Black Hole Jets Hotter Than Expected
New measurements show that quasars can blow far past the theoretical temperature limit of 100 billion degrees Kelvin (179 billion degrees Fahrenheit), which has scientists puzzled.
New observations of a jet-emitting black hole show astonishing temperatures inside the jets of 10 trillion degrees Kelvin - a toasty 18 trillion degrees Fahrenheit. This new measurement shows that quasars can blow far past the theoretical temperature limit of 100 billion degrees Kelvin (179 billion degrees Fahrenheit), which has scientists puzzled.
"This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate," said lead author Yuri Kovalev of the Moscow's Lebedev Physical Institute in a statement.
Observations of quasar 3C 273 were done with the Russian Skeptr-R satellite working in concert with three ground observatories as part of the larger RadioAstron mission. Quasars are supermassive black holes that emit intense jets of radiation.
Previously, it was believed there was a limit to the temperature because the electrons inside the jet would produce X-rays and gamma rays, interact with each other and cool down.
Astronomers hailed the finding as a triumph for interferometry, which occurs when multiple telescopes are linked together to get fine resolution of a distant object. The four observatories working together can get better resolution than the Hubble Space Telescope (although Hubble does not observe in X-rays or gamma rays).
The team also had a secondary find, which was that 3C 273 had previously unknown visible distortions to its substructure as seen from Earth, caused by peering through the interstellar medium in our own Milky Way. The distortion was only spotted because of the resolution of RadioAstron, researchers said in a statement.
The results were published in The Astrophysical Journal.
Artist's impression of a quasar, with a supermassive black hole in the center.
Artist's impression of a spinning supermassive black hole with a surrounding accretion disk and relativistic jets.
How to measure the spin of a black hole: This chart illustrates the basic model for determining the spin rates of black holes. The three artist's concepts represent the different types of spin: retrograde rotation, where the disk of matter falling onto the hole, called an accretion disk, moves in the opposite direction of the black hole; no spin; and prograde rotation, where the disk spins in the same direction as the black hole.
Two models of black hole spin: Scientists measure the spin rates of supermassive black holes by spreading the X-ray light into different colors. The light comes from accretion disks that swirl around black holes, as shown in both of the artist's concepts. They use X-ray space telescopes to study these colors, and, in particular, look for a "fingerprint" of iron -- the peak shown in both graphs, or spectra -- to see how sharp it is. Prior to observations with NASA's Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency's XMM- Newton telescope, there were two competing models to explain why this peak might not appear to be sharp. The "rotation" model shown at top held that the iron feature was being spread out by distorting effects caused by the immense gravity of the black hole. If this model were correct, then the amount of distortion seen in the iron feature should reveal the spin rate of the black hole. The alternate model held that obscuring clouds lying near the black hole were making the iron line appear artificially distorted. If this model were correct, the data could not be used to measure black hole spin.
This chart depicts the electromagnetic spectrum, highlighting the X-ray portion. NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's XMM-Newton telescope complement each other by seeing different colors of X-ray light. XMM-Newton sees X-rays with energies between 0.1 and 10 kiloelectron volts (keV), the "red" part of the spectrum, while NuSTAR sees the highest-energy, or "bluest," X- ray light, with energies between 3 and 70 keV.
This image taken by the ultraviolet-light monitoring camera on the European Space Agency's (ESA's) XMM-Newton telescope shows the beautiful spiral arms of the galaxy NGC1365. Copious high-energy X-ray emission is emitted by the host galaxy, and by many background sources. The large regions observed by previous satellites contain so much of this background emission that the radiation from the central black hole is mixed and diluted into it. NuSTAR, NASA's newest X-ray observatory, is able to isolate the emission from the black hole, allowing a far more precise analysis of its properties.
What XMM-Newton saw: The solid lines show two theoretical models that explain the low-energy X-ray emission seen from the galaxy NGC 1365 by the European Space Agency's XMM-Newton. The red line explains the emission using a model where clouds of dust and gas partially block the X-ray light, and the green line represents a model in which the emission is reflected off the inner edge of the accretion disk, very close to the black hole. The blue circles show the measurements from XMM-Newton, which are explained equally well by both models.
Two X-ray observatories are better than one: NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, has helped to show, for the first time, that the spin rates of black holes can be measured conclusively. It did this, together with the European Space Agency's XMM-Newton, by ruling out the possibility that obscuring clouds were partially blocking X-ray right coming from black holes. The solid lines show two theoretical models that explain low-energy X-ray emission seen previously from the spiral galaxy NGC 1365 by XMM-Newton. The red line explains the emission using a model where clouds of dust and gas partially block the X-ray light, and the green line represents a model in which the emission is reflected off the inner edge of the accretion disk, very close to the black hole. The blue circles show the latest measurements from XMM-Newton, and the yellow circles show the data from NuSTAR. While both models fit the XMM-Newton data equally well, only the disk reflection model fits the NuSTAR data.