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Galaxies’ “Heart and Lungs” Prevent Premature Ageing
Context:
- Astrophysicists at the University of Kent, in a study published in Monthly Notices of the Royal Astronomical Society, suggest that galaxies use an internal “heart and lungs” system to avoid premature ageing.
- The study uses a biological analogy, comparing a galaxy’s central supermassive black hole to a “heart” and the bi-polar supersonic jets it emits to “lungs.”
The Mystery of Galaxy Size and Analogy:
- Astronomers have long wondered why galaxies aren’t as massive as they theoretically could be. Something seems to limit their growth, preventing them from becoming colossal behemoths.
- The Supermassive Black Hole (Galactic Heart): At the centre of most galaxies is a supermassive black hole, which can be thought of as the galaxy’s “heart.”
- This black hole emits powerful jets of gas and radiation, akin to our lungs’ airways.
- The Supersonic Jets (Galactic Lungs): These jets oscillate back and forth along both axes, much like our diaphragm moves to inflate and deflate our lungs.
- As the jets expand and contract, they transmit energy into the surrounding medium.
- Breathing Out Warm Air: Just as we exhale warm air, the jets release energy into space. This process slows down the galaxy’s accretion of gas, limiting its growth.
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Simulation Details:
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Implications:
- Without this internal regulation, the universe would have aged faster, and we would only see massive “zombie” galaxies filled with dead and dying stars.
- The rate of pulsation, size of the black hole, and effectiveness of the jets are critical to the balance of this “breathing” process.
- It provides a mechanism to explain the previously unexplained regulation of gas flow into galaxies, which influences their growth and longevity.