Free Access
 Issue A&A Volume 432, Number 2, March III 2005 423 - 429 Extragalactic astronomy https://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)

Abstract
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, (Helou et al. 1988), (Dale et al. 2001a), revised version of (Dale & Helou 2002) (we denote ), and (Sanders &Mirabel 1996) by using the observed SEDs of well-known galaxies. We found that provides excellent estimates of the total IR luminosity for a variety of galaxy SEDs. The performance of was also found to be very good. Using , we then statistically analyzed the IRAS PSCz galaxy sample (Saunders et al. 2000) and found useful formulae relating the MIR monochromatic luminosities [ and ] and  . For this purpose we constructed a subsample of 1420 galaxies with all four IRAS band (12, 25, 60, and m) flux densities. We found linear relations between and MIR luminosities, and . 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 m or 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-m luminosity and the total IR luminosity. We conclude that the 15-m formula can be used as an estimator of the total IR luminosity from m observation of galaxies at .

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