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ABSTRACT We present a spatially resolved study of the kinematical properties of known supernova remnants (SNRs) in the nearest galaxies of the SIGNALS survey, namely NGC 6822 (one object) and M33 (163 objects), based on data obtained with the SITELLE imaging Fourier transform spectrometer at the Canada–France–Hawaii Telescope. The purpose of this paper is to provide a better scheme of identification for extragalactic SNRs and, in particular, to distinguish between H ii regions and SNRs. For that we have used diagrams which involve both the [S ii]/H$$\alpha$$ ratio and the velocity dispersion ($$\sigma$$). We also introduce a new parameter, $$\xi = {[\rm S\, {\small II}] \over H\alpha } \times \sigma$$, which enhances still the contrast between SNRs and the rest of the ionized gas. More than 90 per cent of the SNRs in our entire sample show an integrated [S ii]/H$$\alpha$$ ratio larger than the canonical value (0.4). 86 per cent of the SNRs present in our field show a significant velocity dispersion. The spectral resolution of our observations allows us to observe the complex velocity structure of some SNRs. 

Abstract We  present new high-spectral-resolution observations (R=λ/Δλ= 7000) of the filamentary nebula surrounding NGC 1275, the central galaxy of the Perseus cluster. These observations have been obtained with SITELLE, an imaging Fourier transform spectrometer installed on the Canada–France–Hawai Telescope with a field of view of $11\prime \times 11\prime$, encapsulating the entire filamentary structure of ionized gas despite its large size of 80 kpc × 50 kpc. Here, we present renewed fluxes, velocities, and velocity dispersion maps that show in great detail the kinematics of the optical nebula at [Sii]λ6716, [Sii]λ6731, [Nii]λ6584, Hα(6563 Å), and [Nii]λ6548. These maps reveal the existence of a bright flattened disk-shaped structure in the core extending tor∼10 kpc and dominated by a chaotic velocity field. This structure is located in the wake of X-ray cavities and characterized by a high mean velocity dispersion of 134 km s⁻¹. The disk-shaped structure is surrounded by an extended array of filaments spread out tor∼ 50 kpc that are 10 times fainter in flux, remarkably quiescent, and have a uniform mean velocity dispersion of 44 km s⁻¹. This stability is puzzling given that the cluster core exhibits several energetic phenomena. Based on these results, we argue that there are two mechanisms that form multiphase gas in clusters of galaxies: a first triggered in the wake of X-ray cavities leading to more turbulent multiphase gas and a second, distinct mechanism, that is gentle and leads to large-scale multiphase gas spreading throughout the core.