Ring Around the Cluster
Explanation:
It is difficult to hide a galaxy behind a cluster of galaxies.
The closer cluster's gravity will act like a
huge lens,
pulling images of the distant galaxy
around the sides and greatly distorting them.
This is just the case observed in the above
recently released image from the
VLT.
The cluster CL2244-02 is composed of
many yellow galaxies and is
lensing the image of a
blue-white background galaxy into a huge arc.
Careful inspection of the image will reveal
at least one other
lensed background galaxy appearing in red.
The foreground
cluster
can only create such a smooth arc if
most of its mass is smoothly distributed
dark matter - and therefore not
concentrated in the yellow galaxies visible.
Analyzing these
gravitational arcs
gives astronomers a method to estimate the
dark matter distribution in
clusters of galaxies.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
