2015

Keele astronomers have discovered that the winds from supermassive black holes at the centre of galaxies blow outward in all directions and can affect the star formation history of the host, a suspected phenomenon that had been difficult to prove before now.

 

These new findings, made possible by observations with ESA's XMM-Newton and NASA's NuSTAR X-ray telescopes, demonstrate that a supermassive black hole and the galaxy that nurtures it are connected on global scales by high-speed winds arising in the very central regions. As the black hole bulks up in size, its winds push vast amounts of matter outwards through the galaxy, which ultimately stops new stars from forming.

 

"We now know that quasar winds significantly contribute to mass loss in a galaxy, driving out its supply of gas, which is fuel for star formation," said Dr Emanuele Nardini, of the Keele X-ray Astrophysics Group and lead author of the study. "This study provides a unique view of the possible mechanism that links the evolution of the central black holes to that of their host galaxies over cosmic time."

 

With the shape and extent of the winds determined, the researchers could then figure out their power and answer general questions about the degree to which they can quench the formation of new stars. Astronomers think that supermassive black holes and their galaxies co-evolve together, regulating each other's growth.

 

"Black holes of this kind are very powerful, but their gravitational field only extends over the very inner parts of a galaxy," explains Dr Nardini. "For black holes to have substantial impact on the star-forming activity of an entire galaxy, there must be a feedback mechanism connecting the two on a global scale."

 

One possibility is that the propagation of winds driven by the black hole's accretion activity plays a role and, as published in the journal Science today, Dr Nardini and collaborators have obtained the first solid evidence supporting this scenario. This study gives astronomers a unique glimpse of a past era, around 10 billion years ago, when supermassive black holes and their fierce winds were much more common and possibly shaped the galaxies as we see them today.