Quasar - RX J1131-1231 (Labeled)
Multiple images of a distant quasar are visible in this combined view from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The Chandra data, along with data from ESA's XMM-Newton, were used to directly measure the spin of the supermassive black hole powering this quasar. This is the most distant black hole where such a measurement has been made, as reported in our press release.
Gravitational lensing
by an intervening elliptical galaxy has created four different images
of the quasar, shown by the Chandra data in pink. Such lensing, first
predicted by Einstein,
offers a rare opportunity to study regions close to the black hole in
distant quasars, by acting as a natural telescope and magnifying the
light from these sources. The Hubble data in red, green and blue shows
the elliptical galaxy in the middle of the image, along with other
galaxies in the field.
The quasar is known as RX J1131-1231 (RX J1131 for short), located about 6 billion light years
from Earth. Using the gravitational lens, a high quality X-ray spectrum
- that is, the amount of X-rays seen at different energies - of RX
J1131 was obtained.
The X-rays are produced when a swirling accretion disk
of gas and dust that surrounds the black hole creates a
multimillion-degree cloud, or corona near the black hole. X-rays from
this corona reflect off the inner edge of the accretion disk. The
reflected X-ray spectrum is altered by the strong gravitational forces
near the black hole. The larger the change in the spectrum, the closer
the inner edge of the disk must be to the black hole.
The authors of the new study found that the X-rays are coming from a
region in the disk located only about three times the radius of the
event horizon, the point of no return for infalling matter. This implies
that the black hole must be spinning extremely rapidly to allow a disk
to survive at such a small radius.
This result is important because black holes are defined by just two
simple characteristics: mass and spin. While astronomers have long been
able to measure black hole masses very effectively, determining their spins have been much more difficult.
These spin measurements can give researchers important clues about
how black holes grow over time. If black holes grow mainly from
collisions and mergers between galaxies
they should accumulate material in a stable disk, and the steady supply
of new material from the disk should lead to rapidly spinning black
holes. In contrast if black holes grow through many small accretion
episodes, they will accumulate material from random directions. Like a
merry go round that is pushed both backwards and forwards, this would
make the black hole spin more slowly.
The discovery that the black hole in RX J1131 is spinning at over
half the speed of light suggests that this black hole has grown via
mergers, rather than pulling material in from different directions.
These results were published online in the journal Nature. The lead
author is Rubens Reis of the University of Michigan. His co-authors are
Mark Reynolds and Jon M. Miller, also of Michigan, as well as Dominic
Walton of the California Institute of Technology.
Scale: Image is 1.2 arcmin on a side (About 1.6 million light years)
Category: Quasars & Active Galaxies, Black Holes
Coordinates (J2000): RA 11h 31m 51.60s | Dec -12° 31' 57.00"
Constellation: Crater
Observation Date: 28 Nov 2009
Observation Time: 7 hours 39 min
Obs. ID: 11540
Instrument: ACIS
References: Reis, R.C., et al, 2014 Nature, in press.
Color Code: X-ray (Pink); Optical (Red, Green, Blue) Optical:
Distance Estimate: 6.05 billion light years (z=0.658)
Source: NASA’s Chandra X-ray Observatory
