Decarli, R. and Walter, F. and Neri, R. and Bertoldi, F. and Carilli, C. and Cox, P. and Kneib, J. P. and Lestrade, J. F. and Maiolino, R. and Omont, A. and Richard, J. and Riechers, D. and Thanjavur, K. and Weiss, A. (2012) Ionized Nitrogen at High Redshift. Astrophysical Journal, 752 (1). Art. No. 2. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120713-114801908
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We present secure [N II]_(205 μm) detections in two millimeter-bright, strongly lensed objects at high redshift, APM 08279+5255 (z = 3.911) and MM 18423+5938 (z = 3.930), using the IRAM Plateau de Bure Interferometer. Due to its ionization energy [N II]_(205 μm) is a good tracer of the ionized gas phase in the interstellar medium. The measured fluxes are S([N II]_(205 μm)) = (4.8 ± 0.8) Jy km s^(–1) and (7.4 ± 0.5) Jy km s^(–1), respectively, yielding line luminosities of L([N II]_(205 μm)) = (1.8 ± 0.3) × 10^9 μ^(–1) L_⊙ for APM 08279+5255 and L([N II]_(205 μm)) = (2.8 ± 0.2) × 10(^9) μ^(–1) L_⊙ for MM 18423+5938. Our high-resolution map of the [N II]_(205 μm) and 1 mm continuum emission in MM 18423+5938 clearly resolves an Einstein ring in this source and reveals a velocity gradient in the dynamics of the ionized gas. A comparison of these maps with high-resolution EVLA CO observations enables us to perform the first spatially resolved study of the dust continuum-to-molecular gas surface brightness (Σ_(FIR)α Σ^N_CO, which can be interpreted as the star formation law) in a high-redshift object. We find a steep relation (N = 1.4 ± 0.2), consistent with a starbursting environment. We measure a [N II]_(205 μm)/FIR luminosity ratio in APM 08279+5255 and MM 18423+5938 of 9.0 × 10^(–6) and 5.8 × 10^(–6), respectively. This is in agreement with the decrease of the [N II]_(205 μm)/FIR ratio at high FIR luminosities observed in local galaxies.
|Additional Information:||© 2012 The American Astronomical Society. Received 2011 December 21; accepted 2012 March 30; published 2012 May 18. We thank the anonymous referee for his/her expert comments that increased the quality of themanuscript.We thank B. Groves for useful discussions. This work is based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAMis supported by INSU/CNRS(France),MPG (Germany), and IGN (Spain). R.D. acknowledges funding from Germany’s National Research Centre for Aeronautics and Space (DLR, project FKZ 50 OR 1104). D.R. acknowledges support from NASA through a Spitzer Space Telescope grant.|
|Subject Keywords:||galaxies: individual (MM 18423+5938); galaxies: ISM; quasars: individual (APM 08279+5255)|
|Official Citation:||Ionized Nitrogen at High Redshift R. Decarli et al. 2012 ApJ 752 2|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Aucoeur Ngo|
|Deposited On:||13 Jul 2012 20:14|
|Last Modified:||26 Dec 2012 15:31|
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