C Gruppioni (7774145)

E V Tollestrup (16104353)

H Crockett (16104350)

M Rowan-Robinson (7755881)

P Väisänen (16104347)

S Serjeant (16057889)

Seb Oliver (4460809)

T Morel (7717517)

T Sumner (16066562)

arXiv

Sussex Research Online

Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields

P. Vaisanen

T. Morel

M. Rowan-Robinson

S. Serjeant

S. Oliver

T. Sumner

H. Crockett

C. Gruppioni

E. V. Tollestrup

Crossref

We present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey (ELAIS) and study their classification and star-forming properties. We have used the Preliminary ELAIS Catalogue for the 6.7-mum (LW2) and 15-mum (LW3) fluxes. All of the high-reliability LW2 sources and 80 per cent of the LW3 sources are identified in the near-IR survey reaching K~ 17.5 mag. The near-IR/mid-IR flux ratios can effectively be used to separate stars from galaxies in mid-IR surveys. The stars detected in our survey region are used to derive a new accurate calibration for the ELAIS ISOCAM data in both the LW2 and LW3 filters. We show that near- to mid-IR colour-colour diagrams can be used to classify galaxies further, as well as to study star formation. The ELAIS ISOCAM survey is found mostly to detect strongly star-forming late-type galaxies, possibly starburst-powered galaxies, and it also picks out obscured active galactic nuclei. The ELAIS galaxies yield an average mid-IR flux ratio LW2/LW3 = 0.67 +/- 0.27. We discuss the fnu(6.7 mu m)/fnu(15 mu m) ratio as a star formation tracer using ISO and IRAS data of a local comparison sample. We find that the fnu(2.2 mu m)/fnu(15 mu m) ratio is also a good indicator of activity level in galaxies and conclude that the drop in the fnu(6.7 mu m)/fnu(15 mu m) ratio seen in strongly star-forming galaxies is a result of both an increase of 15-mum emission and an apparent depletion of 6.7-mum emission. Near-IR together with the mid-IR data make it possible to estimate the relative amount of interstellar matter in the galaxies

Väisänen, P.

Morel, T.

Rowan-Robinson, M.

Serjeant, S.

Oliver, S.

Sumner, T.

Crockett, H.

Gruppioni, C.

Tollestrup, E.V.

Open Research Online (Open)

English

peer reviewedWe present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey (ELAIS) and study their classification and star-forming properties. We have used the Preliminary ELAIS Catalogue for the 6.7-Î¼m (LW2) and 15-Î¼m (LW3) fluxes. All of the high-reliability LW2 sources and 80 per cent of the LW3 sources are identified in the near-IR survey reaching K~ 17.5 mag. The near-IR/mid-IR flux ratios can effectively be used to separate stars from galaxies in mid-IR surveys. The stars detected in our survey region are used to derive a new accurate calibration for the ELAIS ISOCAM data in both the LW2 and LW3 filters. We show that near- to mid-IR colour-colour diagrams can be used to classify galaxies further, as well as to study star formation. The ELAIS ISOCAM survey is found mostly to detect strongly star-forming late-type galaxies, possibly starburst-powered galaxies, and it also picks out obscured active galactic nuclei. The ELAIS galaxies yield an average mid-IR flux ratio LW2/LW3 = 0.67 +/- 0.27. We discuss the f[SUB]Î½[/SUB](6.7 Î¼ m)/f[SUB]Î½[/SUB](15 Î¼ m) ratio as a star formation tracer using ISO and IRAS data of a local comparison sample. We find that the f[SUB]Î½[/SUB](2.2 Î¼ m)/f[SUB]Î½[/SUB](15 Î¼ m) ratio is also a good indicator of activity level in galaxies and conclude that the drop in the f[SUB]Î½[/SUB](6.7 Î¼ m)/f[SUB]Î½[/SUB](15 Î¼ m) ratio seen in strongly star-forming galaxies is a result of both an increase of 15-Î¼m emission and an apparent depletion of 6.7-Î¼m emission. Near-IR together with the mid-IR data make it possible to estimate the relative amount of interstellar matter in the galaxies

Vaisanen, Petri

Morel, Thierry

Tollestrup, E. V.

Open Repository and Bibliography - Liège

Monthly Notices of the Royal Astronomical Society

A&A, 328, L9 Va¨isa¨nen

The ISO Handbook Volume III: CAM – The ISO Camera, http://www.iso.vilspa.esa.es/

Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields

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Sussex Research Online

Crossref

Open Research Online (Open)

Open Repository and Bibliography - Liège