A spatially resolved study of ionized regions in galaxies at different ...

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68 3 • IFS of a GEHR in NGC 6946 Creating maps Maps are data files stored in 2D fits files, reflecting the original arrangement of the spaxels in the sky. In the case of non regularly gridded IFU or RSS files, it is necessary to interpolate the data, as mentioned in previous sections. We have used interpol routine from E3D with a nearest neighbour interpolation, a grid parameter 13 of 10 −12 and a pixel size of 1 ′′ , close to the recommended 1/3 of the original spaxel size. All the maps shown in next sections, unless mentioned, have a North down and East left orientation, and a 1 ′′ /pixel scale. A distance of 5.9 Mpc to NGC 6946 is assumed, so 1 ′′ in the sky corresponds to 28.6 pc. We have masked all values in the maps with relative errors ≥ 25%. This is applied to any quantity: flux, ratio or combination of lines used in empirical parameters. 3.4.3 Hα maps and morphology From Figure 3.14 it is clear that the morphology of the complex of Hii regions is well recovered from the IFU data. The upper panel is an Hα flux map created from the RSS blue data as explained in section 3.4.2. The masked values follow the criteria explained in that section, as well as the orientation (north down, east left). The lower panel shows an Hα (not continuum-subtracted) image taken at the Kitt Peak National Observatory (KPNO) 2.1-meter telescope (same source as Figure 3.3) showing the PPak field and with the same orientation as the map of the upper panel. Hodge and Kennicutt (1983) catalogued more than 10000 Hii regions in 125 galaxies. This HK catalog contains 540 identified Hii regions in NGC 6946. We have labelled all the important knots following the HK identification. As it can be seen in the Hα map, only the most intense knots are clearly defined, and for this reason we have labelled them with the first four alphabetical letters. Interestingly, knot B is not identified in Hodge and Kennicutt (1983). Since they have enough signal-to-noise, we will present the main measured properties of these four knots when discussing the integrated properties in section 3.4.8. It has to be remarked that the lower panel image has not been continuum-subtracted, so some knots are seen more intense since their continuum sources are included in the image, but their Hα emission are not so strong. This is the case of knots HK83-013, HK83-014, HK83-009 and HK83-006. Figure 3.15 shows the continuum emission near Hα (top) and Hβ (bottom) maps together with the corresponding emission line intensity isocontours overplotted, while Figure 3.16 shows the continuum emission map near 8500 Å together with the Hα isocontours overplotted as reference. The red continuum comes from the first pointing. Maps of the continua are representative of the stellar emission, free of contamination from the gaseous emission lines. From the Hα and Hβ isocontours it can be seen that both emission structures are 13 The grid parameter represents the resolution of the triangulation.
60¡DEC (arcsec) 3.4. Results 69 B C (HK83-004) HK83-005 60.0 50 A (HK83-003) D (HK83-016) 46.8 40 35.2 30 HK83-001 HK83-013 25.3 17.0 20 10.4 10 HK83-002 HK83-006 HK83-009 HK83-014+SN1948B 0 0 10 20 30 40 50 60 70 RA (arcsec) 5.4 2.0 −30 B HK83-004 HK83-005 −20 −10 HK83-003 HK83-016 30¢DEC (arcsec) 0 10 20 HK83-001 HK83-002 HK83-006 HK83-009 HK83-013 HK83-014+SN1948B −40 −30 −20 −10 0 10 20 30 40 ¡RA (arcsec) 74.00 ( 2.12 kpc) Figure 3.14: Upper panel: Hα flux map (not corrected for reddening) obtained from the IFU data. The scale bar (valid only for the upper panel) is given in units of 10 −16 erg s −1 cm −2 . North is down and east is left. The masked values follow the criteria explained in section 3.4.2. Lower panel: Hα image taken at the Kitt Peak National Observatory (KPNO) 2.1-meter telescope (same source as Figure 3.3). The image has not been continuum-subtracted. The hexagon shows the position of the PPak FOV. The orientation is the same as the image of the upper panel. The most important knots are labelled following the identification by Hodge and Kennicutt (1983). The four main intense knots are also labelled with the first alphabet letters. Knot B is not identified in Hodge and Kennicutt (1983).
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Facultad de Ciencias Departamento d
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A Abigaíl, mi ut A mi familia, por
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La gente del grupo de Astrofísica
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Contents List of Figures List of Ta
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CONTENTS iii B •Physical conditio
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vi LIST OF FIGURES 3.12 Example of
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List of Tables 1.1 Integrated prope
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Chapter 1 Introduction 1.1 Overview
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1.1. Overview 3 Figure 1.1: Sample
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1.1. Overview 5 These massive star
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1.1. Overview 7 Figure 1.3: Color-m
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1.2. Aims and structure of this wor
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12 2 • The star formation history
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118 4 • Long-slit spectrophotomet
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Table 4.4 continued SDSS J1657 Knot
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150 Conclusions and future work has
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152 Conclusions and future work oth
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154 Conclusions and future work The
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156 Conclusiones Las abundancias to
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158 Conclusiones consistentes con l
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160 Appendix A where c=0.434C. This
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162 Appendix B where R S2 = I(6717
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164 Appendix B Sulphur As in the ca
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166 Appendix B Argon For argon, the
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Appendix C Empirical calibrators In
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C • Empirical calibrators 171 One
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Appendix D Stellar photometry resul
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D • Stellar photometry results of
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190 REFERENCES Bertelli, G., Bressa
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192 REFERENCES Girardi, L. & Bertel
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194 REFERENCES Kunth, D. & Sargent,
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196 REFERENCES Pérez-Montero, E.,
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198 REFERENCES Terlevich, R., Melni
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