EDP Sciences
Free access
Volume 432, Number 2, March III 2005
Page(s) 423 - 429
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20042189

A&A 432, 423-429 (2005)
DOI: 10.1051/0004-6361:20042189

Mid-infrared luminosity as an indicator of the total infrared luminosity of galaxies

T. T. Takeuchi, V. Buat, J. Iglesias-Páramo, A. Boselli and D. Burgarella

Laboratoire d'Astrophysique de Marseille, Traverse du Siphon, BP8, 13376 Marseille Cedex 12, France
    e-mail: [tsutomu.takeuchi;veronique.buat;jorge.iglesias;alessandro.boselli; denis.brugarella]@oamp.fr

(Received 15 October 2004 / Accepted 2 November 2004)

The infrared (IR) emission plays a crucial role in understanding the star formation in galaxies hidden by dust. We first examined four estimators of the IR luminosity of galaxies, $L_{\rm FIR}$ (Helou et al. 1988), $L_{\rm TIR}$ (Dale et al. 2001a), revised version of $L_{\rm TIR}$ (Dale & Helou 2002) (we denote $L_{\rm TIR2}$), and $L_{\rm IR}$ (Sanders &Mirabel 1996) by using the observed SEDs of well-known galaxies. We found that $L_{\rm IR}$ provides excellent estimates of the total IR luminosity for a variety of galaxy SEDs. The performance of $L_{\rm TIR2}$ was also found to be very good. Using $L_{\rm IR}$, we then statistically analyzed the IRAS PSCz galaxy sample (Saunders et al. 2000) and found useful formulae relating the MIR monochromatic luminosities [ $L(12\,\mu\mbox{m})$ and $L(25\,\mu\mbox{m})$] and  $L_{\rm IR}$. For this purpose we constructed a subsample of 1420 galaxies with all four IRAS band (12, 25, 60, and $100\,\mu$m) flux densities. We found linear relations between $L_{\rm IR}$ and MIR luminosities, $L(12\,\mu\mbox{m})$ and $L(25\,\mu\mbox{m})$. The prediction error with a 95% confidence level is a factor of 4-5. Hence, these formulae are useful for the estimation of the total IR luminosity only from $12\,\mu$m or $25\,\mu$m observations. We further tried to make an "interpolation" formula for galaxies at 0<z<1. For this purpose we construct the formula of the relation between 15-$\mu$m luminosity and the total IR luminosity. We conclude that the 15-$\mu$m formula can be used as an estimator of the total IR luminosity from $24\,\mu$m observation of galaxies at $z \simeq 0.6$.

Key words: dust, extinction -- galaxies: statistics -- infrared: galaxies -- methods: statistical

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