. The data presented in this paper were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Data analyses were in part carried out on common use data analysis computer system at the Astronomy Data Center, ADC, of the National Astronomical Observatory of Japan.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:galaxies: formation; galaxies: high-redshift; galaxies: ISM
Issue or Number:2
Record Number:CaltechAUTHORS:20151002-150103207
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Official Citation:Rhythm Shimakawa, Tadayuki Kodama, Charles C. Steidel, Ken-ichi Tadaki, Ichi Tanaka, Allison L. Strom, Masao Hayashi, Yusei Koyama, Tomoko L. Suzuki, and Moegi Yamamoto Correlation between star formation activity and electron density of ionized gas at z = 2.5 MNRAS (August 01, 2015) Vol. 451 1284-1289 doi:10.1093/mnras/stv915 First published online June 5, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60729
Deposited By: George Porter
Deposited On:02 Oct 2015 22:47
Last Modified:03 Oct 2019 09:00

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