One of the problems of explaining the universe we live in is the presence of heavy elements. After all, the cosmos was a simple matter right after the Big Bang, with hydrogen and helium its only ingredients. Creating the heavier elements required stars, the model being that their eventual death in massive supernova explosions scattered ‘star stuff,’ as Carl Sagan liked to call it, throughout the universe, leading to the wide range of elements we see today and, of course, to life.
New research is adding black holes to that picture, seeing them as influential in spreading these same elements far and wide. The supermassive black hole at the center of the galaxy NGC 4051 is at the center of investigation. A research team led by Yair Krongold (Universidad Nacional Autónoma de México) has found that gas is escaping the black hole from a source closer to its Schwarzschild radius than previously thought. In the case of NGC 4051, that radius — the point beyond which nothing can escape the black hole — is about four million miles.
Although the accreting material in question is about 2000 times that distance, between 95 and 98 percent of it does go on to fall into the black hole. But that leaves between two and five percent that does not. The so-called ‘winds’ from black holes like this one pump heavier elements like carbon and oxygen back out of the galactic core, where they eventually become part of the clouds of dust and gas in which new stars form.
Thus we learn more about the influence of black holes on their surroundings, and their implied role in re-distributing the elements needed for life. But one puzzle remains: The fraction of escaping gas in the case of NGC 4051 is too low to account for the heavier elements found in intergalactic space. The team’s next goal, then, is to see whether more powerful active galaxies allow a greater percentage of nearby gases to escape. That work will continue using the same XMM-Newton space observatory techniques that produced the first result.
More on this in Krongold et al., “The Compact, Conical, Accretion-Disk Warm Absorber of the Seyfert 1 Galaxy NGC 4051 and its Implications for IGM-Galaxy Feedback Processes,” Astrophysical Journal 659 (April 20 2007), pp. 1022-1039 (abstract available)