Astronomy & Astrophysics

All Figures

$\begin{figure} \par {\includegraphics[width=8.8cm,clip]{f1_0002.ps} }\end{figure}$ Figure 1: Bandpasses of the MIR indicators of star formation activity. The transmission profiles of the ISOCAM LW2 and LW3 filters and the narrow band used for the monochromatic 15 $\mu$ m,ct continuum measurements are shown by the grey lines. To illustrate the typical spectral features covered by these bandpasses, the spectra of the starburst galaxy M 82 obtained at $R \sim 500{-}1000$ with the ISO SWS and at $R \sim 40$ with ISOCAM within the SWS field of view are plotted in the top and bottom panels, respectively (from Förster Schreiber et al. 2001,2003). Identifications of the emission features are labeled on the SWS spectrum.
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In the text

$\begin{figure} \par {\includegraphics[angle=90,width=8.8cm,clip]{f2_0002.ps} }\end{figure}$ Figure 2: Empirical relationship used to estimate the monochromatic 15 $\mu$ m continuum flux density from broadband LW2 and LW3 measurements. The black circles represent circumnuclear regions of spiral galaxies and starburst systems for which both broadband and CVF data are available. Diamonds represent galaxies with only CVF data, for which broadband fluxes were synthesized from the spectrum. The line shows the least-squares fit obtained as explained in the text, y = a - b / x, where x and y are the abscissa and the ordinate. The error bar indicates the mean and 1 $\sigma$ dispersion in $f_{\rm 12{-}18~\mu m}/f_{\rm 5{-}8.5~\mu m}$ color of the sample of spiral disks, and the $f_{\rm 15~\mu m,ct}/f_{\rm 12{-}18~\mu m}$ ratio and measurement uncertainty for the disk of NGC 5236. The disk of this galaxy was chosen because its spectrum has the highest signal-to-noise ratio of the sample.
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In the text

$\begin{figure} \par {\includegraphics[angle=90,width=8.8cm,clip]{f3_0002.ps} } \... ...m} \par {\includegraphics[angle=90,width=8.8cm,clip]{f4_0002.ps} }\end{figure}$ Figure 3: Empirical relationships between the MIR dust emission and the Lyman continuum luminosity as a measure of the star formation rate. The quantities plotted are size-normalized luminosities, with different symbols used for the spiral disks (crosses), and the circumnuclear regions of spirals and starburst systems (diamonds). a) In the $\log(\Sigma_{\rm 15~\mu m,ct}){-}\log(\Sigma_{\rm Lyc})$ diagram, the solid line indicates the power-law least-squares fit performed on the circumnuclear regions and starbursts only, excluding the disks, NGC 5194 and Arp 220. The short-dashed line shows the fit result where the index was fixed to unity, and the long-dashed line shows a similar fit for disks alone. b) In the $\log(\Sigma_{\rm 7~\mu m}){-}\log(\Sigma_{\rm Lyc})$ diagram, the conventions are the same and fits were performed including the disks, but excluding NGC 253, NGC 3034 (=M 82), NGC 6240 and Arp 220.
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In the text

$\begin{figure} \par {\includegraphics[angle=90,width=8.8cm,clip]{f5_0002.ps} }\end{figure}$ Figure 4: Evolution of the $L_{\rm 15~\mu m,ct}/L_{\rm 5{-}8.5~\mu m}$ ratio with increasing Lyman continuum luminosity per unit projected surface area. Apart from the disks, only galaxies with a CVF spectrum are shown here.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.8cm,clip]{f6_0002.ps} \end{figure}$ Figure B.1: Mid-infrared spectrum of IC 342 summed over the central $21\hbox {$^{\prime \prime }$ }\times 21\hbox {$^{\prime \prime }$ }$ . The error bars represent the uncertainty on the subtracted zodiacal foreground. Errors arising from imperfect signal stabilization are not included, but are likely important at $\lambda \geq 15.5~\mu$ m.

In the text

$\begin{figure} \par {\includegraphics[angle=90,width=8.8cm,clip]{f5_0002.ps} }\end{figure}$	Figure 4: Evolution of the $L_{\rm 15~\mu m,ct}/L_{\rm 5{-}8.5~\mu m}$ ratio with increasing Lyman continuum luminosity per unit projected surface area. Apart from the disks, only galaxies with a CVF spectrum are shown here.
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