Using SITELLE, a unique camera mounted on the Canada-France-Hawaii Telescope (CFHT), four astrophysicists have revealed for the first time the highly complex dynamics of the galaxy NGC 1275.
Using SITELLE, a unique camera mounted on the Canada-France-Hawaii Telescope (CFHT), four researchers from the Center for Research in Astrophysics of Quebec (CRAQ), along with PhD student Marie-Lou Gendron-Marsolais and Professor Julie Hlavacek-Larrondo of Université de Montréal and Professor Laurent Drissen and postdoctoral researcher Thomas Martin of Université Laval, have revealed for the first time the highly complex dynamics of the galaxy NGC 1275.
Located 250 million light-years away from Earth, NGC 1275 is a galaxy like no other. It sits in the middle of the Perseus galaxies, a gigantic cluster harboring thousands of galaxies in the constellation of the same name. NGC 1275 is immersed in a hot, diffuse intra-cluster gas with an average temperature of tens of millions of degrees, a gas that forms most of the luminous mass of galaxy clusters. This environment is very complex: on the one hand, the hot gas tends to cool and fall towards the galaxy, but on the other, the central supermassive black hole produces powerful jets of very energetic particles, visible in the radio domain of electromagnetic waves; they blow gigantic bubbles into the hot gas, preventing it from cooling completely.
A spectacular network of intricate thin filaments surrounding NGC 1275 is visible at very specific wavelengths. "We often see these types of filaments around galaxies that lie in similar environments ... but their origin is a real mystery," said UdeM's Gendron-Marsolais.
Extending 250,000 light-years, about two-and-a-half times the size of our own galaxy, the network of filaments connecting this large nebula to its environment is still very poorly understood. Two hypotheses have been suggested: they could be filaments condensing from the hot intra-cluster gas sinking towards the center of the galaxy, or they could be gas lifted by the bubbles created by the central supermassive black hole jets and driven out of the galaxy.
To unravel the mystery of these filaments, the international team of researchers came up with the idea of using SITELLE, which is able to map the galaxy at several different wavelengths simultaneously. "You get a spectrum for each pixel in the image," said Professor Hlavacek-Larrondo. "But what's unique about SITELLE is its vast field of view, covering the whole area surrounding NGC1275 for the first time since this nebula was discovered 60 years ago." Mounted on the CFHT atop Mauna Kea on Hawaii's Big Island since 2015, SITELLE is funded by the Canadian Foundation for Innovation and is the result of a collaboration between CFHT, the high-performance technology company ABB, Université de Montréal and Université Laval, under the scientific supervision of Professor Laurent Drissen.
With SITELLE, the researchers were able to measure the radial velocity (the speed along their line of sight) of each of NGC 1275's filaments, revealing their dynamics in exceptional detail. "It seems that the movement of this network of filaments is very complex; there does not seem to be any uniform movement; it is extremely chaotic," said Gendron-Marsolais. The dynamics of these filaments can best be understood by studying the processes of heating and cooling of the gas that feeds the central black hole, the researchers believe. This understanding is also key to the study of galaxy evolution and, on a larger scale, environments such as clusters of galaxies.
About this study
The results of the research by Gendron-Marsolais, Hlavacek-Larrondo, Drissen, Martin and their international collaborators appear in a letter of the latest issue of the Monthly Notices of the Royal Astronomical Society.
A video showing the filaments structure as a function of wavelength can also be viewed.