The NASA visualization team created an overlay of an image of the Milky Way, taken by the European Space Agency’s Style space observatory, and a simulated visualization of the eRosita and Fermi bubbles prepared by Karen Yang (lead author of the study and co-professor at National Tsing Hua University in Taiwan) in collaboration. with Paper co-authors Mateusz Roskowski (University of Michigan) and Elaine Zwiebel (University of Wisconsin). Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO
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In 2020, the eRosita X-ray telescope captured images of two large bubbles stretching far above and below the center of our galaxy.
Since then, astronomers have debated their origins. Now, a study that includes research from the University of Michigan suggests that the bubbles are the result of an intense outpouring of activity from the supermassive black hole at the center of the Milky Way. Studies published in natural astronomyalso show that the jets began releasing matter about 2.6 million years ago, and lasted about 100,000 years.
The team’s findings suggest that the Fermi bubble, discovered in 2010, and the microwave haze — a cloud of charged particles roughly at the center of galaxies — formed from the same energy flow from a supermassive black hole. The study was led by National Tsing Hua University in collaboration with UM and the University of Wisconsin.
“Our findings are important in the sense that we need to understand how black holes interact with the galaxies within them, because these interactions allow these black holes to grow in a controlled way rather than in a controlled manner. [growing] “It’s out of control,” said UM astronomer Mateusz Roskowski, a co-author of the study. “If you believe in this Fermi OE Rosetta bubble model as the driving force supermassive black holeYou can start answering these deep questions.”
There are two competing models explaining this bubble, called the Fermi bubble and the eRosita after the telescope named after Ruszkowski. The first suggests that the outflow is driven by a nuclear stellar explosion, in which a star explodes in a supernova and ejects material. The second model, supported by the team’s findings, suggests that these outflows are driven by energy from the supermassive black hole at the center of our galaxy.
These outflows from a black hole occur as material moves toward the black hole, but they never cross the black hole’s event horizon, or the mathematical surface beneath which nothing can escape. Because some of this material is returned to space, black hole It doesn’t grow uncontrollably. But the energy released by the black hole moves material near the black hole, producing these huge bubbles.
The structure itself is 11 kiloparsecs high. One parsec is 3.26 light years, or about three times the distance light travels in a year. The structure, then, is about 36,000 light-years across.
For comparison, the Milky Way is 30 kilofresques in diameter, and our solar system is located about 8 kilofresques from the galactic center. The eRosita bubble is twice as large as the Fermi bubble and is expanded by the energy wave, or shock wave, propelled by the Fermi bubble, according to the researchers.
Astronomers are interested in paying attention to eRosita bubbles in particular because they occur in the backyard of our own galaxy rather than objects in different galaxies or at extreme cosmic distances. Our proximity to the outflow means astronomers can collect a large amount of data, Roskowski said. This data can tell astronomers how much energy is in the black hole’s field, how long this energy is injected, and what material the bubbles are made of.
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“Not only were we able to override the stellar explosion model, but we were also able to adjust the parameters needed to produce an image that is the same, or something very similar to what is in the sky, in the supermassive black hole model,” Roskowski said. “We can better limit certain things, like how much energy is pumped in, what’s inside the bubbles, and how long the energy is injected to produce these bubbles.”
What’s in it? Cosmic rays, a form of high energy radiation. eRosita Bubbles contains Fermi bubbles, contents unknown. But the researchers’ model could predict the number of cosmic rays inside each structure. The injection of energy from the black hole inflates the bubble, and the energy itself is in the form of kinetic energy, thermal energy, and cosmic rays. From this form of energy, the Fermi mission can only detect gamma-ray signals from cosmic rays.
Karen Yang, lead author of the study and assistant professor at National Tsing Hua University in Taiwan, began work on an early version of the code used for modeling in this paper as a postdoctoral researcher at MM University with Roskowski. To reach their conclusion, the researchers performed numerical simulations of the energy release that accounted for hydrodynamics, gravity and cosmic rays.
“Our simulation is unique in that it takes into account the interactions between cosmic rays and gas within the Milky Way. cosmic raysby injecting a black hole jet, it expands and forms a Fermi bubble that glows in gamma rays,” said Yang.
“The explosion itself pushed the gas away from the galactic center and formed a shock wave that was observed as an eRosita bubble. New observations of the eRosita bubble have allowed us to more precisely limit the duration of black hole activity, and to better understand the past. the history of our galaxy.”
The researchers’ model ruled out the nuclear stellar explosion theory because the typical duration of a nuclear stellar explosion, and thus the length of time a stellar explosion would have pumped out the energy that formed the bubble, was about 10 million years, according to the study’s colleagues. Author. Elaine Zwiebel, professor of astronomy and physics at the University of Wisconsin.
“On the other hand, our active black hole model accurately predicts the relative size of the eRosita X-ray bubble and the Fermi gamma-ray bubble, provided the energy injection time is about 1% of that, or one tenth of a million years,” Zwebel said.
“Injecting energy over 10 million years would produce a bubble with a completely different appearance. This is an opportunity to compare X-ray and gamma-ray bubbles that provide an important part that was missing before.”
The researchers used data from the eRosita mission, NASA’s Fermi Gamma-Ray Space Telescope, the Planck Observatory and the Wilkinson Microwave Anisotropy Probe.
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H.-Y. Karen Yang et al., Fermi bubble and eROSITA as traces of galactic center black hole activity in the past, natural astronomy (2022). DOI: 10.1038 / s41550-022-01618-x–
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University of Michigan
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quote: Massive bubble in the center of the Milky Way caused by a supermassive black hole (2022, 8 March) retrieved on March 8, 2022 from https://phys.org/news/2022-03-massive-center-milky-supermassive-black.html
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