SIGNALS and SITELLE: Massive stars and HII regions in nearby galaxies with imaging Fourier transform spectroscopy

点击翻译按钮获取中文摘要

In response to CFHT's recent Call for Large Programs (2018B - 2022A semesters), an internatioal team I co-lead submitted a proposal to make use of its Imaging Fourier Transform Spectrometer SITELLE's unique capabilities to conduct a detailed survey of star-forming regions in nearby galaxies. SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey with SITELLE, will be based on a volume-limited sample of local extended galaxies (D = 10 Mpc) that are actively forming massive stars. SIGNALS, which has been awarded 50 nights of CFHT time over the next 4 years, will provide the largest, most complete, and homogeneous database of spectroscopically and spatially resolved extragalactic HII regions ever assembled. This will enable us to study small-scale nebular physics and many other phenomena linked to massive star formation in galaxies at a mean spatial resolution of ~20 pc. As is, our sample includes 39 spiral and irregular galaxies. HII regions present a wide variety of characteristics: morphology (from compact to extended shell), mass (where the low luminosity regime is not very well sampled), metallicity (where the rare metal-poor regions have been less studied), or age (following the diversity of their young stellar populations). They may be located in different galactic ecosystems and coexist with other sources of ionization (like shocks and AGN). The volume-limited sample will provide a statistically reliable laboratory, with over 50 000 resolved HII regions. By studying the spectra of spatially-resolved individual HII regions and their massive star content, SIGNALS aims at understanding how diverse local environments (nearby stellar population mass and age, gas density and chemical composition, dynamical structures, etc.) affect the star formation process. The legacy of our survey will reflect on many topics in astrophysics, from stars to very distant galaxies. Our primary immediate goals are to : 1) Quantify the impact of the near surrounding environment on the star formation process, 2) Link the feedback processes to the small-scale chemical enrichment and dynamics around star-forming regions, and 3) Measure variations of the resolved star formation rate with respect to indicators used for high-redshift galaxies. As PI of SITELLE and one of the five co-PIs of SIGNALS, I intend to devote most of my research time during the next five years to this Large Program. On the instrument side, I will play a leading role in the data reduction and quality assessment, software development and observational strategy, which will all likely evolve over the course of the survey. On the astronomical side, I will take this opportunity to come back to my main motivations behind the development of the imaging FTS technology, namely to study the influence of massive stars (and their core-collapse supernova descendants) on the kinematics and chemical enrichment of their immediate surroundings.