The Massive Magellanic Cloud is a small galaxy, only a tenth of the Milky Method’s mass. It’s about 160,000 mild years away, which is remarkably shut in cosmic phrases. Within the southern hemisphere it spans the width of 20 Moons within the evening sky. Whereas the galaxy appears timeless and unchanging to our quick human lives, it’s, the truth is, a dynamic system present process a close to collision with our galaxy. Now astronomers are starting to look at that course of.
The LMC is uncommon for a dwarf galaxy as a result of it’s unusually dense. Based mostly on stellar movement inside the LMC, it seems to have a moderately small halo surrounding it. This has led some astronomers to argue that the galaxy will not be in orbit across the Milky Method. As an alternative, it’s merely passing our galaxy, having made its closest method. Because the galaxy handed via the massive and comparatively dense halo of the Milky Method, a number of the LMC halo would have been stripped away, trailing behind it in a diffuse tail. It’s a probable state of affairs, however proving it has been a tough problem. The halo of the Massive Magellanic Cloud is simply too darkish and diffuse for us to look at immediately. However this new research has lastly noticed the LMC halo due to some distant quasars.
Quasars are highly effective beacons powered by supermassive black holes in distant galaxies. Although they’re billions of light-years away, their mild could be simply noticed by radio telescopes and area telescopes such because the Hubble. Utilizing Hubble information, the group appeared for quasars in areas the place the LMC halo was more likely to be. On this approach, the sunshine of these quasars would move via the halo earlier than reaching us, and a number of the quasar mild can be absorbed by the halo. By measuring the spectra of 28 quasars within the LMC sky area, the group was in a position to make the primary mapping of the small galaxy’s halo. Assuming the LMC had a big halo much like different small galaxies earlier than its flyby of the Milky Method, the group estimates that the LMC has solely held on to about 10% of its unique halo. The remainder of the halo now streams behind the galaxy like a comet’s tail, although that has but to be noticed.
Sooner or later, the group wish to use extra quasars to additional map the LMC halo, notably within the entrance area the place the halo is immediately colliding with that of the Milky Method. Such work will assist us higher perceive what occurs when galaxies work together and the way that may have an effect on the evolution of these galaxies.
Reference: Mishra, Sapna, et al. “The Truncated Circumgalactic Medium of the Massive Magellanic Cloud.” arXiv preprint arXiv:2410.11960 (2024).
