Supernova explosions and the jets of a monstrous black hole are scattering a galaxy's star-making gas like a cosmic leaf blower, a new study finds. The findings, which relied on ultraviolet observations from NASA's Galaxy Evolution Explorer and a host of other instruments, fill an important gap in the current understanding of galactic evolution.It has long been known that gas-rich spiral galaxies like our Milky Way smash together to create elliptical galaxies such as the one observed in the study. These big, round galaxy have very little star formation. The reddish glow of aging stars comes to dominate the complexion of elliptical galaxies, so astronomers refer to them as "red and dead."
The process that drives the dramatic transformation from spiral galactic youth to elderly elliptical is the rapid loss of cool gas, the fuel from which new stars form. Supernova explosions can start the decline in star formation, and then shock waves from the supermassive black hole finish the job. Now astronomers think they have identified a recently merged galaxy where this gas loss has just gotten underway.
"We have caught a galaxy in the act of destroying its gaseous fuel for new stars and marching toward being a red-and-dead type of galaxy," said Ananda Hota, lead author of a new paper in the Monthly Notices of the Royal Astronomical Society. Hota, an astronomer in Pune, India, conducted the study as a post-doctoral research fellow at the Institute of Astronomy & Astrophysics at Academia Sinica in Taipei, Taiwan.
"We have found a crucial missing piece to connect and solve the puzzle of this phase of galaxy evolution," Hota added.
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