Supermassive Black Hole Winds Turn Up The Heat, Stopping Star Formation

Stars form when gases cool and collapse, but supermassive black holes release winds that heat up the gases in their host galaxy, preventing this from happening.

AsianScientist (Jun. 3, 2016) – Scientists in Japan have uncovered a new class of galaxies with supermassive black hole winds that are energetic enough to suppress future star formation. The findings were published in Nature.

Devoid of fresh young stars, red and dead galaxies make up a large fraction of galaxies in our nearby universe. A mystery that has plagued astronomers for years has been how these systems remain inactive, despite having all of the ingredients needed to form stars.

Now, researchers at the Kavli Institute for the Physics and Mathematics of the Universe in Kashiwa, Japan have succeeded at catching a supermassive black hole in the act of heating gas within its host galaxy—preventing star formation.

“Stars are created by the cooling and collapse of gas, but in these galaxies there are no new stars despite an abundance of gas. It’s like we have rain clouds hanging over a desert, but none of the rainwater is reaching the ground,” said lead author Dr. Edmond Cheung, a project researcher at the Institute.

The team studied a galaxy, nicknamed Akira, a prototypical example of the newly discovered class of galaxies called ‘red geysers.’ Red refers to the color of galaxies that lack young blue stars, and geyser refers to the episodic wind outbursts from the supermassive black hole.

Akira showed intriguing and complex patterns of warm gas, implying the presence of an outflowing wind from the supermassive black hole in its center. The researchers say the fuel for Akira’s supermassive black hole likely came from interactions with a smaller galaxy, nicknamed Tetsuo. The outflowing wind had enough energy to heat the surrounding gas through shocks and turbulence, and could ultimately prevent any future star formation.

These are some of the early results from the Kavli IPMU-led SDSS-IV MaNGA survey, which began observations in 2014. The technology involved in the new survey allows scientists to map galaxies ten to one hundred times faster than before, making it possible to build large enough samples required to catch galaxies undergoing rapidly changing phenomena.

“The critical power of MaNGA is the ability to observe thousands of galaxies in three dimensions, by mapping not only how they appear on the sky, but also how their stars and gas move inside them,” said co-lead author, Project Assistant Professor Kevin Bundy.

The team will continue to analyze the survey’s data and carry out follow-up studies to further reveal the role of red geysers in the evolution of galaxies.

The article can be found at: Cheung et al. (2016) Suppressing Star formation in Quiescent Galaxies with Supermassive Black Hole Winds.


Source: Kavli IPMU.
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