2023-05-09 23:35:25
Astronomers have revealed new evidence regarding the properties of giant bubbles of high-energy gas that stretch far above and below the center of the Milky Way galaxy.
In a study recently published innatural astronomya team led by scientists from Ohio State University was able to show that the shells of these structures – dubbed “eRosita bubbles” following being discovered by the eRosita X-ray telescope – are more complex than previously thought.
Although they bear a striking similarity in shape to Fermi bubbles, eRosita bubbles are larger and more energetic than their counterparts. Known collectively as “galactic bubbles” due to their size and location, they provide an exciting opportunity to study the history of star formation and reveal new clues regarding the birth of the Milky Way. said Anjali Gupta, lead author of the study and a former postdoctoral researcher at Ohio State who is now a professor of astronomy at Columbus State Community College.
These bubbles exist in the gas that surrounds galaxies, an area called the circumgalactic medium.
“Our goal was really to learn more regarding the circumgalactic medium, a very important place to understand how our galaxy formed and evolved,” Gupta said. “A lot of the regions we were studying were in the bubble region, so we wanted to see how different the bubbles were compared to the regions away from the bubble.”
Previous studies had assumed that these bubbles were heated by the gas shock as it blows outward from the galaxy, but the main findings of this paper suggest that the temperature of the gas inside the bubbles is not significantly different from the area outside.
“We were surprised to find that the temperature inside the bubble region and outside the bubble region was the same,” Gupta said. Moreover, the study demonstrates that these bubbles are so bright because they are filled with extremely dense gas, not because they are at higher temperatures than the surrounding medium.
Gupta and Smita Mathur, co-author of the study and professor of astronomy at Ohio State, made their analysis using observations made by the Suzaku satellite, a collaborative mission between NASA and the Japan Space Agency. aerospace exploration.
By analyzing 230 archival observations made between 2005 and 2014, the researchers were able to characterize the diffuse emission – the electromagnetic radiation of very low density gases – from the galactic bubbles, as well as from the other hot gases that surround them.
Although the origin of these bubbles has been debated in the scientific literature, this study is the first that begins to settle it, Mathur said. While the team found an abundance of non-solar neon-oxygen and magnesium-oxygen ratios in the shells, their findings strongly suggest that the galactic bubbles were originally formed by nuclear star-forming activity or by the injection of energy by massive stars and other types. astrophysical phenomena, rather than by the activities of a supermassive black hole.
“Our data supports the theory that these bubbles are most likely formed due to intense star-forming activity at the galactic center, as opposed to black hole activity occurring at the galactic center,” Mathur said. To further investigate the implications their discovery might have for other aspects of astronomy, the team hopes to use new data from other upcoming space missions to continue characterizing the properties of these bubbles, as well as work on new ways to analyze the data they already have. .
“Scientists really need to understand the formation of the bubble structure, so by using different techniques to improve our models, we can better constrain the temperature and emission measurements we’re looking for,” Gupta said.
Other co-authors were Joshua Kingsbury and Sanskriti Das from Ohio State and Yair Krongold from the National Autonomous University of Mexico. This work was supported by NASA.
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