A new study has provided deeper insight into how big black holes can block formation of new stars in the aging galaxies. The study found that massive black holes spewing out radio-frequency-emitting particles at near-light speed can block new stars.
The research provided crucial new evidence that it was these jets of "radio-frequency feedback" streaming from mature galaxies' central black holes that prevent hot free gas from cooling and collapsing into baby stars.
Johns Hopkins postdoctoral fellow Megan Gralla found that the Sunyaev–Zel'dovich effect signature , typically used to study large galaxy clusters could also be used to learn a great deal about smaller formations. The SZ effect occurs when high-energy electrons in hot gas interact with faint light in the cosmic microwave background, light left over from earliest times when the universe was a thousand times hotter and a billion times denser than today.
In space, hot gas drawn into a galaxy can cool and condense, forming stars. Some gas also funnels down into the galaxy's black hole, which grows together with the stellar population. This cycle can repeat continuously; more gas would be pulled in to cool and condense, more stars begin to shine and the central black hole grows more massive. However, in nearly all mature galaxies, the big galaxies called "elliptical" because of their shape that gas doesn't cool any more, which ultimately means no stars.
Tobias Marriage, Gralla and their collaborators found that the elliptical galaxies with radio-frequency feedback – relativistic radio-frequency-emitting particles shooting from the massive central black holes at their center at close to the speed of light, all contain hot gas and a dearth of infant stars. That provides crucial evidence for their hypothesis that this radio-frequency feedback was the "off switch" for star-making in mature galaxies.
The study is published in the journal Monthly Notices of the Royal Astronomical Society.
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