NGC 925 with SITELLE: HII region analysis

Ionized gas is a key component for understanding star formation within galaxies. As part of SIGNALS, a survey that focuses on the emission regions of about 40 nearby star-forming galaxies, NGC 925 was observed with SITELLE, an imaging Fourier transform spectrometer for the optical spectrum built in Qúebec City (U. Laval and ABB) and installed at the Canada-France-Hawaii Telescope. This work mainly focuses on HII regions; establishing the physical characteristics of these regions will yield reliable insight regarding the influence of local environments on star formation and the different star-forming mechanisms at play. At a distance of 9.2 Mpc, NGC 925 is a fine candidate in SIGNALS framework, due to SITELLE's high spatial resolution of 0.32"/pixel and large field of view of 11'x11', HII regions are differentiated from one another over the whole galaxy. Using Hα to locate emission regions, we compute BPT diagrams for these regions using the emission line ratios [OIII]/Hβ and [NII]/Hα. A catalog of HII regions is compiled from these diagrams. The preliminary results presented in this work (i.e., a young bar, an asymmetric distribution of HII regions and recent star formation) suggest that NGC 925 may be the result of an interaction with another member of NGC 1023 group. Simulations of galaxy interactions and multiwavelength observations will be acquired to confirm this hypothesis.