Proto supermassive binary black hole detected in X-rays (Forwarded)

Journal Astronomy & Astrophysics
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Contact persons:

Science:

Dr. Daniel Hudson
Phone: +49 228 73 6788

Dr. Thomas Reiprich
Phone: +49 228 73 3642

Dr. Craig L. Sarazin
Phone: +1 434 924 4903

Dr. Tracy E. Clarke
Email: tracy.clarke (at) nrl.navy.mil

Press office:

Dr. Jennifer Martin
Journal Astronomy & Astrophysics
Phone: +33 1 43 29 05 41

Press Release: April 6th, 2006

This press release is issued as a collaboration with the University of
Bonn, the University of Virginia, the U.S. Naval Research Laboratory, the
Chandra X-ray Observatory Center , and Astronomy & Astrophysics.

Proto supermassive binary black hole detected in X-rays

An international team of astronomers led by D. Hudson from the University
of Bonn has detected a proto supermassive binary black hole in images of
NASA's Chandra X-ray observatory. They found that these two black holes
are gravitationally bound and orbit each other. Their results will be
published in an upcoming issue of Astronomy & Astrophysics.

An international team of astrophysicists, led by D. Hudson from the
University of Bonn and including the U.S. Naval Research Laboratory and
the University of Virginia, presents their X-ray detection of a proto
supermassive binary black hole. Their results will be published in an
upcoming issue of Astronomy & Astrophysics. The image of this proto binary
black hole was obtained with NASA's Chandra X-ray Observatory. The two
black holes have already been seen in radio images. The new X-ray images
provide unique evidence that these two black holes are in the process of
forming a binary system; that is, they are gravitationally bound and orbit
each other.

The two black holes are located in the nearby galaxy cluster Abell 400.
With high-resolution Chandra data, the team was able to spatially resolve
the two supermassive black holes (separated by 15") at the centre of the
cluster. Each black hole is located at the centre of its respective host
galaxy and the host galaxies appear to be merging. It is not, however,
just the two host galaxies that are colliding -- the whole cluster in
which they live is merging into another neighbouring galaxy cluster.

Using these new data, the team show that the two black holes are moving
through the intracluster medium at the supersonic speed of about 1200
km/s. The wind from such a motion would cause the radio plasma emitted
from these two black holes to bend backwards. Although this bending had
been observed previously, the cause of it was still being debated. Since
the bending of the jets due to this motion is in the same direction, it
suggests that the two black holes are travelling along the same path
within the cluster and are therefore gravitationally bound.

These two black holes became gravitationally bound when their host
galaxies collided. In several million years, the two black holes will
probably coalesce causing a burst of gravitational waves, as predicted by
Einstein's theory of relativity. This event will produce one of the
brightest sources of gravitational radiation in the Universe. Although we
will not be around to see this particular one, the observations provide
additional evidence that such bound systems exist and are currently
merging. The gravitational waves produced by these mergers are believed to
be the biggest source of gravitational waves to be detected by the future
Laser Interferometer Space Antenna (LISA).

The team includes D.S. Hudson (AIfA,Germany), T.H. Reiprich
(AIfA,Germany), T.E. Clarke (NRL & Interferometrics Inc.,USA), and C.L.
Sarazin (UVa,USA).

X-ray detection of the proto supermassive binary black hole at the centre
of Abell 400
by D.S Hudson, T.H. Reiprich, T.E. Clarke, and C.L. Sarazin.
To be published in Astronomy & Astrophysics (DOI number:
10.1051/0004-6361:20064955)

Full article available in PDF format,

http://www.edpsciences.org/articles/...PRAA200608.pdf

IMAGE CAPTION:
[http://www.edpsciences.org/papers/aa...608/pr_fig.gif
(76KB)]
This image shows the central region of the galaxy cluster Abell 400. The
colour coding gives the temperature of the X-ray emitting gas trapped in
the cluster: black-cold (18 million degrees Celsius) to white-hot (38
million degrees Celsius). The contours show the radio emission from the
jets of plasma being expelled by the black holes. As the two black holes
stream through the gas at supersonic velocities, the jets are bent toward
the top of the image. The gas in front of the black holes is compressed
and heated, as seen by the hotspot below them.

The inset shows a blow up of the central regions. Each dot represents a
position where an X-ray photon has struck Chandra's X-ray camera. The two
black holes are seen as bright regions where as many as 250 X-ray photons
struck the camera. The contours again show the radio emission from the
black holes and the jets of plasma being ejected from them.

[NOTE: Additional images are available at
http://chandra.harvard.edu/photo/2006/a400/ ]