Record-breaking ultraviolet winds discovered near black hole
The fastest winds ever seen at ultraviolet wavelengths have been discovered near a supermassive black hole by a research team that includes a Penn State University astronomer. "This new ultrafast wind surprised us when it appeared at ultraviolet wavelengths, indicating it is racing away from the ravenous black hole at unprecedented speeds -- almost like a bat out of Hell," said William Nielsen (Niel) Brandt, the Verne M. Willaman Professor of Astronomy and Astrophysics and a professor of physics at Penn State, a member of the research team.
"We're talking wind speeds of more than 200 million miles an hour, equivalent to a category 77 hurricane," said Jesse Rogerson, who led the research as part of his efforts toward earning a Ph.D. degree in the Department of Physics and Astronomy at York University in Canada.
The ultraviolet-wavelength winds are coming from the black hole's quasar -- the disk of hot gas that surrounds the black hole. Quasars form around supermassive black holes at the centers of massive galaxies. Quasars are bigger than Earth's orbit around the Sun and hotter than the surface of the Sun, generating enough light to be seen across the observable universe. "An exciting discovery in recent years has been the realization that ultraviolet winds from quasars can both appear and disappear when viewed from Earth, depending on various conditions surrounding the black hole," Brandt said.
The team's discovery of the fastest ultraviolet wind ever confirmed from a quasar will be published in the March 21, 2016, print issue of the Monthly Notices of the Royal Astronomical Society.
"Black holes can have a mass that is billions of times larger than the Sun, mostly because they are messy eaters in a way, capturing any material that ventures too close," said York University Associate Professor Patrick Hall, who is Rogerson's supervisor. "But as matter spirals toward a black hole, some of it is blown away by the heat and light of the quasar. These are the winds that we are detecting."
The research team used data from a large survey of the sky known as the Sloan Digital Sky Survey (SDSS) to identify new outflows from quasars. After spotting about 300 examples, the astronomers selected about 100 for further exploration, collecting data with the Gemini Observatory's twin telescopes in Hawaii and Chile.
Much of this research is aimed at better understanding outflows from quasars and why they happen. "Quasar winds play an important role in galaxy formation," said Rogerson. "When galaxies form, these winds fling material outwards and deter the creation of stars. If such winds didn't exist or were less powerful, we would see far more stars in big galaxies than we actually do. Hubble Space Telescope images of galaxies would look much different if quasar winds did not exist."
In addition to Brandt, Rogerson, and Hall, other members of the research team are Paola Rodríguez Hidalgo of York University and Humboldt State University; Patrik Pirkola of York University; and Nurten Filik Ak, a former Penn State graduate student who now is a professor of astrophysics at Erciyes University in Turkey. This research was supported, in part, by grants from the Natural Sciences and Engineering Research Council of Canada, the National Science Foundation of the United States, and the Scientific and Technological Research Council of Turkey.
[ Barbara K. Kennedy / Margaret Mroziewicz ]