A final rejuvenation phase creates a burst of new stars in massive galaxies
Massive galaxies do not go quietly into the night, it seems, as a new study has found they undergo a last gasp of star formation before shutting down completely.
What causes galaxies to stop birthing new stars has long been an astronomical conundrum. To find the answer, astronomers looked at 3,000 nearby galaxies which host active galactic nuclei (AGN) – galactic cores where the matter swirling around a black hole emits huge amounts of radiation. Rather than the slowly declining rates of star formation they expected, the team instead found formation rates were rising, suggesting AGNs are a rejuvenation phase –a last burst of star birth – before shutting down.
“Galaxies may undergo several rejuvenation episodes until they finally become dormant,” says Ignacio Martìn-Navarro from the Institute of Astrophysics of the Canary Islands, who led the study. www.iac.es/en