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The spatially resolved correlation between [NII] 205μm line emission and the 24μm continuum in nearby galaxies

Hughes, T. M. and Baes, M. and Schirm, M. R. P. and Parkin, T. J. and Wu, R. and De Looze, I. and Wilson, C. D. and Viaene, S. and Bendo, G. J. and Boselli, A. and Cormier, D. and Ibar, E. and Karczewski, O. Ł. and Lu, N. and Spinoglio, L. (2016) The spatially resolved correlation between [NII] 205μm line emission and the 24μm continuum in nearby galaxies. Astronomy and Astrophysics, 587 . Art. No. A45. ISSN 0004-6361.

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A correlation between the 24 μm continuum and the [Nii] 205 μm line emission may arise if both quantities trace the star formation activity on spatially-resolved scales within a galaxy, yet has so far only been observed in the nearby edge-on spiral galaxy NGC 891. We therefore assess whether the [Nii] 205−24 μm emission correlation has some physical origin or is merely an artefact of line-of-sight projection effects in an edge-on disc. We search for the presence of a correlation in Herschel and Spitzer observations of two nearby face-on galaxies, M 51 and M 83, and the interacting Antennae galaxies NGC 4038 and 4039. We show that not only is this empirical relationship also observed in face-on galaxies, but also that the correlation appears to be governed by the star formation rate (SFR). Both the nuclear starburst in M 83 and the merger-induced star formation in NGC 4038/9 exhibit less [Nii] emission per unit SFR surface density than the normal star-forming discs. These regions of intense star formation exhibit stronger ionization parameters, as traced by the 70/160 μm far-infrared (FIR) colour. These observations suggest the presence of higher ionization lines that may become more important for gas cooling, thereby reducing the observed [Nii] 205 μm line emission in regions with higher star formation rates. Finally, we present a general relation between the [Nii] 205 μm line flux density and SFR density for normal star-forming galaxies, yet note that future studies should extend this analysis by including observations with wider spatial coverage for a larger sample of galaxies.

Item Type:Article
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URLURL TypeDescription DOIArticle Paper
Wilson, C. D.0000-0001-5817-0991
Lu, N.0000-0002-8948-1044
Additional Information:© 2016 ESO. Received 26 October 2015. Accepted 30 December 2015. We thank the anonymous referee for the useful comments and suggestions that helped to improve this paper. T.M.H. and E.I. acknowledge CONICYT/ALMA funding Program in Astronomy/PCI Project N°:31140020. T.M.H. also acknowledges the financial support from the Belgian Science Policy Office (BELSPO) in the frame of the PRODEX project C90370 (Herschel-PACS Guaranteed Time and Open Time Programs: Science Exploitation). M.B. and I.D.L. acknowledge the financial support of the Flemish Fund for Scientific Research (FWO-Vlaanderen). SPIRE was developed by a consortium of institutes led by Cardiff University (UK) and including Univ. Lethbridge (Canada); NAOC (China); CEA, LAM (France); IFSI, Univ. Padua (Italy); IAC (Spain); Stockholm Observatory (Sweden); Imperial College London, RAL, UCL-MSSL, UKATC, Univ. Sussex (UK); and Caltech, JPL, NHSC, Univ. Colorado (USA). This development has been supported by national funding agencies: CSA (Canada); NAOC (China); CEA, CNES, CNRS (France); ASI (Italy); MCINN (Spain); SNSB (Sweden); STFC, UKSA (UK); and NASA (USA). This research made use of APLpy, an open-source plotting package for Python hosted at
Funding AgencyGrant Number
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)31140020
Belgian Science Policy Office (BELSPO) PRODEXC90370
Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO)UNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
National Astronomical Observatories of ChinaUNSPECIFIED
Commissariat à l’Energie Atomique (CEA)UNSPECIFIED
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
Ministerio de Ciencia e Innovación (MCINN)UNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
United Kingdom Space Agency (UKSA)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Subject Keywords:galaxies: star formation, galaxies: spiral, galaxies: ISM, infrared: galaxies, ISM: lines and bands
Record Number:CaltechAUTHORS:20160503-111923243
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Official Citation:The spatially resolved correlation between [NII] 205 μm line emission and the 24 μm continuum in nearby galaxies T. M. Hughes, M. Baes, M. R. P. Schirm, T. J. Parkin, R. Wu, I. De Looze, C. D. Wilson, S. Viaene, G. J. Bendo, A. Boselli, D. Cormier, E. Ibar, O. Ł. Karczewski, N. Lu and L. Spinoglio A&A, 587 (2016) A45 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66619
Deposited By: Ruth Sustaita
Deposited On:03 May 2016 18:42
Last Modified:09 Mar 2020 13:19

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