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摘要
This is the first paper of a series dedicated to nebular physics and the chemical evolution of nearby galaxies by investigating large samples of HII regions with the Canada-France-Hawaii Telescope imaging spectrograph SITELLE (Spectro-Imageur a Transformee de Fourier pour l'Etude en Long et en Large des raies d'Emission). We present a technique adapted to imaging spectroscopy to identify and extract parameters from 4285 H II region candidates found in the disc of NGC628. Using both the spatial and spectral capabilities of SITELLE, our technique enables the extraction of the position, dust extinction, velocity, H alpha profile, diffuse ionized gas (DIG) background, luminosity, size, morphological type, and the emission-line fluxes for individual spaxels and the integrated spectrum for each region. We have produced a well-sampled HII region luminosity function and studied its variation with galactocentric radius and level of the DIG background. We found a slope alpha of -1.12 +/- 0.03 with no evidence of a break at high luminosity. Based on the width of the region profile, bright regions are rather compact, while faint regions are seen over a wide range of sizes. The radius function reveals a slope of -1.81 +/- 0.02. BPT diagrams of the individual spaxels and integrated line ratios confirm that most detections are HII regions. Also, maps of the line ratios show complex variations of the ionization conditions within HII regions. All this information is compiled in a new catalogue for HII regions. The objective of this data base is to provide a complete sample which will be used to study the whole parameter space covered by the physical conditions in active star-forming regions.
- 出版日期2018-7
