Young galaxies are bright and colorful as they actively form new stars but as they age, they eventually stop producing stars becoming dark and lifeless.
Mystery Of Dimming Galaxies
The reason behind dimming galaxies has long baffled scientists. While these galaxies contain the necessary ingredients to form new stars, some fail to do it, a phenomenon that scientists compare with densely clouded regions having deserts instead of rain and vegetation.
A new study that paved way to the discovery of Akira, which belongs to a new class of galaxies known as Red Geysers, may provide some answer.
What Are Red Geysers?
Red geysers are old galaxies with low-energy supermassive black holes that drive intense interstellar winds. These winds heat up the galaxies' gas, which prevents cooling and condensation necessary to form new stars.
Astrophysicist Michele Cappellari, from Oxford University, explained that stars form from the galaxies' gas similar to how drops of rain condense from water vapor. The gas needs to cool down so condensation can occur.
What Keeps Galaxies From Making New Stars?
Scientists do not know what prevents cooling from occurring in many galaxies but by mapping the center and outer edges of hundreds of galaxies, Cappellari and colleagues found that supermassive black holes, which lie at the center of these galaxies, pull away cold gas allowing the gas to escape the galaxy's gravitational pull.
By using data from a Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to model the winds and gas movement in Akira, the researchers showed the driving mechanism of the wind likely originates from the near-dormant galaxy's nucleus.
This is the region where the energy powered by a supermassive black hole can produce wind with enough mechanical energy to heat cooler gas in the galaxy and suppress the formation of stars.
"In a prototypical example, we calculate that the energy input from the galaxy's low-level active supermassive black hole is capable of driving the observed wind, which contains sufficient mechanical energy to heat ambient, cooler gas (also detected) and thereby suppress star formation," Cappellari and colleagues wrote in their study.
The study was published in the journal Nature on May 25.