Inside the galaxy cluster Abell 3667 lies a bridge-like structure spanning millions of light-years, built from stars.
“This is the first time a feature of this scale and size has been found in a local galaxy cluster (i.e., clusters near us),” lead researcher Anthony Englert from Brown University in Rhode Island (USA) told Live Science.
Discovery of a Massive “Light Bridge” Connecting Two Galaxies
The spectacular light bridge inside galaxy cluster Abell 3667 – Image: CTIO/NOIRLab/NSF/AURA
Published in The Astrophysical Journal, the research team stated that the luminous “bridge” inside Abell 3667 is a thin stellar stream connecting the two brightest galaxies in the cluster.
However, this fairytale-like structure is actually the result of a violent cosmic event: two galaxy clusters attempting to devour each other.
Analyses reveal that Abell 3667 is the product of two smaller galaxy clusters that began merging around a billion years ago, each with its own dominant central galaxy.
The light bridge—where stars are being pulled from one galaxy to another—shows that the two “kings” of the former clusters are still in the process of merging. Their satellite galaxies are following suit.
Thus, this extraordinary stellar bridge promises rare insights into the history of Abell 3667.
Researchers detected this faint bridge by stacking 28 hours of observations conducted over several years using the Dark Energy Camera at the Cerro Tololo Inter-American Observatory in Chile.
The light from this bridge is intracluster light (ICL), a diffuse glow from stars stripped from their home galaxies due to intense gravitational forces.
As a result, the light bridge also provides valuable data for probing dark matter, the invisible substance believed to make up about 80% of the universe’s mass.
Astronomers explain that intracluster light tends to follow the same path as dark matter, offering an indirect way to map its distribution.