ESA's XMM-Newton has discovered that gas lurking within the Milky Way's halo reaches far hotter temperatures than previously thought and has a different chemical make-up than predicted, challenging our understanding of our galactic home.
A halo is a vast region of gas, stars and invisible dark matter surrounding a galaxy. It is a key component of a galaxy, connecting it to wider intergalactic space, and is thus thought to play an important role in galactic evolution.
Galaxy - Halo - Gas - Temperature - Temperature
Until now, a galaxy's halo was thought to contain hot gas at a single temperature, with the exact temperature of this gas dependent on the mass of the galaxy.
However, a new study using ESA's XMM-Newton X-ray space observatory now shows that the Milky Way's halo contains not one but three different components of hot gas, with the hottest of these being a factor of ten hotter than previously thought. This is the first time multiple gas components structured in this way have been discovered in not only the Milky Way, but in any galaxy.
Gas - Temperatures - Halos - Degrees—but - Gas
"We thought that gas temperatures in galactic halos ranged from around 10 000 to one million degrees—but it turns out that some of the gas in the Milky Way's halo can hit a scorching 10 million degrees," said Sanskriti Das, a graduate student at The Ohio State University, U.S., and lead author of the new study.
"While we think that gas gets heated to around one million degrees as a galaxy initially forms, we're not sure how this component got so hot. It may be due to winds emanating from the disc of stars within the Milky Way."
Study - Combination - Instruments - XMM-Newton - Reflection
The study used a combination of two instruments aboard XMM-Newton: the Reflection Grating Spectrometer (RGS) and European Photon Imaging Camera (EPIC). EPIC was used to study the light emitted by the halo, and RGS to study how...
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