The H II Regions of the SIGNALS’ galaxy NGC 4395

Mykola Posternak ( Université Laval )

Generations of stars with changing properties shape the appearance of galaxies and mark the passage of time with clues about the different mechanism influencing star formation and galaxy evolution. A detailed study of HII regions, the ionized gas surrounding young star forming regions, is thus a key component for understanding galaxies. NGC 4395 was observed with SITELLE, the imaging Fourier transform spectrograph (IFTS) at the Canada-France-Hawaii Telescope, as part of SIGNALS. This survey aims to investigate over 50 000 spectroscopically and spatially resolved H II regions in approximately 40 nearby star-forming galaxies, enabling a detailed study of the small-scale physics of star-forming regions. Located at a distance of 4.3 Mpc, NGC 4395 is an isolated nearby dwarf galaxy which hosts a Sy1 type AGN with multiple star forming regions in asymmetric spiral arms. The impact of the stellar populations, gas chemical and dynamical state, and central black hole activity of NGC 4395 on its history has not yet been studied in detail. We present here preliminary results for the HII regions of NGC 4395. Using the strong emission lines seen in the visible with SITELLE, more than 1000 HII regions are detected over the whole galaxy disk. An emphasis is put on the emission regions’ detection code optimized for SIGNALS/SITELLE galaxies. BPT diagnostic diagrams and the gas kinematic and metallicity gradient are shown for NGC 4395. This analysis will help us to better understand the mechanisms responsible for the galaxy asymmetric morphology and its star formation history.