Kavli Affiliate: Michael McDonald
| First 5 Authors: Benjamin Vigneron, Julie Hlavacek-Larrondo, Carter Lee Rhea, Marie-Lou Gendron-Marsolais, Jeremy Lim
| Summary:
We present new high-spectral resolution observations (R =
$lambda/Deltalambda$ = 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 (CFHT) with a field of view of $11text{
arcmin }times 11 text{ arcmin}$ encapsulating the entire filamentary
structure of ionised gas despite its large size of $80 text{ kpc}times50
text{ kpc}$. Here, we present renewed flux, velocity and velocity dispersion
maps that show in great detail the kinematics of the optical nebula at
sii$lambda6716$, sii$lambda6731$, nii$lambda6584$, H$alpha$(6563AA),
and nii$lambda6548$. These maps reveal the existence of a bright flattened
disk-shaped structure in the core extending to r $sim 10$ kpc and dominated by
a chaotic velocity field. This structure is located in the wake of X-ray
cavities and characterised by a high mean velocity dispersion of $134$ km/s.
The disk-shaped structure is surrounded by an extended array of filaments
spread out to $rsim 50$ kpc that are 10 times fainter in flux, remarkably
quiescent and has a uniform mean velocity dispersion of $44$ km/s. This
stability is puzzling given that the cluster core exhibits several energetic
phenomena. Based on these results, we argue that there are two mechanisms to
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 spread
throughout the core.
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