Query : 2008A&A...483...71M

2008A&A...483...71M - Astronomy and Astrophysics, volume 483, 71-78 (2008/5-3)

Soft X-ray to far infrared luminosities ratio in star-forming galaxies: predictions from synthesis models.


Abstract (from CDS):

A good correlation has been found in star-forming galaxies, between the soft X-ray and the far infrared or radio luminosities. The soft X-ray emission in star-forming regions is driven by the heating of the diffuse interstellar medium, and by the mechanical energy released by stellar winds and supernova explosions, both directly linked to the strength of the star formation episode. We analyze the relation between the soft X-ray and far infrared luminosities as predicted by evolutionary population synthesis models, aiming first to test the validity of the soft X-ray luminosity as a star formation rate estimator, using the already known calibration of the FIR luminosity as a proxy, and second to propose a calibration based on the predictions of evolutionary synthesis models. We have computed the soft X-ray and far infrared luminosities expected for a massive starburst as a function of evolutionary state, the efficiency of the conversion of mechanical energy into soft X-ray luminosity, the star formation history (instantaneous or extended) and dust abundance, and we have compared these predictions with observational values for 62 star-forming galaxies taken from the literature. The observational L_soft X/LFIR_ ratios are consistent with the model predictions under realistic assumptions (young starbursts, and efficiency in the re-processing of mechanical energy of a few percent), confirming the correlation between the diffuse soft X-ray emission and the star formation episode. The soft X-ray emission of the diffuse, extended gas surrounding massive star-forming regions, can be used as a star formation rate tracer. The empirical calibrations presented in the literature are supported by the predictions of evolutionary synthesis models, and by the analysis of a larger number of star-forming galaxies. The calibrations are, however, biased towards galaxies dominated by relatively unevolved starbursts.

Abstract Copyright:

Journal keyword(s): ISM: kinematics and dynamics - ISM: supernova remnants - galaxies: starburst - X-rays: galaxies - X-rays: ISM

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 NAME Chandra Deep Field-South reg 03 32 28.0 -27 48 30           ~ 2075 1
2 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 17261 1
3 M 82 AGN 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5814 6
4 Mrk 33 AG? 10 32 31.956 +54 24 03.53 13.29 13.66 13.13 12.71 12.27 ~ 363 1
5 NGC 4631 GiP 12 42 08.009 +32 32 29.44   9.78 9.19 9.10   ~ 1090 2
6 NGC 5253 AGN 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33 13.47 ~ 1358 4
7 NAME Local Group GrG ~ ~           ~ 8310 0

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