The first paper of the SIGNALS project has been published in the Monthly Notices. Led by PI Laurie Rousseau-Nepton, the paper demonstrates how the SIGNALS collaboration will identify and extract HII regions by focusing on the star-forming galaxy NGC 628 (M74). They managed to measure positions, dust extinctions, velocities, Hα profiles, diffuse ionized gas background, luminosities, sizes, morphological types, and emission-line fluxes for 4,285 HII regions.
Using both individual spaxels and integrated spectra for each region, they produced an HII region luminosity function with no evidence of a break at high luminosities. Additionally, maps of the line ratios show complex variations of the ionization conditions within HII regions.
Image: SITELLE’s deep image of NGC 628. For each pixel, the information from the three filters was summed together along with the Hα intensity map. Adding the Hα map highlights the ionized gas emission regions (in red on the image). North is up and east is left.
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