Ferkinhoff, Carl and Brisbin, Drew and Nikola, Thomas and Parshley, Stephen C. and Stacey, Gordon J. and Phillips, Thomas G. and Falgarone, Edith and Benford, Dominic J. and Staguhn, Johannes G. and Tucker, Carol E. (2011) First Detections of the [N II] 122 μm Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe. Astrophysical Journal Letters, 740 (1). Art. No. L29. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20111014-150442996
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We report the first detections of the [N II] 122 μm line from a high-redshift galaxy. The line was strongly (>6σ) detected from SMMJ02399–0136, and H1413+117 (the Cloverleaf QSO) using the Redshift (z) and Early Universe Spectrometer on the Caltech Submillimeter Observatory. The lines from both sources are quite bright with line to far-infrared (FIR) continuum luminosity ratios that are ~7.0 × 10^(–4) (Cloverleaf) and 2.1 × 10^(–3) (SMMJ02399). With ratios 2-10 times larger than the average value for nearby galaxies, neither source exhibits the line-to-continuum deficits seen in nearby sources. The line strengths also indicate large ionized gas fractions, ~8%-17% of the molecular gas mass. The [O III]/[N II] line ratio is very sensitive to the effective temperature of ionizing stars and the ionization parameter for emission arising in the narrow-line region (NLR) of an active galactic nucleus (AGN). Using our previous detection of the [O III] 88 μm line, the [O III]/[N II] line ratio for SMMJ02399–0136 indicates that the dominant source of the line emission is either stellar H II regions ionized by O9.5 stars, or the NLR of the AGN with ionization parameter log(U) = –3.3 to –4.0. A composite system, where 30%-50% of the FIR lines arise in the NLR also matches the data. The Cloverleaf is best modeled by a superposition of ~200 M82-like starbursts accounting for all of the FIR emission and 43% of the [N II] line. The remainder may come from the NLR. This work demonstrates the utility of the [N II] and [O III] lines in constraining properties of the ionized medium.
|Additional Information:||© 2011 American Astronomical Society. Received 2011 June 24; accepted 2011 September 7; published 2011 September 22. This work was supported by NSF grants AST-00736289 and AST-0722220, and NASA grant NNX10AM09H. We thank the CSO staff for their support of ZEUS operations and the anonymous reviewer for their helpful comments.|
|Subject Keywords:||galaxies: active; galaxies: high-redshift; galaxies: individual (SMMJ02399-136, H1413+117); galaxies: starburst; submillimeter: galaxies|
|Classification Code:||PACS: 98.62.Py; 98.54.Ep; 98.62.Js; 98.54.Cm|
|Official Citation:||First Detections of the [N II] 122 μm Line at High Redshift: Demonstrating the Utility of the Line for Studying Galaxies in the Early Universe Carl Ferkinhoff et al. 2011 ApJ 740 L29|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||14 Oct 2011 22:40|
|Last Modified:||26 Dec 2012 14:16|
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