A study has found that galaxies have a regulatory mechanism similar to a heart and lungs, which controls their growth by limiting gas absorption. This mechanism, involving a supermassive black hole and its jet emissions, prevents galaxies from expanding too rapidly, ensuring their longevity and preventing premature aging into “zombie” galaxies.
Galaxies avoid an early death because they have a “heart and lungs” that regulate their “breathing” and prevent them from growing out of control. A new study published in the Monthly Notices of the Royal Astronomical Society investigates why galaxies are not as large as astronomers would expect, with something limiting gas absorption to convert into stars.
Astrophysicists at the University of Kent suggest that galaxies could control their growth rate through their “breathing.” They compared the supermassive black hole at a galaxy’s center to its heart and the jet emissions to airways feeding a pair of lungs. Pulses from the black hole can lead to jet shock fronts oscillating back and forth, like the thoracic diaphragm in the human body, resulting in slowing gas accretion and growth.
PhD student Carl Richards developed the theory after creating new simulations to investigate the role supersonic jets might play in inhibiting galaxy growth. The simulations involved allowing the black hole “heart” to pulse and the jets to be at high pressure, causing the jets to “act like bellows” by sending out sound waves like ripples on a pond surface.
The researchers found that the overpressured jets effectively expanded “like air-filled lungs,” transmitting sound waves into the surrounding galaxy in the form of a series of pressure ripples, which suppressed galaxy growth. The study concludes that a galaxy’s lifespan can be extended with the help of its “heart and lungs,” where the supermassive black hole engine at its core helps inhibit growth by limiting gas absorption.
Reference: “Simulations of pulsed overpressure jets: formation of bellows and ripples in galactic environments” by Carl Richards and Michael D Smith, 12 July 2024, Monthly Notices of the Royal Astronomical Society.
Source: https://scitechdaily.com/black-holes-not-destroyers-but-protectors/