More Images of Abell 520
X-ray, Optical & Lensing Images of Abell 520
Astronomers have discovered a chaotic scene unlike any witnessed before
in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra
X-ray Observatory and optical telescopes revealed a dark matter core
that was mostly devoid of galaxies, which may pose problems for current
theories of dark matter behavior.
(Credit: X-ray: NASA/CXC/UVic./A.Mahdavi et al.; Optical/Lensing: CFHT/UVic./A.Mahdavi et al.)
Illustration of Abell 520 System
An artist's illustration of the Abell 520 system shows where the bulk of
the matter (blue) is found compared to the individual galaxies (yellow) and
the hot gas (red) in the aftermath of a massive galaxy cluster collision.
The material shown in blue is dominated by dark matter. As with the Bullet
Cluster there are large separation between the regions where the galaxies
are most common (peaks 2 and 4) and where most of the hot gas lies (peak
3). However, unlike the Bullet Cluster, a concentration of dark matter is
found (peak 3) near the bulk of the hot gas, where very few galaxies are
located. In addition, there is an area (peak 5) where there are several
galaxies but very little dark matter. These observations conflict with the
general understanding that dark matter and the galaxies should remain
together, despite a violent collision. This raises questions about the
current understanding of how dark matter behaves.
Comparison of Abell 520 and Bullet Cluster
While there are certain similarities between Abell 520 and the so-called
, other significant differences raise interesting
scientific questions. For example, the dark matter and the galaxies in
the Bullet Cluster remained together despite the enormous collision
between the galaxy clusters. In the case of Abell 520, these components
have been separated, which flies in the face of conventional
understanding of dark matter.
Return to Abell 520 (16 Aug 07)
Abell 520 with Scale Bar