The local radio-ir relation in M51

Dumas G.; Schinnerer E.; Tabatabaei F.S.Beck R.Velusamy T.Murphy E.

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The local radio-ir relation in M51

机译：The local radio-ir relation in M51

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We observed M51 at three frequencies, 1.4 GHz (20 cm), 4.9 GHz (6 cm), and 8.4 GHz (3.6 cm), with the Very Large Array and the Effelsberg 100 m telescope to obtain the highest quality radio continuum images of a nearby spiral galaxy. These radio data were combined with deconvolved Spitzer IRAC 8 μm and MIPS 24 μm images to search for and investigate local changes in the radio-IR correlation. Utilizing wavelet decomposition, we compare the distribution of the radio and IR emission on spatial scales between 200 pc and 30 kpc. We show that the radio-IR correlation is not uniform across the galactic disk. It presents a complex behavior with local extrema corresponding to various galactic structures, such as complexes of Hii regions, spiral arms, and interarm filaments, indicating that the contribution of the thermal and non-thermal radio emission is a strong function of environment. In particular, the relation of the 24 μm and 20 cm emission presents a linear relation within the spiral arms and globally over the galaxy, while it deviates from linearity in the interarm and outer regions as well in the inner region, with two different behaviors: it is sublinear in the interarm and outer region and overlinear in the central 3.5 kpc. Our analysis suggests that the changes in the radio/IR correlation reflect variations of interstellar medium properties between spiral arms and interarm region. The good correlation in the spiral arms implies that 24 μm and 20 cm are tracing recent star formation, while a change in the dust opacity, "Cirrus" contribution to the IR emission and/or the relation between the magnetic field strength and the gas density can explain the different relations found in the interarm, outer, and inner regions.

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《The Astronomical journal》 |2011年第2期|41-1-41-19|共19页
作者
Dumas G.; Schinnerer E.; Tabatabaei F.S.Beck R.Velusamy T.Murphy E.;
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作者单位

Max-Planck-Institut für Astronomie, K?nigstuhl 17, D-69117 Heidelberg, Germany;

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany;

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, United StatesSpitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125, United States;

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原文格式 PDF
正文语种英语
中图分类天文学;
关键词
Galaxies; Galaxies: Individual (M51a; NGC5194); Galaxies: ISM; Infrared: Galaxies; Radio continuum;

The local radio-ir relation in M51

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