Artist's impression of black-hole wind in a galaxy and XMM-Newton and NuSTAR spectrum of the quasar PDS 456

Artist's impression of black-hole wind in a galaxy

XMM-Newton and NuSTAR

Copyright: NASA/JPL-Caltech; Insert: ESA 

This illustration shows the powerful wind driven by the supermassive black hole at the centre of a galaxy. The schematic figure in the insert depicts the innermost regions of the galaxy where a black hole accretes the surrounding matter (light grey) at a very high pace via a disc (darker grey). At the same time, part of that matter is cast away through powerful winds.

A study based on joint observations with ESA's XMM-Newton and NASA's NuSTAR X-ray telescopes of the quasar PDS 456, which hosts a very active black hole, has shown that the winds driven by a black hole can be wide and almost spherical. This discovery supports the picture of black holes having a significant impact on star formation of their host galaxy.

The artwork of the galaxy is based on an image of the Pinwheel galaxy (Messier 101) taken by the NASA/ESA Hubble Space Telescope.

XMM-Newton and NuSTAR spectrum of the quasar PDS 45

Copyright: NASA/JPL-Caltech/Keele Univ.
Source: ESA/XMM-Newton 

This plot of data from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. The winds blow in every direction, in a nearly spherical fashion, coming from both sides of a galaxy (only one side is shown in the artist's impression here). 

The plot shows the brightness of X-ray light from an extremely luminous quasar called PDS 456, with the highest-energy rays on the right. XMM-Newton sees lower-energy X-rays, and NuSTAR, higher. XMM Newton had previously observed PDS 456 in 2001. At that time, it had measured the X-rays up to an energy level of 11 kiloelectron volts. From those data, researchers detected a dip in the X-ray light, called an absorption feature (see dip in plot). The dip is caused by iron atoms – which are carried by the winds along with other matter – absorbing the X-ray light of a particular energy. What's more, the absorption feature is 'blue-shifted," meaning that the winds are speeding toward us.

These data told researchers that at least some of the winds were blowing toward us – but they didn't reveal whether those winds were confined to a narrow beam along our line of sight, or were blowing in all directions. That's because XMM-Newton had only detected absorption features, which by definition occur in front of a light source, in this case, the quasar. To probe what was happening at the other sides of the quasar, the astronomers needed to find an emission feature, which would indicate that the iron was scattering X-ray light at a particular energy in all directions, not only toward the observer.

NuSTAR and XMM-Newton teamed up to observe PDS 456 simultaneously in 2013 and 2014, and the results of that campaign are shown in this plot. NuSTAR data are represented as orange circles and XMM-Newton as blue squares. The NuSTAR data reveal the baseline of the "continuum" quasar light (see gray line) – or what the quasar would look like without any winds. What stands out is the bump to the left of the dips. That is an iron emission signature, the telltale sign that the black-hole winds blow to the sides and in all directions.

Source: ESA/XMM-Newton

NASA, ESA Telescopes Give Shape to Furious Black Hole Winds

Supermassive black holes at the cores of galaxies blast radiation and ultra-fast winds outward, as illustrated in this artist's conception. Image credit: NASA/JPL-Caltech.  › Full image and caption

This plot of data from two space telescopes, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. Image credit: NASA/JPL-Caltech/Keele Univ.  › Full image and caption

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and ESA's (European Space Agency) XMM-Newton telescope are showing that fierce winds from a supermassive black hole blow outward in all directions -- a phenomenon that had been suspected, but difficult to prove until now.

This discovery has given astronomers their first opportunity to measure the strength of these ultra-fast winds and prove they are powerful enough to inhibit the host galaxy's ability to make new stars.

"We know black holes in the centers of galaxies can feed on matter, and this process can produce winds. This is thought to regulate the growth of the galaxies," said Fiona Harrison of the California Institute of Technology (Caltech) in Pasadena, California. Harrison is the principal investigator of NuSTAR and a co-author on a new paper about these results appearing in the journal Science. "Knowing the speed, shape and size of the winds, we can now figure out how powerful they are."

Supermassive black holes blast matter into their host galaxies, with X-ray-emitting winds traveling at up to one-third the speed of light. In the new study, astronomers determined PDS 456, an extremely bright black hole known as a quasar more than 2 billion light-years away, sustains winds that carry more energy every second than is emitted by more than a trillion suns.

"Now we know quasar winds significantly contribute to mass loss in a galaxy, driving out its supply of gas, which is fuel for star formation," said the study's lead author, Emanuele Nardini of Keele University in England.

NuSTAR and XMM-Newton simultaneously observed PDS 456 on five separate occasions in 2013 and 2014. The space telescopes complement each other by observing different parts of the X-ray light spectrum: XMM-Newton views low-energy and NuSTAR views high-energy.

Previous XMM-Newton observations had identified black-hole winds blowing toward us, but could not determine whether the winds also blew in all directions. XMM-Newton had detected iron atoms, which are carried by the winds along with other matter, only directly in front of the black hole, where they block X-rays. The scientists combined higher-energy X-ray data from NuSTAR with observations from XMM-Newton. By doing this, they were able to find signatures of iron scattered from the sides, proving the winds emanate from the black hole not in a beam, but in a nearly spherical fashion.

"This is a great example of the synergy between XMM-Newton and NuSTAR," said Norbert Schartel, XMM-Newton project scientist at ESA. "The complementarity of these two X-ray observatories is enabling us to unveil previously hidden details about the powerful side of the universe."

With the shape and extent of the winds known, the researchers could then determine the strength of the winds and the degree to which they can inhibit the formation of new stars.

Astronomers think supermassive black holes and their home galaxies evolve together and regulate each other's growth. Evidence for this comes in part from observations of the central bulges of galaxies -- the more massive the central bulge, the larger the supermassive black hole.

This latest report demonstrates a supermassive black hole and its high-speed winds greatly affect the host galaxy. As the black hole bulks up in size, its winds push vast amounts of matter outward through the galaxy, which ultimately stops new stars from forming.

Because PDS 456 is relatively close, by cosmic standards, it is bright and can be studied in detail. This black hole gives astronomers a unique look into a distant era of our universe, around 10 billion years ago, when supermassive black holes and their raging winds were more common and possibly shaped galaxies as we see them today.

"For an astronomer, studying PDS 456 is like a paleontologist being given a living dinosaur to study," said study co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena. "We are able to investigate the physics of these important systems with a level of detail not possible for those found at more typical distances, during the 'Age of Quasars.'"

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.

For more information, visit: http://www.nasa.gov/nustar  -  http://www.nustar.caltech.edu/

Media Contact

Whitney Clavin
Jet Propulsion Laboratory, Pasadena, California
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Felicia Chou
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202-358-0257
felicia.chou@nasa.gov

Source: JPL-Caltech/News