There’s an odd paradox impeding analysis into parts of the Milky Way. Thick gas limits observations of the galactic core and it can be challenging to view in visible light from Earth.
However, distant galaxies aren’t always like that. In some ways, we can view distant galaxies better than we can observe those near us. A team of astronomers utilized a telescope dubbed the Wisconsin H-Alpha Mapper (WHAM) to gain a better understanding of the Galactic Center (GC) and the Interstellar Medium (ISM). Here is what you should know.
Milky Way’s Features Analyzed
The team of astronomers focused on two features of the Milky Way, known as the Fermi Bubbles. The Fermi Bubbles are giant outbursts of high-energy gas arising from the galactic core. They’re named like that because they were initially found in 2010 by the Fermi Gamma-Ray Space Telescope. The bubbles are massive, extending a total of approximately 50,000 light-years from the disk of the Milky Way, and they’re flying at millions of miles/hour.
The observations made with WHAM display an intriguing approach. The telescope can spot Hydrogen-Alpha atoms. In such atoms, electrons have jumped from the third energy level to the second one. Such a thing indicates a spectral line that’s the brightest hydrogen spectral range in optical light.
“There are regions of the galaxy we can target with very sensitive instruments like WHAM to get this kind of new information toward the center that previously we were only able to do in the infrared and radio,” explained Matt Haffner, a professor of astronomy and physics at Embry-Riddle Aeronautical University.
The team also observed the nitrogen emission line in the Fermi Bubbles, and they added recent data from the Hubble Space Telescope of UV light in the same position. The two combined measurements of absorption and emission were applied to evaluate the pressure, density, and temperature of the ionized gas.
Astronomers believe that whatever happened at the Milky Way’s core to develop the Fermi Bubbles, occurred several millions of years ago. Some researchers think that Sgr A*, a supermassive black hole at the heart of the galaxy, brought a giant cloud of hydrogen into its accretion disk, triggering an immense burst of energy.